Nanomaterials have emerged as an amazing class of materials that consists of a broad spectrum of examples with at least one dimension in the range of 1 to 100 nm. Exceptionally high surface areas can be achieved through the rational design of nanomaterials. Nanomaterials can be produced with outstanding magnetic, electrical, optical, mechanical, and catalytic properties that are substantially different from their bulk counterparts. The nanomaterial properties can be tuned as desired via precisely controlling the size, shape, synthesis conditions, and appropriate functionalization. This review discusses a brief history of nanomaterials and their use throughout history to trigger advances in nanotechnology development. In particular, we describe and define various terms relating to nanomaterials. Various nanomaterial synthesis methods, including top-down and bottom-up approaches, are discussed. The unique features of nanomaterials are highlighted throughout the review. This review describes advances in nanomaterials, specifically fullerenes, carbon nanotubes, graphene, carbon quantum dots, nanodiamonds, carbon nanohorns, nanoporous materials, core–shell nanoparticles, silicene, antimonene, MXenes, 2D MOF nanosheets, boron nitride nanosheets, layered double hydroxides, and metal-based nanomaterials. Finally, we conclude by discussing challenges and future perspectives relating to nanomaterials.

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Nanomaterials: a review of synthesis methods, properties, recent progress, and challenges

Recent progress in drug delivery

Mesoporous silica nanoparticles for therapeutic/diagnostic applications.

Red blood cell membrane-camouflaged nanoparticles: a novel drug delivery system for antitumor application.

Application of nanoparticles in biofuels: an overview

Mesoporous silica nanoparticles for drug and gene delivery.

Enhancing in vitro dissolution and in vivo bioavailability of fenofibrate by solid self-emulsifying matrix combined with SBA-15 mesoporous silica.

Beta-carotene is important for fortification of nutritional products while its application is limited by instability. The influence of maltodextrin (MDX) on physicochemical properties and stability of beta-carotene emulsions stabilized by sodium caseinate (SC) was investigated. The emulsions were characterized by dynamic light scattering (DLS), laser diffraction (LD), transmission electron microscopy (TEM), rheometer, and turbiscan lab expert. The effects of pH, ionic strength, and freeze-thaw on stability of emulsions were observed. The emulsions could tolerate up to 2 mol/L NaCl or 10 mmol/L CaCl2 and showed Newtonian behavior. The droplet diameter, polydispersity index, and zeta-potential did not change obviously after 3 months storage at 4°C in dark conditions. The emulsions with MDX showed excellent freeze-thaw stability and gave favorite protection for beta-carotene. The retention ratio of beta-carotene in the emulsions with MDX was above 92.1% after 3 months storage while that in the one without MDX was only 62.7%. The study may provide a promising strategy to improve stability of sensitive nutraceuticals without adding synthetic antioxidants. The findings obtained could provide fundamental basis for rational design of emulsion delivery systems when freeze-thawing is required during manufacturing process or storage period.

The Influence of Maltodextrin on the Physicochemical Properties and Stabilization of Beta-carotene Emulsions

Mesoporous silica nanoparticles (MSNs) with large surface area, tunable pore size, and low toxicity can act as suitable vehicles for drug and gene delivery. An MSN/DNA/PEI complex delivery system was prepared by using MSNs to hold plasmid DNA coated with polyethyleneimine (PEI), and the dry powder formulation was produced by freeze-drying with trehalose as lyoprotectant. The MSN/DNA/PEI complexes successfully enhanced the gene expression with about 1.5-fold higher efficiency as compared with the control, and even better effects and lower toxicity were achieved at lower content of PEI. Also, this gene delivery system showed nearly sixfold higher efficiency in the serum-containing condition than the control, so further application of these vehicles in vivo is highly appreciated. Besides, the trehalose containing lyophilized formulation could hold the availability for at least 4 months of storing at room temperature, presenting the potential for industrial production and transportation of gene therapy.

The Serum-Resistant Transfection Evaluation and Long-Term Stability of Gene Delivery Dry Powder Based on Mesoporous Silica Nanoparticles and Polyethyleneimine by Freezing-Drying.

Gene therapy is a promising strategy for treatment of genetically caused diseases. Successful gene delivery requires an efficient carrier to transfer the desired gene into host cells. Recently, mesoporous silica nanoparticles (MSNs) functionalized with 25 kD polyethyleneimine (PEI) were extensively used as gene delivery carriers. However, 25 kD PEI could significantly reduce the safety of the modified MSNs although it is efficient for intracellular delivery of nucleic acids. In addition, limited drug loading remains a challenge for conventional MSNs drug carriers. Hollow mesoporous silica nanoparticles (HMSNs) with high pore volume, tunable pore size, and excellent biocompatibility are attractive alternatives. To make them more efficient, a less toxic 1.8 kD PEI polymer was used to functionalize the HMSNs which have large pore size (~10 nm) and form PEI-HMSNs. Scanning and transmission electron microscopic images showed that HMSNs were spherical in shape and approximately 270 nm in diameter with uniform hollow nanostructures. The maximum loading capacity of green fluorescent protein labeled DNA (GFP-DNA) in PEI-HMSNs was found to be 37.98 mg/g. The loading capacity of PEI-HMSNs was nearly three-fold higher than those of PEI modified solid nanoparticles, indicating that both hollow and large pores contributed to the increase in DNA adsorption. The transfection of GFP-DNA plasmid loaded in PEI-HMSNs was increased two-fold in comparison to that of 25 kD PEI. MTT assays in Lovo cells showed that the cell viability was more than 85% when the concentration of PEI-HMSNs was 120 µg/mL, whereas the cell viability was less than 20% when the 25 kD PEI was used at the same concentration. These results indicated that PEI-HMSNs could be used as a delivery system for nucleic acids due to good biocompatibility, high gene loading capacity, and enhanced gene transfer efficiency.

Xiaoxu Zhang

Papers

Mesoporous silica nanoparticles for drug and gene delivery.

Enhancing in vitro dissolution and in vivo bioavailability of fenofibrate by solid self-emulsifying matrix combined with SBA-15 mesoporous silica.

The Influence of Maltodextrin on the Physicochemical Properties and Stabilization of Beta-carotene Emulsions

The Serum-Resistant Transfection Evaluation and Long-Term Stability of Gene Delivery Dry Powder Based on Mesoporous Silica Nanoparticles and Polyethyleneimine by Freezing-Drying.

Improved Gene Transfer with Functionalized Hollow Mesoporous Silica Nanoparticles of Reduced Cytotoxicity