ABSTRACT
Electrospinning of a heterogeneous solution is difficult to continue because the required process parameters are different for multiple phases. In this study, nanofibrous mats were successfully prepared from a heterogeneous blend of solid cellulose nanocrystals (CNC) and hydroxyapatite nanoparticles (HAp) in a solution mixture of chitosan and gelatin using an electrospinning technique. HAp and CNC were used as filler materials in the nanofibrous mats. Gelatin and chitosan polymer chains in the mats were crosslinked using glutaraldehyde. The fiber diameter was noticed to decrease from around 86 to 43 nm with the increase of electrical conductivity of the spinning solution from 890 to 1166 µS cm-1 and after crosslinking a significant variation in fibers' diameter was noticed. The elemental analysis data showed that around 85% of the HAp used in the spinning solution was passed through the nozzle and the rest of the portion remained settled in the spinning syringe. In the XRD study, the crystallinity of chitosan, HAp and CNC was not observed in the non-crosslinked and crosslinked mats. The TGA analysis showed that the crosslinked mat has no weight retention at 500 °C which is due to its complete amorphous nature. The mats showed single-phase transition temperatures in DSC analysis which proves that no segregation of materials was present in the electrospun fibers. FTIR analysis of the mats showed a new peak at 1205 cm-1 which suggests the Michael addition type reactions to be happened between chitosan and gelatin. Cytotoxicity analysis of the mats on the vero-cell line showed around 95% of cell viability. The prepared mats were applied as wound dressings on a mice model experiment and 50% faster healing of wounds on the mice was noticed for the non-crosslinked mats than the control one.
ABSTRACT
This study describes the fabrication of nanocomposites using electrospinning technique from poly lactic acid (PLA) and nano-hydroxyapatite (n-HAp). The prepared electrospun PLA-nHAP nanocomposite is intended to be used for drug delivery application. A hydrogen bond in between nHAp and PLA was confirmed by Fourier transform infrared (FT-IR) spectroscopy. Degradation study of the prepared electrospun PLA-nHAp nanocomposite was conducted for 30 days both in phosphate buffer solution (PBS) of pH 7.4 and deionized water. The degradation of the nanocomposite occurred faster in PBS in comparison to water. Cytotoxicity analysis was conducted on both Vero cells and BHK-21 cells and the survival percentage of both cells was found to be more than 95%, which indicates that the prepared nanocomposite is non-toxic and biocompatible. Gentamicin was loaded in the nanocomposite via an encapsulation process and the in vitro drug delivery process was investigated in phosphate buffer solution at different pHs. An initial burst release of the drug was observed from the nanocomposite after 1 to 2 weeks for all pH media. After that, a sustained drug release behavior was observed for the nanocomposite for 8 weeks with a release of 80%, 70% and 50% at pHs 5.5, 6.0 and 7.4, respectively. It can be suggested that the electrospun PLA-nHAp nanocomposite can be used as a potential antibacterial drug carrier for sustained drug release in dental and orthopedic sector.
ABSTRACT
A Semi Interpenetrating Polymer Network (semi-IPN) hydrogel was prepared and loaded with an antibiotic drug, gentamicin, to investigate the wound healing activity of this system. The semi-IPN hydrogel was synthesized by combining natural polymer cellulose nanocrystal (CNC) and synthetic polymer polyethylene glycol (PEG) and poly (N,N'-dimethyl acrylamide) (PDMAA), which was initially added as a monomer dimethyl acrylamide (DMAA). CNC was prepared from locally obtained jute fibers, dispersed in a PEG-NaOH solvent system and then mixed with monomer DMAA, where polymerization was initiated by an initiator potassium persulphate (KPS) and cross-linked by N,N'-methylenebisacrylamide (NMBA). The size, morphology, biocompatibility, antimicrobial activity, thermal and swelling properties of the hydrogel were investigated by different characterization techniques. The biocompatibility of the hydrogel was confirmed by cytotoxicity analysis, which showed >95% survival of the BHK-21, Vero cell line. The drug loaded hydrogel showed antimicrobial property by forming 25 and 23 mm zone of inhibition against Staphylococcus aureus (gram-positive) and Escherichia coli (gram-negative) bacteria, respectively, in antimicrobial analysis. At pH 5.5, 76% of the drug was released from the hydrogel within 72 h, as observed in an in vitro drug release profile. In an in vivo test, the healing efficiency of the drug loaded hydrogel was examined on a mice model with dorsal wounds. Complete healing of the wound without any scar formation was achieved in 12 days, which revealed excellent wound healing properties of the prepared drug loaded semi-IPN hydrogel. These results showed the relevance of such a system in the rapid healing of acute wounds.
ABSTRACT
Various toxic chemicals are discharging to the environment due to rapid industrialization and polluting soil, water, and air causing numerous diseases including life-threatening cancer. Among these pollutants, Cr(VI) or hexavalent chromium is one of the most carcinogenic and toxic contaminants hostile to human health and other living things. Therefore, along with other contaminants, the removal of Cr(VI) efficiently is very crucial to keep our environment neat and clean. On the other hand, silica has a lot of room to modify its surfaces as it is available with various sizes, shapes, pore sizes, surface areas etc. and the surface silanol groups are susceptible to design and prepare adsorbents for Cr(VI). This review emphases on the progress in the development of different types of silica-based adsorbents by modifying the surfaces of silica and their application for the removal of Cr(VI) from wastewater. Toxicity of Cr(VI), different silica surface modification processes, and removal techniques are also highlighted. The adsorption capacities of the surface-modified silica materials with other parameters are discussed extensively to understand how to select the best condition, silica and modifiers to achieve optimum removal performance. The adsorption mechanisms of various adsorbents are also discussed. Finally, future prospects are summarized and some suggestions are given to enhance the adsorption capacities of the surface-modified silica materials.
Subject(s)
Water Pollutants, Chemical , Adsorption , Chromium/analysis , Humans , Hydrogen-Ion Concentration , Kinetics , Silicon Dioxide , Water Pollutants, Chemical/analysisABSTRACT
For the first time, we incorporated mesoporous micro-silica (5 µm, pore size = 50 nm) as a filler in epoxy resin aiming to enter polymer into the pore of the silica. As expected, the thermal stability of the composite increased remarkably, followed by noteworthy thermal degradation kinetics when compared to the controlled cured epoxy resin. Composites were prepared by the direct dispersion of modified nano-silica, modified mesoporous micro-silica, unmodified mesoporous micro-silica, non-porous micro-silica, and irregular micro-silica of various pore sizes as fillers in diglycidyl ether of bisphenol-A epoxy resin via ultra-sonication and shear mixing, followed by oven-curing with 4,4-diaminodiphenyl sulfone. DSC and TGA analyses demonstrated a higher glass transition temperature (increased by 3.65-5.75 °C) and very high activation energy for thermal degradation (average increase = 46.2%) was obtained for the same unmodified silica composite compared to pure epoxy, respectively.
ABSTRACT
In recent years, there have been increasingly rapid advances of using bioactive materials in tissue engineering applications. Bioactive materials constitute many different structures based upon ceramic, metallic or polymeric materials, and can elicit specific tissue responses. However, most of them are relatively brittle, stiff, and difficult to form into complex shapes. Hence, there has been a growing demand for preparing materials with tailored physical, biological, and mechanical properties, as well as predictable degradation behavior. Chitosan-based materials have been shown to be ideal bioactive materials due to their outstanding properties such as formability into different structures, and fabricability with a wide range of bioactive materials, in addition to their biocompatibility and biodegradability. This review highlights scientific findings concerning the use of innovative chitosan-based bioactive materials in the fields of tissue engineering, with an outlook into their future applications. It also covers latest developments in terms of constituents, fabrication technologies, structural, and bioactive properties of these materials that may represent an effective solution for tissue engineering materials, making them a realistic clinical alternative in the near future.
ABSTRACT
The amphiphilic polymer-grafted silica was newly prepared as a stationary phase in high-performance liquid chromatography. Poly(4-vinylpyridine) with a trimethoxysilyl group at one end was grafted onto porous silica particles and the pyridyl side chains were quaternized with 1-bromooctadecane. The obtained poly(octadecylpyridinium)-grafted silica was characterized by elemental analysis, diffuse reflectance infrared Fourier transform spectroscopy and Brunauer-Emmett-Teller analysis. The degree of quaternization of the pyridyl groups on the obtained stationary phase was estimated to be 70%. The selective retention behaviors of polycyclic aromatic hydrocarbons including some positional isomers were investigated using poly(octadecylpyridinium)-grafted silica as an amphiphilic polymer stationary phase in high-performance liquid chromatography and results were compared with commercially available polymeric octadecylated silica and phenyl-bonded silica columns. The results indicate that the selectivity toward polycyclic aromatic hydrocarbons exhibited by the amphiphilic polymer stationary phase is higher than the corresponding selectivity exhibited by a conventional phenyl-bonded silica column. However, compared with the polymeric octadecylated silica phase, the new stationary phase presents similar retention behavior for polycyclic aromatic hydrocarbons but different retention behavior particularly for positional isomers of disubstituted benzenes as the aggregation structure of amphiphilic polymers on the surface of silica substrate has been altered during mobile phase variation.
