Osteogenic Differentiation of Mesenchymal Stem Cells with Silica-Coated Gold Nanoparticles for Bone Tissue Engineering.

Multifunctional nanofibrous scaffolds for effective bone tissue engineering (BTE) application must incorporate factors to promote neovascularization and tissue regeneration. In this study, silica-coated gold nanoparticles Au(SiO2) were tested for their ability to promote differentiation of human mesenchymal stem cells (hMSCs) into osteoblasts. Biocompatible poly-ε-caprolactone (PCL), PCL/silk fibroin (SF) and PCL/SF/Au(SiO2) loaded nanofibrous scaffolds were first fabricated by an electrospinning method. Electrospun nanofibrous scaffolds were characterized for fiber architecture, porosity, pore size distribution, fiber wettability and the relevant mechanical properties using field emission scanning electron microscopy (FESEM), porosimetry, determination of water contact angle, measurements by a surface analyzer and tabletop tensile-tester measurements. FESEM images of the scaffolds revealed beadless, porous, uniform fibers with diameters in the range of 164 ± 18.65 nm to 215 ± 32.12 nm and porosity of around 88-92% and pore size distribution around 1.45-2.35 µm. Following hMSCs were cultured on the composite scaffolds. Cell-scaffold interaction, morphology and proliferation of were analyzed by FESEM analysis, MTS (3-(4,5-dimethyl thiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt) and CMFDA (5-choromethyl fluorescein acetate) dye assays. Osteogenic differentiation of MSCs into osteogenic cells were determined by alkaline phosphatase (ALP) activity, mineralization by alizarin red S (ARS) staining and osteocalcin expression by immunofluorescence staining. The results revealed that the addition of SF and Au(SiO2) to PCL scaffolds enhanced the mechanical strength, interconnecting porous structure and surface roughness of the scaffolds. This, in turn, led to successful osteogenic differentiation of hMSCs with improved cell adhesion, proliferation, differentiation, mineralization and expression of pro-osteogenic cellular proteins. This provides huge support for Au(SiO2) as a suitable material in BTE.

Biocompatible Aloe vera and Tetracycline Hydrochloride Loaded Hybrid Nanofibrous Scaffolds for Skin Tissue Engineering.

Aloe vera (AV) and tetracycline hydrochloride (TCH) exhibit significant properties such as anti-inflammatory, antioxidant and anti-bacterial activities to facilitate skin tissue engineering. The present study aims to develop poly-ε-caprolactone (PCL)/ AV containing curcumin (CUR), and TCH loaded hybrid nanofibrous scaffolds to validate the synergistic effect on the fibroblast proliferation and antimicrobial activity against Gram-positive and Gram-negative bacteria for wound healing. PCL/AV, PCL/CUR, PCL/AV/CUR and PCL/AV/TCH hybrid nanofibrous mats were fabricated using an electrospinning technique and were characterized for surface morphology, the successful incorporation of active compounds, hydrophilicity and the mechanical property of nanofibers. SEM revealed that there was a decrease in the fiber diameter (ranging from 360 to 770 nm) upon the addition of AV, CUR and TCH in PCL nanofibers, which were randomly oriented with bead free morphology. FTIR spectra of various electrospun samples confirmed the successful incorporation of AV, CUR and TCH into the PCL nanofibers. The fabricated nanofibrous scaffolds possessed mechanical properties within the range of human skin. The biocompatibility of electrospun nanofibrous scaffolds were evaluated on primary human dermal fibroblasts (hDF) by MTS assay, CMFDA, Sirius red and F-actin stainings. The results showed that the fabricated PCL/AV/CUR and PCL/AV/TCH nanofibrous scaffolds were non-toxic and had the potential for wound healing applications. The disc diffusion assay confirmed that the electrospun nanofibrous scaffolds possessed antibacterial activity and provided an effective wound dressing for skin tissue engineering.

Minocycline Loaded Hybrid Composites Nanoparticles for Mesenchymal Stem Cells Differentiation into Osteogenesis.

Bone transplants are used to treat fractures and increase new tissue development in bone tissue engineering. Grafting of massive implantations showing slow curing rate and results in cell death for poor vascularization. The potentials of biocomposite scaffolds to mimic extracellular matrix (ECM) and including new biomaterials could produce a better substitute for new bone tissue formation. A purpose of this study is to analyze polycaprolactone/silk fibroin/hyaluronic acid/minocycline hydrochloride (PCL/SF/HA/MH) nanoparticles initiate human mesenchymal stem cells (MSCs) proliferation and differentiation into osteogenesis. Electrospraying technique was used to develop PCL, PCL/SF, PCL/SF/HA and PCL/SF/HA/MH hybrid biocomposite nanoparticles and characterization was analyzed by field emission scanning electron microscope (FESEM), contact angle and Fourier transform infrared spectroscopy (FT-IR). The obtained results proved that the particle diameter and water contact angle obtained around 0.54 ± 0.12 to 3.2 ± 0.18 µm and 43.93 ± 10.8° to 133.1 ± 12.4° respectively. The cell proliferation and cell-nanoparticle interactions analyzed using (3-(4,5-dimethyl thiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt) MTS assay (Promega, Madison, WI, USA), FESEM for cell morphology and 5-Chloromethylfluorescein diacetate (CMFDA) dye for imaging live cells. Osteogenic differentiation was proved by expression of osteocalcin, alkaline phosphatase activity (ALP) and mineralization was confirmed by using alizarin red (ARS). The quantity of cells was considerably increased in PCL/SF/HA/MH nanoparticles when compare to all other biocomposite nanoparticles and the cell interaction was observed more on PCL/SF/HA/MH nanoparticles. The electrosprayed PCL/SF/HA/MH biocomposite nanoparticle significantly initiated increased cell proliferation, osteogenic differentiation and mineralization, which provide huge potential for bone tissue engineering.

Breathable Medicine: Pulmonary Mode of Drug Delivery.

Pharmaceutically active compounds require different modes of drug delivery systems to accomplish therapeutic activity without loss of its activity and lead to exhibit no adverse effects. Originating from ancient days, pulmonary mode of drug delivery is gaining much importance compared to other modes of drug delivery systems with respect to specific diseases. Pulmonary drug delivery is a non-invasive route for local and systemic therapies together with more patient convenience, compliance and is a needleless system. In this review, we addressed the vaccine delivery via non- or minimally invasive routes. Polymeric nanoparticles are preferred for use in the pulmonary delivery devices owing to a prolonged retention in lungs. Small site for absorption, mucociliary clearance, short residence time and low bioavailability are some of the limitations in pulmonary drug delivery have been resolved by generating micro- and nano-sized aerosol particles. We have classified the breathable medicine on the basis of available devices for inhalation and also prominent diseases treated through pulmonary mode of drug delivery. Owing to increasing toxicity of pharmacological drugs, the use of natural medicines has been rapidly gaining importance recently. The review article describes breathability of medicines or the pulmonary mode of drug delivery system and their drug release profile, absorption, distribution and efficacy to cure asthma and diabetes.

Highly Stable Bonding of Thiol Monolayers to Hydrogen-Terminated Si via Supercritical Carbon Dioxide: Toward a Super Hydrophobic and Bioresistant Surface.

Oxide-free silicon chemistry has been widely studied using wet-chemistry methods, but for emerging applications such as molecular electronics on silicon, nanowire-based sensors, and biochips, these methods may not be suitable as they can give rise to defects due to surface contamination, residual solvents, which in turn can affect the grafted monolayer devices for practical applications. Therefore, there is a need for a cleaner, reproducible, scalable, and environmentally benign monolayer grafting process. In this work, monolayers of alkylthiols were deposited on oxide-free semiconductor surfaces using supercritical carbon dioxide (SCCO2) as a carrier fluid owing to its favorable physical properties. The identity of grafted monolayers was monitored with Fourier transform infrared (FTIR) spectroscopy, high-resolution X-ray photoelectron spectroscopy (HRXPS), XPS, atomic force microscopy (AFM), contact angle measurements, and ellipsometry. Monolayers on oxide-free silicon were able to passivate the surface for more than 50 days (10 times than the conventional methods) without any oxide formation in ambient atmosphere. Application of the SCCO2 process was further extended by depositing alkylthiol monolayers on fragile and brittle 1D silicon nanowires (SiNWs) and 2D germanium substrates. With the recent interest in SiNWs for biological applications, the thiol-passivated oxide-free silicon nanowire surfaces were also studied for their biological response. Alkylthiol-functionalized SiNWs showed a significant decrease in cell proliferation owing to their superhydrophobicity combined with the rough surface morphology. Furthermore, tribological studies showed a sharp decrease in the coefficient of friction, which was found to be dependent on the alkyl chain length and surface bond. These studies can be used for the development of cost-effective and highly stable monolayers for practical applications such as solar cells, biosensors, molecular electronics, micro- and nano- electromechanical systems, antifouling agents, and drug delivery.

Controlled release of drugs in electrosprayed nanoparticles for bone tissue engineering.

Generating porous topographic substrates, by mimicking the native extracellular matrix (ECM) to promote the regeneration of damaged bone tissues, is a challenging process. Generally, scaffolds developed for bone tissue regeneration support bone cell growth and induce bone-forming cells by natural proteins and growth factors. Limitations are often associated with these approaches such as improper scaffold stability, and insufficient cell adhesion, proliferation, differentiation, and mineralization with less growth factor expression. Therefore, the use of engineered nanoparticles has been rapidly increasing in bone tissue engineering (BTE) applications. The electrospray technique is advantageous over other conventional methods as it generates nanomaterials of particle sizes in the micro/nanoscale range. The size and charge of the particles are controlled by regulating the polymer solution flow rate and electric voltage. The unique properties of nanoparticles such as large surface area-to-volume ratio, small size, and higher reactivity make them promising candidates in the field of biomedical engineering. These nanomaterials are extensively used as therapeutic agents and for drug delivery, mimicking ECM, and restoring and improving the functions of damaged organs. The controlled and sustained release of encapsulated drugs, proteins, vaccines, growth factors, cells, and nucleotides from nanoparticles has been well developed in nanomedicine. This review provides an insight into the preparation of nanoparticles by electrospraying technique and illustrates the use of nanoparticles in drug delivery for promoting bone tissue regeneration.

Biomimetic hybrid nanofibrous substrates for mesenchymal stem cells differentiation into osteogenic cells.

Mimicking native extracellular matrix with electrospun porous bio-composite nanofibrous scaffolds has huge potential in bone tissue regeneration. The aim of this study is to fabricate porous poly(l-lactic acid)-co-poly-(ε-caprolactone)/silk fibroin/ascorbic acid/tetracycline hydrochloride (PLACL/SF/AA/TC) and nanohydroxyapatite (n-HA) was deposited by calcium-phosphate dipping method for bone tissue engineering (BTE). Fabricated nanofibrous scaffolds were characterized for fiber morphology, hydrophilicity, porosity, mechanical test and chemical properties by FT-IR and EDX analysis. The results showed that the fiber diameter and pore size of scaffolds observed around 228±62-320±22nm and 1.5-6.9µm respectively. Resulting nanofibrous scaffolds are highly porous (87-94%) with ultimate tensile strength observed in the range of 1.51-4.86MPa and also showed better hydrophilic properties after addition of AA, TC and n-HA. Human mesenchymal stem cells (MSCs) cultured on these bio-composite nanofibrous scaffolds and stimulated to osteogenic differentiation in the presence of AA/TC/n-HA for BTE. The cell proliferation and biomaterial interactions were studied using MTS assay, SEM and CMFDA dye exclusion methods. Osteogenic differentiation of MSCs was proven by using alkaline phosphatase activity, mineralization and double immunofluorescence staining of both CD90 and osteocalcin. The observed results suggested that the fabricated PLACL/SF/AA/TC/n-HA biocomposite hybrid nanofibrous scaffolds have good potential for the differentiation of MSCs into osteogenesis for bone tissue engineering.

Deposition of zwitterionic polymer brushes in a dense gas medium.

Poly(sulfobetaine methacrylate) (PSBMA) films known for their resistance to nonspecific protein adsorption, cell/bacterial adhesion and biofilm formation were produced by surface initiated polymerization on a silicon surface via a batch reaction system in CO2 expanded liquid (CO2-EL) medium. Atom transfer radical polymerization (ATRP) was carried out using 2,2'-bipyridyl as ligand and CuBr as a catalyst in water/methanol mixture with trichloro[4-(chloromethyl)phenyl]silane (CMPS) used as the initiating species. The films were grown in the CO2-EL environment at a range of conditions and thickness up to 10nm. In contrast to films produced by conventional solvent systems at atmospheric pressure, the polymer films grown by the CO2-EL process showed uniform thickness and pin-hole free topography. Most importantly, the CO2-EL processed PSBMA films showed no trace of copper (used as the catalyst), thus obviating the need for post-deposition processing and avoiding adverse effects of the metal leaching during service. Finally, PSBMA films from both the conventional and CO2-EL processes were exposed to Human mesenchymal stem cells (hMSCs) and the results showed that, while in both the cases the cell proliferation rate was inhibited by the charged polymeric brush surface, the CO2-EL-processed brush exhibited inhibition to a larger extent due to the reduced occurrence of pinholes. The process can be easily exploited effectively when carrying out surface initiated polymerization on non-flat topographies, such as in trenches and nanostructured features with high aspect ratios.

Biocomposite nanofibrous strategies for the controlled release of biomolecules for skin tissue regeneration.

Nanotechnology and tissue engineering have enabled engineering of nanostructured strategies to meet the current challenges in skin tissue regeneration. Electrospinning technology creates porous nanofibrous scaffolds to mimic extracellular matrix of the native tissues. The present study was performed to gain some insights into the applications of poly(l-lactic acid)-co-poly-(ε-caprolactone) (PLACL)/silk fibroin (SF)/vitamin E (VE)/curcumin (Cur) nanofibrous scaffolds and to assess their potential for being used as substrates for the culture of human dermal fibroblasts for skin tissue engineering. PLACL/SF/VE/Cur nanofibrous scaffolds were fabricated by electrospinning and characterized by fiber morphology, membrane porosity, wettability, mechanical strength, and chemical properties by Fourier transform infrared (FTIR) analysis. Human dermal fibroblasts were cultured on these scaffolds, and the cell scaffold interactions were analyzed by cell proliferation, cell morphology, secretion of collagen, expression of F-actin, and 5-chloromethylfluorescein diacetate (CMFDA) dye. The electrospun nanofiber diameter was obtained between 198±4 nm and 332±13 nm for PLACL, PLACL/SF, PLACL/SF/VE, and PLACL/SF/VE/Cur nanofibrous scaffolds. FTIR analysis showed the presence of the amide groups I, II, and III, and a porosity of up to 92% obtained on these nanofibrous scaffolds. The results showed that the fibroblast proliferation, cell morphology, F-actin, CMFDA dye expression, and secretion of collagen were significantly increased in PLACL/SF/VE/Cur when compared to PLACL nanofibrous scaffolds. The accessibility of human dermal fibroblasts cultured on PLACL/SF/VE/Cur nanofibrous scaffolds proved to be a potential scaffold for skin tissue regeneration.

Mimicking nanofibrous hybrid bone substitute for mesenchymal stem cells differentiation into osteogenesis.

Mimicking hybrid extracellular matrix is one of the main challenges for bone tissue engineering (BTE). Biocompatible polycaprolactone/poly(α,ß)-DL-aspartic acid/collagen nanofibrous scaffolds were fabricated by electrospinning and nanohydroxyapatite (n-HA) was deposited by calcium phosphate dipping method for BTE. Human mesenchymal stem cells (hMSCs) were cultured on these hybrid scaffolds to investigate the cell proliferation, osteogenic differentiation by alkaline phosphatase activity, mineralization, double immunofluorescent staining using CD90 and expression of osteocalcin. The present study indicated that the PCL/PAA/collagen/n-HA scaffolds promoted greater osteogenic differentiation of hMSCs, proving to be a potential hybrid scaffolds for BTE.