Showing papers in "Nanomaterials in 2017"
TL;DR: This review discusses various enhancement technologies such as the use of ultrasounds for in-process nanoparticles dispersion and of processing aspects to reach optimal properties for using nanocomposites in the selected applications.
Abstract: For the last decades, nanocomposites materials have been widely studied in the scientific literature as they provide substantial properties enhancements, even at low nanoparticles content. Their performance depends on a number of parameters but the nanoparticles dispersion and distribution state remains the key challenge in order to obtain the full nanocomposites’ potential in terms of, e.g., flame retardance, mechanical, barrier and thermal properties, etc., that would allow extending their use in the industry. While the amount of existing research and indeed review papers regarding the formulation of nanocomposites is already significant, after listing the most common applications, this review focuses more in-depth on the properties and materials of relevance in three target sectors: packaging, solar energy and automotive. In terms of advances in the processing of nanocomposites, this review discusses various enhancement technologies such as the use of ultrasounds for in-process nanoparticles dispersion. In the case of nanocoatings, it describes the different conventionally used processes as well as nanoparticles deposition by electro-hydrodynamic processing. All in all, this review gives the basics both in terms of composition and of processing aspects to reach optimal properties for using nanocomposites in the selected applications. As an outlook, up-to-date nanosafety issues are discussed.
514 citations
TL;DR: The presented review article summarizes the findings regarding the design and synthesis of magnetic materials focused on biomedical applications and highlights the utilization of magneticmaterials in separation/preconcentration of various molecules and cells, and their use in diagnosis and therapy.
Abstract: The increasing number of scientific publications focusing on magnetic materials indicates growing interest in the broader scientific community. Substantial progress was made in the synthesis of magnetic materials of desired size, morphology, chemical composition, and surface chemistry. Physical and chemical stability of magnetic materials is acquired by the coating. Moreover, surface layers of polymers, silica, biomolecules, etc. can be designed to obtain affinity to target molecules. The combination of the ability to respond to the external magnetic field and the rich possibilities of coatings makes magnetic materials universal tool for magnetic separations of small molecules, biomolecules and cells. In the biomedical field, magnetic particles and magnetic composites are utilized as the drug carriers, as contrast agents for magnetic resonance imaging (MRI), and in magnetic hyperthermia. However, the multifunctional magnetic particles enabling the diagnosis and therapy at the same time are emerging. The presented review article summarizes the findings regarding the design and synthesis of magnetic materials focused on biomedical applications. We highlight the utilization of magnetic materials in separation/preconcentration of various molecules and cells, and their use in diagnosis and therapy.
411 citations
TL;DR: A review of the most common metallic SERS substrates for chemical detection only is discussed, as well as SERS paradigms that are commercially available that have been addressed.
Abstract: The SERS effect was initially discovered in the 1970s. Early research focused on understanding the phenomenon and increasing enhancement to achieve single molecule detection. From the mid-1980s to early 1990s, research started to move away from obtaining a fundamental understanding of the phenomenon to the exploration of analytical applications. At the same time, significant developments occurred in the field of photonics that led to the advent of inexpensive, robust, compact, field-deployable Raman systems. The 1990s also saw rapid development in nanoscience. This convergence of technologies (photonics and nanoscience) has led to accelerated development of SERS substrates to detect a wide range of chemical and biological analytes. It would be a monumental task to discuss all the different kinds of SERS substrates that have been explored. Likewise, it would be impossible to discuss the use of SERS for both chemical and biological detection. Instead, a review of the most common metallic (Ag, Cu, and Au) SERS substrates for chemical detection only is discussed, as well as SERS substrates that are commercially available. Other issues with SERS for chemical detection have been selectivity, reversibility, and reusability of the substrates. How these issues have been addressed is also discussed in this review.
411 citations
TL;DR: How nanocellulose and its surface modified versions affects the adsorption behavior of important water pollutants, e.g., heavy metal species, dyes, microbes, and organic molecules is described.
Abstract: Nanocellulose is a renewable material that combines a high surface area with high strength, chemical inertness, and versatile surface chemistry. In this review, we will briefly describe how nanocellulose is produced, and present—in particular, how nanocellulose and its surface modified versions affects the adsorption behavior of important water pollutants, e.g., heavy metal species, dyes, microbes, and organic molecules. The processing of nanocellulose-based membranes and filters for water purification will be described in detail, and the uptake capacity, selectivity, and removal efficiency will also be discussed. The processing and performance of nanocellulose-based membranes, which combine a high removal efficiency with anti-fouling properties, will be highlighted.
338 citations
TL;DR: This review presents a comprehensive update on the challenges of siRNA delivery and the current strategies used to develop nanoparticulate delivery systems.
Abstract: siRNA is a promising therapeutic solution to address gene overexpression or mutations as a post-transcriptional gene regulation process for several pathological conditions such as viral infections, cancer, genetic disorders, and autoimmune disorders like arthritis. This therapeutic method is currently being actively pursued in cancer therapy because siRNA has been found to suppress the oncogenes and address mutations in tumor suppressor genes and elucidate the key molecules in cellular pathways in cancer. It is also effective in personalized gene therapy for several diseases due to its specificity, adaptability, and broad targeting capability. However, naked siRNA is unstable in the bloodstream and cannot efficiently cross cell membranes besides being immunogenic. Therefore, careful design of the delivery systems is essential to fully utilize the potential of this therapeutic solution. This review presents a comprehensive update on the challenges of siRNA delivery and the current strategies used to develop nanoparticulate delivery systems.
293 citations
TL;DR: The focus of this review is to provide an overview of novel nanotechnology-based methods to deliver DNA and small interfering RNAs into biological systems with low cytotoxicity.
Abstract: With the rapid development of nanotechnology in the recent decade, novel DNA and RNA delivery systems for gene therapy have become available that can be used instead of viral vectors. These non-viral vectors can be made of a variety of materials, including inorganic nanoparticles, carbon nanotubes, liposomes, protein and peptide-based nanoparticles, as well as nanoscale polymeric materials. They have as advantages over viral vectors a decreased immune response, and additionally offer flexibility in design, allowing them to be functionalized and targeted to specific sites in a biological system with low cytotoxicity. The focus of this review is to provide an overview of novel nanotechnology-based methods to deliver DNA and small interfering RNAs into biological systems.
273 citations
TL;DR: Mesoporous silica nanoparticles are discussed as biodegradable drug carrier to improve efficacy and reduce side-effects and are a promising tool for innovative, more efficient and safer cancer therapies.
Abstract: Even though cancer treatment has improved over the recent decades, still more specific and effective treatment concepts are mandatory. Surgical removal is not always possible, metastases are challenging and chemo- and radiotherapy can not only have severe side-effects but also resistances may occur. To cope with these challenges more efficient therapies with fewer side-effects are required. One promising approach is the use of drug delivery vehicles. Here, mesoporous silica nanoparticles (MSN) are discussed as biodegradable drug carrier to improve efficacy and reduce side-effects. MSN excellently fulfill the criteria for nanoparticulate carriers: their distinct structure allows high loading capacity and a plethora of surface modifications. MSN synthesis permits fine-tuning of particle and pore sizes. Moreover, drug release can be tailored through various gatekeeper systems which are for example pH-sensitive or redox-sensitive. Furthermore, MSN can either enter tumors passively by the enhanced permeability and retention effect or can be actively targeted by various ligands. PEGylation prolongs circulation time and availability. A huge advantage of MSN is their explicitly low toxic profile in vivo. Yet, clinical translation remains challenging. Overall, mesoporous silica nanoparticles are a promising tool for innovative, more efficient and safer cancer therapies.
272 citations
TL;DR: The latest use of BC in the biomedical field is thoroughly discussed with its applications in both a pure and composite form and the further investigations in the future that are required to make it marketable in vital biomaterials are concluded.
Abstract: Bacterial cellulose (BC) is a highly pure and crystalline material generated by aerobic bacteria, which has received significant interest due to its unique physiochemical characteristics in comparison with plant cellulose. BC, alone or in combination with different components (e.g., biopolymers and nanoparticles), can be used for a wide range of applications, such as medical products, electrical instruments, and food ingredients. In recent years, biomedical devices have gained important attention due to the increase in medical engineering products for wound care, regeneration of organs, diagnosis of diseases, and drug transportation. Bacterial cellulose has potential applications across several medical sectors and permits the development of innovative materials. This paper reviews the progress of related research, including overall information about bacterial cellulose, production by microorganisms, mechanisms as well as BC cultivation and its nanocomposites. The latest use of BC in the biomedical field is thoroughly discussed with its applications in both a pure and composite form. This paper concludes the further investigations of BC in the future that are required to make it marketable in vital biomaterials.
195 citations
TL;DR: The properties of MnO2 nanomaterials with different morphologies are reported, including applications as electrodes in lithium batteries and supercapacitors and the effect of the morphology of nanosized MnO 2 particles on their fundamental features is evidenced.
Abstract: Manganese dioxides, inorganic materials which have been used in industry for more than a century, now find great renewal of interest for storage and conversion of energy applications. In this review article, we report the properties of MnO2 nanomaterials with different morphologies. Techniques used for the synthesis, structural, physical properties, and electrochemical performances of periodic and aperiodic frameworks are discussed. The effect of the morphology of nanosized MnO2 particles on their fundamental features is evidenced. Applications as electrodes in lithium batteries and supercapacitors are examined.
174 citations
TL;DR: The current state of development for the NLCs', PNPs’, and PLNs’ structures, preparation, and applications over the past five years are reviewed to provide the basis for further study on a controlled release drug delivery system.
Abstract: Nanostructured lipid carriers (NLCs) are modified solid lipid nanoparticles (SLNs) that retain the characteristics of the SLN, improve drug stability and loading capacity, and prevent drug leakage Polymer nanoparticles (PNPs) are an important component of drug delivery These nanoparticles can effectively direct drug delivery to specific targets and improve drug stability and controlled drug release Lipid–polymer nanoparticles (PLNs), a new type of carrier that combines liposomes and polymers, have been employed in recent years These nanoparticles possess the complementary advantages of PNPs and liposomes A PLN is composed of a core–shell structure; the polymer core provides a stable structure, and the phospholipid shell offers good biocompatibility As such, the two components increase the drug encapsulation efficiency rate, facilitate surface modification, and prevent leakage of water-soluble drugs Hence, we have reviewed the current state of development for the NLCs’, PNPs’, and PLNs’ structures, preparation, and applications over the past five years, to provide the basis for further study on a controlled release drug delivery system
152 citations
TL;DR: The review summarizes current research in this innovative field and discusses direct solar absorber collectors and methods for improving their performance, followed by a discussion of the various types of nanofluids available and the synthesis techniques used to manufacture them.
Abstract: The global demand for energy is increasing and the detrimental consequences of rising greenhouse gas emissions, global warming and environmental degradation present major challenges. Solar energy offers a clean and viable renewable energy source with the potential to alleviate the detrimental consequences normally associated with fossil fuel-based energy generation. However, there are two inherent problems associated with conventional solar thermal energy conversion systems. The first involves low thermal conductivity values of heat transfer fluids, and the second involves the poor optical properties of many absorbers and their coating. Hence, there is an imperative need to improve both thermal and optical properties of current solar conversion systems. Direct solar thermal absorption collectors incorporating a nanofluid offers the opportunity to achieve significant improvements in both optical and thermal performance. Since nanofluids offer much greater heat absorbing and heat transfer properties compared to traditional working fluids. The review summarizes current research in this innovative field. It discusses direct solar absorber collectors and methods for improving their performance. This is followed by a discussion of the various types of nanofluids available and the synthesis techniques used to manufacture them. In closing, a brief discussion of nanofluid property modelling is also presented.
TL;DR: In this paper, a bio-nanoparticle with complex shape (T4 bacteriophage) that self-assembles on glass substrates upon drying was developed, and the fluid flow regime during the drying process, as well as the final self-assembled structures, were studied using dark-field microscopy, while phage diffusion was analysed by tracking of the phage nanoparticles in the bulk solutions.
Abstract: Nanoparticle self-assembly is a complex phenomenon, the control of which is complicated by the lack of appropriate tools and techniques for monitoring the phenomenon with adequate resolution in real-time. In this work, a label-free technique based on dark-field microscopy was developed to investigate the self-assembly of nanoparticles. A bio-nanoparticle with complex shape (T4 bacteriophage) that self-assembles on glass substrates upon drying was developed. The fluid flow regime during the drying process, as well as the final self-assembled structures, were studied using dark-field microscopy, while phage diffusion was analysed by tracking of the phage nanoparticles in the bulk solutions. The concentrations of T4 phage nanoparticles and salt ions were identified as the main parameters influencing the fluid flow, particle motion and, consequently, the resulting self-assembled structure. This work demonstrates the utility of enhanced dark-field microscopy as a label-free technique for the observation of drying-induced self-assembly of bacteriophage T4. This technique provides the ability to track the nano-sized particles in different matrices and serves as a strong tool for monitoring self-assembled structures and bottom-up assembly of nano-sized building blocks in real-time.
TL;DR: In this research, ZnO nanowires doped with Mn2+ and Co2+ ions were synthesized through a facile and inexpensive hydrothermal approach, in which Mn2-doped and Co1+ ions successfully substituted Zn2+ in the ZnNO crystal lattice without changing the morphology and crystalline structure of ZNO.
Abstract: In this research, ZnO nanowires doped with Mn2+ and Co2+ ions were synthesized through a facile and inexpensive hydrothermal approach, in which Mn2+ and Co2+ ions successfully substituted Zn2+ in the ZnO crystal lattice without changing the morphology and crystalline structure of ZnO. The atomic percentages of Mn and Co were 6.29% and 1.68%, respectively, in the doped ZnO nanowires. The photocatalytic results showed that Mn-doped and Co-doped ZnO nanowires both exhibited higher photocatalytic activities than undoped ZnO nanowires. Among the doped ZnO nanowires, Co-doped ZnO, which owns a twice active visible-light photocatalytic performance compared to pure ZnO, is considered a more efficient photocatalyst material. The enhancement of its photocatalytic performance originates from the doped metal ions, which enhance the light absorption ability and inhibit the recombination of photo-generated electron-hole pairs as well. The effect of the doped ion types on the morphology, crystal lattice and other properties of ZnO was also investigated.
TL;DR: The diverse approaches that have been developed to produce electrospun nanofibres that are able to deliver naturally-derived chemical compounds in a controlled way and to prevent their degradation are described.
Abstract: Over the last 10 years great research interest has been directed toward nanofibrous architectures produced by electrospinning bioactive plant extracts. The resulting structures possess antimicrobial, anti-inflammatory, and anti-oxidant activity, which are attractive for biomedical applications and food industry. This review describes the diverse approaches that have been developed to produce electrospun nanofibres that are able to deliver naturally-derived chemical compounds in a controlled way and to prevent their degradation. The efficacy of those composite nanofibres as wound dressings, scaffolds for tissue engineering, and active food packaging systems will be discussed.
TL;DR: Findings suggest that ZnO nanostructures represent a powerful tool in promoting the acceleration of diverse biological processes, finally leading to the formation of new living tissue useful for organ repair.
Abstract: This review focuses on the most recent applications of zinc oxide (ZnO) nanostructures for tissue engineering. ZnO is one of the most investigated metal oxides, thanks to its multifunctional properties coupled with the ease of preparing various morphologies, such as nanowires, nanorods, and nanoparticles. Most ZnO applications are based on its semiconducting, catalytic and piezoelectric properties. However, several works have highlighted that ZnO nanostructures may successfully promote the growth, proliferation and differentiation of several cell lines, in combination with the rise of promising antibacterial activities. In particular, osteogenesis and angiogenesis have been effectively demonstrated in numerous cases. Such peculiarities have been observed both for pure nanostructured ZnO scaffolds as well as for three-dimensional ZnO-based hybrid composite scaffolds, fabricated by additive manufacturing technologies. Therefore, all these findings suggest that ZnO nanostructures represent a powerful tool in promoting the acceleration of diverse biological processes, finally leading to the formation of new living tissue useful for organ repair.
TL;DR: This review will summarize the controllable architectures of spinel NiCo2O4 fabricated by various approaches, and introduce their performances as supercapacitors due to their excellent electrochemical performance, including superior electronic conductivity and electrochemical activity, together with the low cost and environmental friendliness.
Abstract: In recent years, the research on supercapacitors has ushered in an explosive growth, which mainly focuses on seeking nano-/micro-materials with high energy and power densities. Herein, this review will be arranged from three aspects. We will summarize the controllable architectures of spinel NiCo2O4 fabricated by various approaches. Then, we introduce their performances as supercapacitors due to their excellent electrochemical performance, including superior electronic conductivity and electrochemical activity, together with the low cost and environmental friendliness. Finally, the review will be concluded with the perspectives on the future development of spinel NiCo2O4 utilized as the supercapacitor electrodes.
TL;DR: This review presents different strategies that combine nanoscience and nanotechnology in the polymer world to combat contaminations from bacteria, fungi or algae in health, food, agriculture, and textiles.
Abstract: Infections are one of the main concerns of our era due to antibiotic-resistant infections and the increasing costs in the health-care sector. Within this context, antimicrobial polymers present a great alternative to combat these problems since their mechanisms of action differ from those of antibiotics. Therefore, the microorganisms’ resistance to these polymeric materials is avoided. Antimicrobial polymers are not only applied in the health-care sector, they are also used in many other areas. This review presents different strategies that combine nanoscience and nanotechnology in the polymer world to combat contaminations from bacteria, fungi or algae. It focuses on the most relevant areas of application of these materials, viz. health, food, agriculture, and textiles.
TL;DR: Although currently still at its infancy stage, COFs as an innovative source have paved a new way to meet future challenges in human healthcare and disease theranostic.
Abstract: Covalent organic frameworks (COFs) are newly emerged crystalline porous polymers with well-defined skeletons and nanopores mainly consisted of light-weight elements (H, B, C, N and O) linked by dynamic covalent bonds. Compared with conventional materials, COFs possess some unique and attractive features, such as large surface area, pre-designable pore geometry, excellent crystallinity, inherent adaptability and high flexibility in structural and functional design, thus exhibiting great potential for various applications. Especially, their large surface area and tunable porosity and π conjugation with unique photoelectric properties will enable COFs to serve as a promising platform for drug delivery, bioimaging, biosensing and theranostic applications. In this review, we trace the evolution of COFs in terms of linkages and highlight the important issues on synthetic method, structural design, morphological control and functionalization. And then we summarize the recent advances of COFs in the biomedical and pharmaceutical sectors and conclude with a discussion of the challenges and opportunities of COFs for biomedical purposes. Although currently still at its infancy stage, COFs as an innovative source have paved a new way to meet future challenges in human healthcare and disease theranostic.
TL;DR: This review discusses the environmental behavior of metal-based NPs with an in-depth analysis of the mechanisms and kinetics, and focuses on knowledge gaps in the interaction of NPS with aquatic organisms, which can influence the fate, transport and toxicity of NPs in the aquatic environment.
Abstract: The specific properties of metal-based nanoparticles (NPs) have not only led to rapidly increasing applications in various industrial and commercial products, but also caused environmental concerns due to the inevitable release of NPs and their unpredictable biological/ecological impacts. This review discusses the environmental behavior of metal-based NPs with an in-depth analysis of the mechanisms and kinetics. The focus is on knowledge gaps in the interaction of NPs with aquatic organisms, which can influence the fate, transport and toxicity of NPs in the aquatic environment. Aggregation transforms NPs into micrometer-sized clusters in the aqueous environment, whereas dissolution also alters the size distribution and surface reactivity of metal-based NPs. A unique toxicity mechanism of metal-based NPs is related to the generation of reactive oxygen species (ROS) and the subsequent ROS-induced oxidative stress. Furthermore, aggregation, dissolution and ROS generation could influence each other and also be influenced by many factors, including the sizes, shapes and surface charge of NPs, as well as the pH, ionic strength, natural organic matter and experimental conditions. Bioaccumulation of NPs in single organism species, such as aquatic plants, zooplankton, fish and benthos, is summarized and compared. Moreover, the trophic transfer and/or biomagnification of metal-based NPs in an aquatic ecosystem are discussed. In addition, genetic effects could result from direct or indirect interactions between DNA and NPs. Finally, several challenges facing us are put forward in the review.
TL;DR: It is found that the NiO nanoparticles exhibit a strong green band emission around ~2.37 eV in all samples, covering 80% integrated intensity of PL spectra, which is attributed to photogenerated holes trapped in the deep level oxygen vacancy recombining with the electrons trapped in a shallow level located just below the conducting band.
Abstract: Nickel oxide is one of the highly promising semiconducting materials, but its large band gap (3.7 to 4 eV) limits its use in practical applications. Here we report the effect of nickel/oxygen vacancies and interstitial defects on the near-band-edge (NBE) and deep-level-emission (DLE) in various sizes of nickel oxide (NiO) nanoparticles. The ultraviolet (UV) emission originated from excitonic recombination corresponding near-band-edge (NBE) transition of NiO, while deep-level-emission (DLE) in the visible region due to various structural defects such as oxygen vacancies and interstitial defects. We found that the NiO nanoparticles exhibit a strong green band emission around ~2.37 eV in all samples, covering 80% integrated intensity of PL spectra. This apparently anomalous phenomenon is attributed to photogenerated holes trapped in the deep level oxygen vacancy recombining with the electrons trapped in a shallow level located just below the conducting band.
TL;DR: The results are discussed, along with evidence that demonstrates it is possible to further reduce fouling by taking advantage of the inherent conductivity of composite membranes containing CNTs, as well as by using different types of electrochemical stimuli.
Abstract: Over the course of the past decade, there has been growing interest in the development of different types of membranes composed of carbon nanotubes (CNTs), including buckypapers and composite materials, for an ever-widening range of filtration applications. This article provides an overview of how different types of CNT membranes are prepared and the results obtained from investigations into their suitability for different applications. The latter involve the removal of small particles from air samples, the filtration of aqueous solutions containing organic compounds and/or bacteria, and the separation of individual liquids present in mixtures. A growing number of reports have demonstrated that the incorporation of CNTs into composite membranes confers an improved resistance to fouling caused by biomacromolecules and bacteria. These results are discussed, along with evidence that demonstrates it is possible to further reduce fouling by taking advantage of the inherent conductivity of composite membranes containing CNTs, as well as by using different types of electrochemical stimuli.
TL;DR: The in vitro hyperthermia temperature was reached within 3 min, which shows a very high efficiency and kills nearly all of the experimental MG-63 osteosarcoma cells within 30 min exposure and could potentially open new perceptions for biomaterials that are aimed for anti-cancer therapies based on magnetichyperthermia.
Abstract: Targeting cancer cells without injuring normal cells is the prime objective in treatment of cancer. In this present study, solvothermal and wet chemical precipitation techniques were employed to synthesize iron oxide (IO), hydroxyapatite (HAp), and hydroxyapatite coated iron oxide (IO-HAp) nanoparticles for magnetic hyperthermia mediated cancer therapy. The synthesized well dispersed spherical IO-HAp nanoparticles, magnetite, and apatite phases were confirmed by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and Field emission transmission electron microscopy (FETEM) with Energy Dispersive X-ray spectroscopy (EDS). The non-toxic behavior of synthesized IO-HAp nanoparticles was confirmed by cytotoxicity assay (Trypan blue and MTT assay). The synthesized nanoparticles revealed a remarkable magnetic saturation of 83.2 emu/g for IO and 40.6 emu/g for IO-HAp nanoparticles in presence of 15,000 Oe (1.5 T) magnetic field at room temperature (300 K). The magnetic hyperthermia study that was performed with IO-HAp nanoparticles showed an excellent hyperthermia effect (SAR value 85 W/g) over MG-63 osteosarcoma cells. The in vitro hyperthermia temperature (~45 °C) was reached within 3 min, which shows a very high efficiency and kills nearly all of the experimental MG-63 osteosarcoma cells within 30 min exposure. These results could potentially open new perceptions for biomaterials that are aimed for anti-cancer therapies based on magnetic hyperthermia.
TL;DR: The GONS-cement composites were easy to prepare and exhibited excellent mechanical properties, however, their fluidity decreased with increasing GONS content, and the true hydration mechanism of cement composites with GONSs needs further study.
Abstract: In this work, the effect of graphene oxide nanosheet (GONS) additives on the properties of cement mortar and ultra-high strength concrete (UHSC) is reported. The resulting GONS-cement composites were easy to prepare and exhibited excellent mechanical properties. However, their fluidity decreased with increasing GONS content. The UHSC specimens were prepared with various amounts of GONSs (0-0.03% by weight of cement). Results indicated that using 0.01% by weight of cement GONSs caused a 7.82% in compressive strength after 28 days of curing. Moreover, adding GONSs improved the flexural strength and deformation ability, with the increase in flexural strength more than that of compressive strength. Furthermore, field-emission scanning electron microscopy (FE-SEM) was used to observe the morphology of the hardened cement paste and UHSC samples. FE-SEM observations showed that the GONSs were well dispersed in the matrix and the bonding of the GONSs and the surrounding cement matrix was strong. Furthermore, FE-SEM observation indicated that the GONSs probably affected the shape of the cement hydration products. However, the growth space for hydrates also had an important effect on the morphology of hydrates. The true hydration mechanism of cement composites with GONSs needs further study.
TL;DR: It is proved that adding halloysite filled with Ca(OH)2 to paper can reduce the impact of acid exposure on both the mechanical performance and pH alteration, and have a double effect: they preserve the calcium hydroxide from carbonation, and they prevent from the formation of highly basic pH.
Abstract: Hollow halloysite nanotubes have been used as nanocontainers for loading and for the triggered release of calcium hydroxide for paper preservation. A strategy for placing end-stoppers into the tubular nanocontainer is proposed and the sustained release from the cavity is reported. The incorporation of Ca(OH)2 into the nanotube lumen, as demonstrated using transmission electron microscopy (TEM) imaging and Energy Dispersive X-ray (EDX) mapping, retards the carbonatation, delaying the reaction with CO2 gas. This effect can be further controlled by placing the end-stoppers. The obtained material is tested for paper deacidification. We prove that adding halloysite filled with Ca(OH)2 to paper can reduce the impact of acid exposure on both the mechanical performance and pH alteration. The end-stoppers have a double effect: they preserve the calcium hydroxide from carbonation, and they prevent from the formation of highly basic pH and trigger the response to acid exposure minimizing the pH drop-down. These features are promising for a composite nanoadditive in the smart protection of cellulose-based materials.
TL;DR: The results collectively indicate the successful fabrication of novel antioxidant, antimicrobial IONP@GA composite, which are magnetically separable, efficient, and low cost, with potential applications in polymers, cosmetics, and biomedical and food industries.
Abstract: In this research, we report the size-controlled synthesis and surface-functionalization of magnetite with the natural antioxidant gallic acid (GA) as a ligand, using in situ and post-synthesis methods. GA functionalization provided narrow size distribution, with an average particle size of 5 and 8 nm for in situ synthesis of gallic acid functionalized magnetite IONP@GA1 and IONP@GA2, respectively, which are ultra-small particles as compared to unfunctionalized magnetite (IONP) and post functionalized magnetite IONP@GA3 with average size of 10 and 11 nm respectively. All the IONPs@GA samples were found hydrophilic with stable aggregation state. Prior to commencement of experimental lab work, PASS software was used to predict the biological activities of GA and it is found that experimental antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and antimicrobial studies using well diffusion method are in good agreement with the simulated results. Furthermore, the half maximal inhibitory concentration (IC50) values of DPPH antioxidant assay revealed a 2-4 fold decrease as compared to unfunctionalized IONP. In addition to antioxidant activity, all the three IONP@GA proved outstanding antimicrobial activity while testing on different bacterial and fungal strains. The results collectively indicate the successful fabrication of novel antioxidant, antimicrobial IONP@GA composite, which are magnetically separable, efficient, and low cost, with potential applications in polymers, cosmetics, and biomedical and food industries.
TL;DR: Recent results obtained in the use of SCNPs as bioinspired, highly-efficient nanoreactors for the synthesis of a variety of nanomaterials (inorganic nanoparticles, quantum dots, carbon nanodots), polymers, and chemical compounds, as well as nanocontainers for CO2 capture and release are highlighted.
Abstract: Enzymes are the most efficient catalysts known for working in an aqueous environment near room temperature. The folding of individual polymer chains to functional single-chain nanoparticles (SCNPs) offers many opportunities for the development of artificial enzyme-mimic catalysts showing both high catalytic activity and specificity. In this review, we highlight recent results obtained in the use of SCNPs as bioinspired, highly-efficient nanoreactors (3–30 nm) for the synthesis of a variety of nanomaterials (inorganic nanoparticles, quantum dots, carbon nanodots), polymers, and chemical compounds, as well as nanocontainers for CO2 capture and release.
TL;DR: The formation and properties of ordered, anisotropic fluid phases, liquid crystals, by addition of shape-anisotropic nanomaterials to isotropic liquids are reviewed, including graphene oxide.
Abstract: Liquid crystals are an integral part of a mature display technology, also establishing themselves in other applications, such as spatial light modulators, telecommunication technology, photonics, or sensors, just to name a few of the non-display applications. In recent years, there has been an increasing trend to add various nanomaterials to liquid crystals, which is motivated by several aspects of materials development. (i) addition of nanomaterials can change and thus tune the properties of the liquid crystal; (ii) novel functionalities can be added to the liquid crystal; and (iii) the self-organization of the liquid crystalline state can be exploited to template ordered structures or to transfer order onto dispersed nanomaterials. Much of the research effort has been concentrated on thermotropic systems, which change order as a function of temperature. Here we review the other side of the medal, the formation and properties of ordered, anisotropic fluid phases, liquid crystals, by addition of shape-anisotropic nanomaterials to isotropic liquids. Several classes of materials will be discussed, inorganic and mineral liquid crystals, viruses, nanotubes and nanorods, as well as graphene oxide.
TL;DR: The results showed that as the pH moved away from 6, the size of CuO agglomerates decreased, along with the enhanced NP suspension stabilization, due to the increase of electrostatic repulsive force.
Abstract: Many studies have shown the effect of solution chemistry on the environmental behavior of metal-based nanoparticles (NPs), except CuO NPs. Here, we investigated the agglomeration, sedimentation, dissolution, and speciation of CuO NPs by varying pH, ionic strength, ionic valence, and natural organic matter (NOM). The results showed that as the pH moved away from 6, the size of CuO agglomerates decreased, along with the enhanced NP suspension stabilization, due to the increase of electrostatic repulsive force. Increasing ionic strength and valence intensified the agglomeration and sedimentation of CuO NPs because of the compression of electrical double layers. The presence of humic acid and citric acid enhanced the dispersion and stabilization of CuO NP suspension, but l-cysteine showed a different impact. Decreasing pH, increasing ionic strength and all NOM improved the dissolution of CuO NPs, but the divalent electrolyte (CaCl₂) inhibited the Cu2+ release from CuO NPs compared to the monovalent electrolyte (NaCl). In addition, X-ray absorption near edge structure (XANES) analysis demonstrated that the presence of l-cysteine transformed more than 30% of CuO NPs to Cu(I)-cysteine by coordinating with thiol group. This study can give us an in-depth understanding on the environmental behavior and fate of CuO NPs in the aquatic environment.
TL;DR: Iradiation of samples with a laser having a wavelength falling into the so called “therapeutic window” of the near infrared region allows the reinforcement of the classical antibacterial effect of silver nanoparticles.
Abstract: A layer of silver nanoplates, specifically synthesized with the desired localized surface plasmon resonance (LSPR) features, was grafted on amino-functionalized bulk glass surfaces to impart a double antibacterial action: (i) the well-known, long-term antibacterial effect based on the release of Ag+; (ii) an “on demand” action which can be switched on by the use of photo-thermal properties of silver nano-objects. Irradiation of these samples with a laser having a wavelength falling into the so called “therapeutic window” of the near infrared region allows the reinforcement, in the timescale of minutes, of the classical antibacterial effect of silver nanoparticles. We demonstrate how using the two actions allows for almost complete elimination of the population of two bacterial strains of representative Gram-positive and Gram-negative bacteria.
TL;DR: In this work, copper (Cu) nanoparticles with observable surface plasmonic resonance (SPR) peaks were synthesized by an in-situ method by using chitosan host polymer as a reduction medium and a capping agent for the Cu nanoparticles.
Abstract: In this work, copper (Cu) nanoparticles with observable surface plasmonic resonance (SPR) peaks were synthesized by an in-situ method. Chitosan host polymer was used as a reduction medium and a capping agent for the Cu nanoparticles. The surface morphology of the samples was investigated through the use of scanning electron micrograph (SEM) technique. Copper nanoparticles appeared as chains and white specks in the SEM images. The strong peaks due to the Cu element observed in the spectrum of energy dispersive analysis of X-rays. For the nanocomposite samples, obvious peaks due to the SPR phenomena were obtained in the Ultraviolet-visible (UV-vis) spectra. The effect of Cu nanoparticles on the host band gap was understood from absorption edges shifting of absorption edges to lower photon energy. The optical dielectric loss parameter obtained from the measurable quantities was used as an alternative method to study the band structure of the samples. Quantum mechanical models drawbacks, in the study of band gap, were explained based on the optical dielectric loss. A clear dispersion region was able to be observed in refractive indices spectra of the composite samples. A linear relationship with a regression value of 0.99 was achieved between the refractive index and volume fractions of CuI content. Cu nanoparticles with various sizes and homogenous dispersions were also determined from transmission electron microscope (TEM) images.