Showing papers in "Journal of Materials Chemistry B in 2018"

Nanoscale metal-organic frameworks for drug delivery: a conventional platform with new promise.

Abstract: Development of a controllable drug delivery system is imperative and important to reduce the side-effects and enhance the therapeutic efficacy of drugs. Metal–organic frameworks (MOFs) and nanoscale MOFs (NMOFs), as porous hybrids constructed by polydentate bridging ligands and metal-connecting nodes, have attracted significant attention from the scientific community due to their tailorable compositions and structures, excellent porosity, and easier surface modification. Significant progress has been achieved in the past decade, but most attempts still remain in the proof-of-concept stage. This review highlights the latest advances in NMOFs for drug delivery systems and classifies the current drug-loading method into three strategies according to the location of the cargos and cargo-carrier interactions: encapsulation strategy, direct assembly strategy, and post-synthesis strategy. Each feature and the latest advances in these strategies are highlighted. Finally, the challenges and future perspectives in this field have been discussed.

Wearable and flexible sensors for user-interactive health-monitoring devices.

Abstract: Flexible electronic devices that are lightweight and wearable are critical for personal healthcare systems, which are not restricted by time and space. To monitor human bio-signals in a non-invasive manner, skin-conforming, highly sensitive, reliable, and sustainable healthcare monitoring devices are required. In this review, we introduce flexible and wearable sensors based on engineered functional nano/micro-materials with unique sensing capabilities for detection of physical and electrophysiological vital signs of humans. In addition, we investigate key factors for the development of user-interactive healthcare devices that are customizable, wearable, skin-conforming, and monolithic (design), and have long-term monitoring capability with sustainable power sources. Finally, we describe potential challenges of developing current wearable healthcare devices for applications in fitness, medical diagnosis, prosthetics, and robotics.

The great escape: how cationic polyplexes overcome the endosomal barrier.

Abstract: The targeted and efficiency-oriented delivery of (therapeutic) nucleic acids raises hope for successful gene therapy, ie, for the local and individual treatment of acquired and inherited genetic disorders Despite promising achievements in the field of polymer-mediated gene delivery, the efficiency of the non-viral vectors remains orders of magnitude lower than viral-mediated ones Several obstacles on the molecular and cellular level along the gene delivery process were identified, starting from the design and formulation of the nano-sized carriers up to the targeted release to their site of action In particular, the efficient escape from endo-lysosomal compartments was demonstrated to be a major barrier and its exact mechanism still remains unclear Different hypotheses and theories of the endosomal escape were postulated The most popular one is the so-called "proton sponge" hypothesis, claiming an escape by rupture of the endosome through osmotic swelling It was the first effort to explain the excellent transfection efficiency of poly(ethylene imine) Moreover, it was thought that a unique mechanism based on the ability to capture protons and to buffer the endosomal pH is the basis of endosomal escape Recent theories deal with the direct interaction of the cationic polyplex or free polymer with the exoplasmic lipid leaflet causing membrane destabilization, permeability or polymer-supported nanoscale hole formation Both escape strategies are more related to viral-mediated escape compared to the "proton sponge" effect This review addresses the different endosomal release theories and highlights their key mechanism

NIR-I-to-NIR-II fluorescent nanomaterials for biomedical imaging and cancer therapy

Abstract: Near-infrared (NIR) fluorescence imaging, which affords high imaging resolution owing to deep tissue penetration of NIR photons, is an attractive imaging modality for both biomedical research and clinical applications. To further improve the image contrast at increased tissue depth, recently much attention has been focused on the development of NIR-I-to-NIR-II fluorescence imaging, which can remarkably reduce the interference from photon absorption, scattering and tissue autofluorescence with excitation in the 700-950 nm NIR-I window and emission in the 1000-1700 nm NIR-II window. In this review, we highlight recently developed NIR-I-to-NIR-II fluorescent nanomaterials, including silver chalcogenide quantum dots, single-walled carbon nanotubes and polymer nanoparticles. We discuss the advantages of these nanomaterials as fluorescent tags in deep tissue imaging by comparing them with conventional fluorophores, and then survey the implementation of NIR fluorescence imaging with these nanomaterials, including instrumentation, data analysis and surface biofunctionalization of the nanomaterials. Finally, we discuss recent applications of NIR-I-to-NIR-II fluorescent nanomaterials in the biomedical imaging field, with an emphasis on how to use them to achieve simultaneous cancer diagnosis and therapy.

3D printing of ceramic-based scaffolds for bone tissue engineering: an overview

Abstract: Currently, one of the most promising strategies in bone tissue engineering focuses on the development of biomimetic scaffolds. Ceramic-based scaffolds with favorable osteogenic ability and mechanical properties are promising candidates for bone repair. Three-dimensional (3D) printing is an additive manufacturing technique, which allows the fabrication of patient-specific scaffolds with high structural complexity and design flexibility, and gains growing attention. This review aims to highlight advances in 3D printing of ceramic-based scaffolds for bone tissue engineering. Technical limitations and practical challenges are emphasized and design considerations are also discussed.

Recent progress in upconversion luminescence nanomaterials for biomedical applications

Abstract: Upconversion nanoparticles (UCNPs) are one kind of luminescence nanomaterials that convert low energy photons to high energy emissions. These nanomaterials have recently attracted enormous attention due to their unique photophysical properties, such as resistance to photobleaching and photoblinking, low background autofluorescence, and long luminescence lifetime. Owing to these unique advantages, UCNPs have been widely examined for biomedical applications, including biosensing, imaging, and theranostics. In this review, we have first summarized the mechanisms for three generally accepted upconversion luminescence processes, i.e., lanthanide (Ln) doped upconversion luminescence, dye-sensitized upconversion, and triplet-triplet annihilation upconversion, and then discussed recent advancements on the preparation, functionalization, and biomedical applications of each type of UCNPs. The review article finally concludes with our perspectives on UCNPs' emerging and potential biomedical applications in the near future.

Recent developments in smart antibacterial surfaces to inhibit biofilm formation and bacterial infections

Abstract: Since their development over 70 years, antibiotics are still the most effective strategy to treat bacterial biofilms and infections. However, the overuse of antibiotics in human healthcare and industrial applications has resulted in the development of serious antibiotic-resistant bacteria. Therefore, alternative ways to prevent bacteria attachment and biofilm formation are urgently needed. Recently, mediated biofilm formation processes and smart antibacterial surfaces have emerged as promising strategies to prevent and treat bacterial infections. This review discusses the recent progress in biofilm interference and smart antibacterial surfaces. Smart antibacterial and anti-biofilm surfaces should be responsive to the bacterial infection environment, switchable between various antibacterial functions and have a special bio-inspired structure and function. The major topics discussed are: (i) smart anti-biofilm surfaces via the prevention of biofilm formation or promoting mature biofilm dissolution, (ii) smart materials for reversible killing and/or release of bacteria, (iii) smart surfaces responsive to bacterial infection microenvironments or external stimuli and (iv) bio-inspired surfaces with antifouling and bactericidal properties.

Highly stretchable hydrogels for UV curing based high-resolution multimaterial 3D printing

Abstract: We report a method to prepare highly stretchable and UV curable hydrogels for high resolution DLP based 3D printing. Hydrogel solutions were prepared by mixing self-developed high-efficiency water-soluble TPO nanoparticles as the photoinitiator with an acrylamide-PEGDA (AP) based hydrogel precursor. The TPO nanoparticles make AP hydrogels UV curable, and thus compatible with the DLP based 3D printing technology for the fabrication of complex hydrogel 3D structures with high-resolution and high-fidelity (up to 7 μm). The AP hydrogel system ensures high stretchability, and the printed hydrogel sample can be stretched by more than 1300%, which is the most stretchable 3D printed hydrogel. The printed stretchable hydrogels show an excellent biocompatibility, which allows us to directly 3D print biostructures and tissues. The great optical clarity of the AP hydrogels offers the possibility of 3D printing contact lenses. More importantly, the AP hydrogels are capable of forming strong interfacial bonding with commercial 3D printing elastomers, which allows us to directly 3D print hydrogel–elastomer hybrid structures such as a flexible electronic board with a conductive hydrogel circuit printed on an elastomer matrix.

Nitrogen-doped carbon nanodots for bioimaging and delivery of paclitaxel.

Abstract: Carbon nanodots (CNDs) hold great potential in imaging and drug delivery applications. In this study, nitrogen-doped CNDs (NCNDs) were coupled to the anticancer agent paclitaxel (PTX) through a labile ester bond. NCNDs showed excellent cell viability and endowed the NCND-PTX conjugate with good water solubility. The hybrid integrates the optical properties of the nanodots with the anticancer function of the drug into a single unit. Cytotoxicity was evaluated in breast, cervix, lung, and prostate cancer cell lines by the MTT assay while the cellular uptake was monitored using confocal microscopy. NCND-PTX induced apoptosis in cancer cells exhibiting slightly better anticancer activity compared to the drug alone. Moreover, the course of the NCND-PTX interaction with cancer cells was monitored using an xCELLigence system. The NCND-based conjugate represents a promising platform for bioimaging and drug delivery.

Tuning the optical properties of graphene quantum dots for biosensing and bioimaging

Abstract: Due to their low toxicity, excellent biocompatibility and attractive optical properties, graphene quantum dots (GQDs) have attracted significant attention in the analytical and biological fields. The controllable intrinsic nature of graphene nano-sheets, e.g., size, layer, edge state or shape, offer the chance to fabricate GQDs with tunable photoluminescence behaviors. Carboxylic moieties on the surface and edges of GQDs can provide efficient reactive sites for interaction with various polymeric, organic, inorganic and biological species. This not only provides the chance to tune the optical properties of GQDs via facile chemical approaches such as surface modulation and doping, but also makes GQDs eco-friendly alternatives to replace the traditional fluorescent probes in biological assays. This review highlights new insights into the various strategies for tuning the optical features of GQDs, and their employment as attractive and powerful probes for bio-sensing/imaging. The challenges and future perspectives in the related fields are discussed.

Super-strong and tough poly(vinyl alcohol)/poly(acrylic acid) hydrogels reinforced by hydrogen bonding

Abstract: Synthetic hydrogels or water-containing polymeric materials are much inferior to biological tissues and solid plastics in many aspects of mechanical properties; it is a great challenge to develop hydrogels with mechanical properties comparable with or even superior to those of biological tissues and plastics. Here, we report a type of super-strong and tough hydrogen-bonded poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) hydrogel by immersing as-prepared PVA hydrogels in aqueous PAA solutions and then cold-drawing the hydrogels to different strains. The immersing process introduces PAA chains into the PVA hydrogels, which increases the cross-linking density by hydrogen bonding and hence, much improved mechanical properties and low water contents (35.9–40.2 wt%) are observed. The cold-drawing orients the polymer chains, which enables the formation of more and stronger hydrogen bonds. The mechanical properties of cold-drawn gels are dramatically enhanced, with tensile strength and elastic modulus up to 140 and 100 MPa, respectively; also, super-high toughness (117 MJ m−3) and fracture energy (101 kJ m−2) are obtained. Very impressively, the ultra-high tensile strengths of the cold-drawn hydrogels are superior to those of biological tissues and most solid engineered plastics. Characterizations and comparative studies prove that the enhancement of mechanical properties is mainly due to the formation of more hydrogen bonding rather than the loss of water or the change in crystallinity. This study provides a new strategy for preparing super-strong physically cross-linked hydrogels and other polymeric materials. This super-strong and tough hydrogel may find potential applications in biomedical and load-bearing fields.

Black phosphorus analogue tin sulfide nanosheets: synthesis and application as near-infrared photothermal agents and drug delivery platforms for cancer therapy

Abstract: Two-dimensional (2D) inorganic nanomaterials for biomedical applications still face the challenge of simultaneously offering a high photothermal conversion efficiency (PTCE), efficient drug delivery, biocompatibility and biodegradability. Herein, cancer treatment using tin sulfide nanosheet (SnS NS)-based dual therapy nano-platforms (SDTNPs), including photothermal- and chemo-therapy, is demonstrated. SnS, a black phosphorus (BP) analogue binary IV–VI compound, was synthesized using liquid phase exfoliation. SnS NSs comprising 2–4 layers exhibited good biocompatibility and a high PTCE of 39.3%, which is higher than other popular 2D materials. The SnS NSs showed a stable photothermal performance over 2 h of laser irradiation and exhibited ∼14% degradation after 10 h of irradiation. It was also found that SnS NSs show high loading of small molecules such as doxorubicin (DOX) (up to ∼200% in weight). Consequently, the SDTNPs achieved notable tumor therapy through the combination of photothermal- and chemo-therapy both in vitro and in vivo. Our study may pave the way for the biomedical application of SnS and other IV–VI compound-based 2D nanomaterials. Compared with traditional therapies, SnS NS-based laser therapy is green and efficient, due to its biocompatibility, photo-degradability, high efficiency photothermal properties and high drug loading.

Nanomaterial-doped conducting polymers for electrochemical sensors and biosensors

Abstract: Nanomaterial-doped conducting polymers represent a unique class of composite materials that synergizes the advantageous features of nanomaterials and organic conductors, and they have been used in many applications such as electrochemical sensors and energy storage devices. Conducting polymers can be controllably synthesized from various monomers, and during the polymerization process, different nanomaterials offering unique physical and chemical properties can be doped into the formed conducting polymer composites. In this review, we focus on recent advances in electrochemical sensors and biosensors based on conducting polymers doped with various nanomaterials, including carbon nanomaterials, metal or metal oxide nanoparticles and quantum dots. Approaches to fabrication of films of these materials are described and sensing applications for different targets are summarized.

Peroxidase-like activity of MoS2 nanoflakes with different modifications and their application for H2O2 and glucose detection

Abstract: MoS2 nanoflakes (MoS2 NFs) with a diameter of ∼390 nm were obtained by a facile one-pot hydrothermal method and the NFs exhibited intrinsic peroxidase-like activity. After being modified by commonly used biocompatible surfactants including polyethyleneimine (PEI), polyacrylic acid (PAA), polyvinylpyrrolidone (PVP), and cysteine (Cys), the peroxidase-like catalytic activities of MoS2 NFs were investigated by using 3,3′,5,5′-tetramethylbenzidine (TMB) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS) as chromogenic substrates. Compared to the polymer modified MoS2 NFs, Cys functionalized MoS2 NFs exhibited a high catalytic activity toward H2O2 in the presence of TMB or ABTS. Zeta potential and Michaelis–Menten analyses implied that the electrostatic force induced affinity or repulsion between the MoS2 NFs and substrates, as well as surface modifications of the MoS2 NFs played a key role in the catalytic reactions. Notably, a new peroxidase-like catalytic reaction mechanism was proposed based on the formation of a transient state of Cys–MoS2 NFs containing H2O2 and ABTS, and the catalytic reaction could occur because the Cys on the surface of the MoS2 NFs served as an electron transfer bridge between H2O2 and ABTS. Based on this finding, we also established a platform for colorimetric detection of H2O2 and glucose using Cys–MoS2 NFs as a peroxidase substitution. The limit of detection (LOD) was determined to be 4.103 μmol L−1 for H2O2, and the linear range (LR) was from 0 to 0.3 mmol L−1. The LOD for glucose was 33.51 μmol L−1 and the LR was from 0.05 to 1 mmol L−1, which is suitable for biomedical diagnosis. This work provides a new insight into the catalytic mechanism of peroxidase-like MoS2 NFs, and paves the way for enzyme-like nanomaterials to be used for medical diagnosis.

Advances in Plant-derived Edible Nanoparticle-based lipid Nano-drug Delivery Systems as Therapeutic Nanomedicines.

Abstract: Plant-derived edible nanoparticles (PDNPs) are nano-sized membrane vesicles released by edible plants, such as grapefruit, ginger, broccoli, and lemon They are non-toxic, have tissue-specific targeting properties, and can be mass-produced Thus, they have great potential for clinical application PDNPs offer multiple advantages over the currently available drug delivery systems, such as their relatively high internalization rate, low immunogenicity, proven stability in the gastrointestinal (GI) tract, and ability to overcome the blood-brain barrier but not cross the placental barrier In this review, we will discuss these merits of PDNPs and analyze the current issues in PDNP research

Antioxidant activity of nanomaterials

Abstract: Nanomaterials represent one of the most promising frontiers in the research for improved antioxidants. Some nanomaterials, including organic (i.e. melanin, lignin) metal oxides (i.e. cerium oxide) or metal (i.e. gold, platinum) based nanoparticles, exhibit intrinsic redox activity that is often associated with radical trapping and/or with superoxide dismutase-like and catalase-like activities. Redox inactive nanomaterials can be transformed into antioxidants by grafting low molecular weight antioxidants on them. Herein, we propose a classification of nanoantioxidants based on their mechanism of action, and we review the chemical methods used to measure antioxidant activity by providing a rationale of the chemistry behind them.

Self-assembly of collagen-based biomaterials: preparation, characterizations and biomedical applications

Abstract: The desired mechanical and biological performances of collagen that have led to its broad application as a building block in the biomedical field attributed to its intrinsic hierarchical structure from the nanoscale to macroscale, are discussed herein. Modulating the self-assembly process using regulatory factors can lead to obtaining collagenous materials with tuneable functional performance, which can then determine distinctive cellular responses. Herein, we present an overview of the corresponding characterization techniques used to detect the changes in light transmittance, architecture and mechanics during collagen fibrillogenesis. By combining regulatory parameters with characterization methods, researchers can selectively fabricate collagenous biomaterials with various functional responses.

Progress in TiO2 nanotube coatings for biomedical applications: a review

Abstract: Titanium dioxide nanotubes (TNTs) have drawn wide attention and been extensively applied in the field of biomedicine, due to their large specific surface area, good corrosion resistance, excellent biocompatibility, and enhanced bioactivity. This review describes the preparation of TNTs and the surface modification that entrust the nanotubes with better antibacterial property and enhanced osteoblast adhesion, proliferation, and differentiation. Considering the contact between TNTs' surface and surrounding tissues after implantation, the interactions between TNTs (with properties including their diameter, length, wettability, and crystalline phase) and proteins, platelets, bacteria, and cells are illustrated. The state of the art in the applications of TNTs in dentistry, orthopedic implants, and cardiovascular stents are introduced. In particular, the application of TNTs in biosensing has attracted much attention due to its ability for the rapid diagnosis of diseases. Finally, the difficulties and challenges in the practical application of TNTs are also discussed.

3D printing of nanocellulose hydrogel scaffolds with tunable mechanical strength towards wound healing application

Abstract: We present for the first time approaches to 3D-printing of nanocellulose hydrogel scaffolds based on double crosslinking, first by in situ Ca2+ crosslinking and post-printing by chemical crosslinking with 1,4-butanediol diglycidyl ether (BDDE). Scaffolds were successfully printed from 1% nanocellulose hydrogels, with their mechanical strength being tunable in the range of 3 to 8 kPa. Cell tests suggest that the 3D-printed and BDDE-crosslinked nanocellulose hydrogel scaffolds supported fibroblast cells' proliferation, which was improving with increasing rigidity. These 3D-printed scaffolds render nanocellulose a new member of the family of promising support structures for crucial cellular processes during wound healing, regeneration and tissue repair.

Cellulose nanocrystal (CNC)–inorganic hybrid systems: synthesis, properties and applications

Abstract: Cellulose nanocrystal (CNC), a class of sustainable nanomaterial derived from forest and agro-biomass can serve as nature's storage for carbon dioxide. It has many attractive features, such as large specific surface area, high tensile strength and stiffness, abundance of surface hydroxyl groups, and they are also biocompatible, biodegradable and renewable. When dispersed in a polar solvent, they assemble to form multiphase or higher order structures yielding desirable optical and structural properties. They are being explored as templates for the design of a wide range of new functional nanomaterials. CNCs are excellent support for the loading of inorganic nanoparticles (e.g. Ag, Au, Pt, Pd etc.) yielding stable nano-hybrids in aqueous media. Additional surface functionalization of CNCs impart new and attractive physicochemical properties that are being exploited for application in sensors, catalysts, drug delivery vehicles, anti-microbial agents, scaffold for tissue engineering, biomarkers etc. This review provides an overview and future perspective on recent advances in the development on functional CNC–inorganic hybrids with potential applications in biomedical and chemical systems.

Photo-triggered antibacterial and anticancer activities of zinc oxide nanoparticles

Abstract: ZnO nanoparticles (ZnO NPs) have gained more attention in recent years due to their ability to induce the generation of reactive oxygen species (ROS) under light irradiation. Photo-triggered ROS generation by ZnO NPs and the resulting phototoxicity in cells have found use in antibacterial and anticancer applications. This review highlights recent advances in the development of ZnO NPs and hybrid-type functionalized ZnO NPs for photo-triggered antibacterial and anticancer activities. In addition, various chemical modifications including metal doping, metal hybridization, modification with polymers, and sensitization by organic photosensitizers have been further introduced to enhance the photocatalytic efficiency and ROS generation capability of ZnO NPs. The enhanced ROS generation efficiency of modified ZnO NPs consequently increases their antibacterial and anticancer activities. Additionally, we offer some insights into the design and engineering of next-generation ZnO NPs for more effective antibacterial and anticancer applications.

Mitochondria and lysosome-targetable fluorescent probes for HOCl: recent advances and perspectives

Abstract: Hypochlorous acid (HOCl), as one of the reactive oxygen species (ROS), plays an important role in the destruction of pathogens in the immune system However, abnormal concentration of biogenic HOCl can also damage host tissues, and it has been shown to be associated with many diseases Accordingly, detection of HOCl at the subcellular level is important for understanding inflammation and cellular apoptosis Toward this end, in the past few years, a wide variety of fluorescent HOCl probes have been engineered and applied for imaging of HOCl in subcellular organelles In this review, we highlight the representative cases of the fluorescent HOCl probes with mitochondria and lysosome-targetable ability The discussion includes their design strategies, sensing mechanisms, and applications in bio-imaging of HOCl in mitochondria and lysosomes

Development of quantum dot-based biosensors: principles and applications

Abstract: Development of efficient biosensors for sensitive and selective detection of specific biomolecules is crucial to both fundamental biomedical research and clinical diagnosis. Due to their unique and superior optical and electronic properties, such as high brightness, good photostability, broad absorption spectrum, narrow and size-tunable emission spectrum, large Stokes shift, versatile surface modification, and distinctive photoelectrochemical activity, semiconductor quantum dots (QDs) have been regarded as promising and attractive building blocks for the development of efficient biosensors with high sensitivity, good selectively, rapidity and simplicity. In this review, we summarize the progress of QD-based biosensors in the last 5 years (2013–2018) including QD-based fluorescent, bioluminescent, chemiluminescent, photoelectrochemical biosensors, and focus on their basic principles and their applications for the detection of DNAs, microRNAs, proteins, enzymes, and living cells. Moreover, we give new insight into the future direction and challenges in the development of QD-based biosensors.

Multifunctional smart hydrogels: potential in tissue engineering and cancer therapy

Abstract: In recent years, clinical applications have been proposed for various hydrogel products. Hydrogels can be derived from animal tissues, plant extracts and/or adipose tissue extracellular matrices; each type of hydrogel presents significantly different functional properties and may be used for many different applications, including medical therapies, environmental pollution treatments, and industrial materials. Due to complicated preparation techniques and the complexities associated with the selection of suitable materials, the applications of many host-guest supramolecular polymeric hydrogels are limited. Thus, improvements in the design and construction of smart materials are highly desirable in order to increase the lifetimes of functional materials. Here, we summarize different functional hydrogels and their varied preparation methods and source materials. The multifunctional properties of hydrogels, particularly their unique ability to adapt to certain environmental stimuli, are chiefly based on the incorporation of smart materials. Smart materials may be temperature sensitive, pH sensitive, pH/temperature dual sensitive, photoresponsive or salt responsive and may be used for hydrogel wound repair, hydrogel bone repair, hydrogel drug delivery, cancer therapy, and so on. This review focuses on the recent development of smart hydrogels for tissue engineering applications and describes some of the latest advances in using smart materials to create hydrogels for cancer therapy.

An injectable dipeptide–fullerene supramolecular hydrogel for photodynamic antibacterial therapy

Abstract: Photodynamic therapy (PDT) is a promising treatment against multiantibiotic-resistant bacteria with the advantage of a low tendency towards antibiotic resistance. Due to their high PDT efficiencies and superior chemical stabilities, fullerenes have been proposed as effective photosensitizers for the photodynamic inactivation of bacteria. However, the biomedical applications of fullerenes are hindered by their limited aqueous solubility and apparent tendency to undergo aggregation. Herein, we report a hybrid supramolecular hydrogel prepared by the peptide-modulated self-assembly of fullerenes for targeted and sustained photodynamic antibacterial therapy. Aggregation of the fullerene in the hydrogel is largely inhibited through the non-covalent interactions between the peptide and the fullerene. Consequently, the PDT efficiency of the peptide–fullerene hydrogel is highly improved as compared to the untreated fullerene. The incorporation of fullerene profoundly improves the mechanical properties of the hydrogel, making the peptide–fullerene hydrogel a better injectable formulation for biomedical applications. In vitro and in vivo antibacterial results indicate that the peptide–fullerene hydrogels can effectively inhibit multiantibiotic-resistant Staphylococcus aureus and promote wound healing. This study offers a promising paradigm to adapt self-assembling small peptides with integration of multiple functions for biomedical applications.

A lysosome targetable versatile fluorescent probe for imaging viscosity and peroxynitrite with different fluorescence signals in living cells

Abstract: The lysosome, which acts as the cellular recycling centre, is filled with numerous hydrolases that can degrade most cellular macromolecules. The abnormalities of the lysosome are closely associated with diseases, such as Heřmanský-Pudlak syndrome, Griscelli syndrome and Chediak-Higashi syndrome. Studies have shown that abnormal viscosity and the accumulation of reactive oxygen species (ROS) in the lysosome will disorder the normal function of the lysosome. In this research, a versatile fluorescent probe Lyso-NA has been developed for the multi-channel imaging of lysosomal viscosity and peroxynitrite (ONOO-). When excited at 550 nm, the Lyso-NA exhibited about a 50-fold increase in fluorescence at 610 nm and also with the increasing viscosity from 1.0 cP to 1410 cP, and about a 3.5-fold increase in fluorescence at 510 nm (excitation at 440 nm) together with the increasing ONOO-. These satisfactory response properties make it possible to use Lyso-NA to monitor changes in both viscosity and ONOO- inside the lysosome. To achieve its practical application, it was further demonstrated that Lyso-NA exhibits low cytotoxicity, and good cell permeability, and could be used to monitor lysosomal viscosity and ONOO- in living cells.

Recent progress on graphene-based substrates for surface-enhanced Raman scattering applications.

Abstract: Since the intriguing and inspiring discovery of graphene-enhanced Raman scattering (GERS) in 2010, graphene and graphene-based substrates have attracted significant attention in both theoretical research and application exploration of surface-enhanced Raman scattering (SERS); this makes graphene-involved SERS a burgeoning area in many scientific branches. The introduction of graphene not only overcomes some intrinsic drawbacks of SERS, but also has a great synergistic effect with traditional noble metal nanoparticle enhancement substrates and thus greatly improves the sensing performance of SERS and largely expands its application area. To better learn about the recent progress in graphene-based SERS substrates and shed light on future research, an overview of graphene and graphene-based SERS substrates is presented herein. In this review, the role played by graphene in graphene-based SERS substrates is first summarized, and then, the classification and preparation methods of graphene-based substrates are presented, which are helpful for understanding the structure–property relationship. Furthermore, the SERS applications of graphene-based substrates in biomedical areas, including biomolecule detection, bio-imaging, cancer diagnosis and therapy and drug delivery, are highlighted. Other applications in hot-topic areas such as food safety and environmental monitoring are also briefly discussed. Finally, challenges and perspectives on the deficiencies, future development and achievements are presented.

Preparation of mussel-inspired injectable hydrogels based on dual-functionalized alginate with improved adhesive, self-healing, and mechanical properties.

Abstract: Injectable hydrogels have aroused much attention for the advantages such as minimally invasive surgery, avoidance of surgical trauma, and filling and repairing irregularly shaped tissue defects. Mussel-inspired injectable hydrogels can be immobilized on the surface of tissues, resulting in stable biomaterial-tissue integration. However, the commonly used biomimetic mussel-inspired hydrogels are prepared by the oxidation of catechol groups, which involves the introduction or production of cytotoxic substances. Moreover, mussel-inspired hydrogels generally display weak mechanical strength and poor adhesiveness because of the consumption of catechol groups during oxidation. Herein, we described a strategy to prepare mussel-inspired injectable hydrogels via the Schiff base reaction. We grafted dopamine, an adhesive motif discovered in the holdfast pads of mussels, to aldehyde-modified alginate backbones. A series of injectable mussel-inspired adhesive, self-healing hydrogels were fabricated by in situ crosslinking of hydrazide-modified poly(l-glutamic acid) (PLGA-ADH) and dual-functionalized alginate (catechol- and aldehyde-modified alginate, ALG-CHO-Catechol). Also, oxidized ALG-CHO-Catechol hydrogels and PLGA/ALG-CHO hydrogels were prepared for comparison. The effects of the crosslinking method, catechol grafting ratio and solid content on the mechanical properties, self-healing behavior, adhesive properties, and hemostatic ability were investigated. Compared with the observations for oxidized ALG-CHO-Catechol hydrogels, more reasonable gelation time and notably enhanced mechanical properties and adhesive behavior were detected in the PLGA/ALG-CHO-Catechol hydrogel system. The PLGA/ALG-CHO-Catechol hydrogels also displayed clear self-healing ability and good cytocompatibility. The strong bioadhesion endowed the PLGA/ALG-CHO-Catechol hydrogels with superior hemostatic performance. These results suggested that PLGA/ALG-CHO-Catechol hydrogel might have great potential as an antibleeding and tissue repair material.

2D magnetic titanium carbide MXene for cancer theranostics

Abstract: Fast progress of two-dimensional (2D) materials has catalyzed the emergence of diverse new 2D nanosystems for versatile applications, among which 2D MXenes have attracted broad interest but their single functionality significantly restricts their extensive applications, especially in nanomedicine. Herein we report, for the first time, on the construction of superparamagnetic 2D Ti3C2 MXenes for highly efficient cancer theranostics, which is based on the surface chemistry of specific MXenes for the in situ growth of superparamagnetic Fe3O4 nanocrystals onto the surface of Ti3C2 MXenes. These magnetic Ti3C2-IONPs MXene composites exhibit a high T2 relaxivity of 394.2 mM-1 s-1 and efficient contrast-enhanced magnetic resonance imaging of tumors, providing the potential for therapeutic guidance. Importantly, these superparamagnetic MXenes have shown high photothermal conversion efficiency (48.6%) to guarantee the efficient photothermal killing of cancer cells and ablation of tumor tissues, which has been systematically demonstrated both in vitro and in vivo. The high biocompatibility of these elaborately designed magnetic Ti3C2-based MXene composites guarantees their further potential clinical translation. This report paves a new way for the functionalization of MXene-based 2D nanosheets for broadening their novel applications based on the unique surface chemistry of MXenes, especially in theranostic nanomedicine.

Recent advances in nitric oxide delivery for antimicrobial applications using polymer-based systems

Abstract: The nitric oxide (NO) molecule has gained increasing attention in biological applications to combat biofilm-associated bacterial infections. However, limited NO loading, relatively short half-lives of low molecular weight NO donor compounds, and difficulties in targeted delivery of NO have hindered their practical clinical administration. To overcome these drawbacks, the combination of NO and scaffolds based on biocompatible polymers is an effective way towards realizing the practical utility of NO in biomedical applications. In this regard, the present overview highlights the recent developments in NO-releasing polymeric biomaterials for antimicrobial applications, focusing on antibiofilm treatments and the challenges that need to be overcome.