Electrochemical corrosion study of chitosan-hydroxyapatite coated dental implant.

Chitosan (Ch) is a naturally occurring biocompatible and bio-degradable material with high corrosion protective capacities for metals in various corrosive media. Hydroxyapatite (HA) is a significant biodegradable and bioactive material. In the present work, chitosan-hydroxyapatite (Ch-HA) composite coatings with various concentrations of chitosan were made on 316L stainless steel (316L SS) using sol-gel dip coating technique. The coatings were characterized by X-ray diffraction (XRD), FTIR, SEM, and electrochemical measurements. The surface morphology results (SEM) of coated implants exposed the fairly dense microstructures having uniformity without cracks and pores indicating that coating was successfully deposited. From electrochemical analyses, it was observed that the value of corrosion current density and the corrosion rate decreased from 6.03 to 0.15 and 5.56-0.13 respectively indicating that 1.5gCh-HA is the best coating concentration. The electrochemical results demonstrated an improvement in the corrosion resistance of 316L SS than the bare one. The decrease in slope and loop area of cyclic voltammograms reveals about improvement in corrosion resistance. This increment in corrosion resistance of the Ch-HA coated SS implant in the artificial saliva is as 1.5gCh-HA > 2gCh-HA >1gCh-HA >0.5gCh-HA. Furthermore, Ch-HA coatings revealed appropriate adhesion with 316L SS substrate for its use in dental implants.

Preparation of celecoxib loaded bioactive glass chitosan composite hydrogels: a simple approach for therapeutic delivery of NSAIDs.

Arthritis causes inflammatory damage to joints and connective tissues. In the treatment of arthritis, precise and controlled drug delivery to the target site is among the frontline research approaches. In the present research work, celecoxib drug and bioactive glass incorporated chitosan hydrogels were fabricated by the freeze gelation method. Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis/differential scanning calorimetry techniques were used to characterize the hydrogels. Different kinetic models were applied to study the drug release kinetics. The celecoxib release was mainly controlled by a Fickian diffusion process followed by the Higuchi model. Maximum 86.2% drug entrapment was observed in 20 mg drug-loaded hydrogel and its swelling ratio was 115.5% in 28 d. Good hydrophilicity, good drug entrapment efficiency, and moderate drug release patterns of hydrogels can make them suitable for sustained drug release. The cytocompatibility of hydrogels was established by performing an MTT assay on the BHK-21 fibroblast cell line. The promising results have proved that hydrogels can be considered potential material for the slow release of anti-inflammatory drug at the target site in arthritis.

To study the synthesis and characterization of SrO-MgO-SiO2 system in biological and dielectric applications.

Ternary ceramic samples comprising SrO-MgO-SiO2 with varying element concentrations were synthesized using the solid-state method and sintered at 800°C. To characterize the properties of the samples, several analysis techniques were employed. X-ray Diffraction (XRD) was utilized for structural analysis, FTIR spectroscopy was used to identify bonds, SEM provided morphological analysis, biocompatibility was assessed through Vitro testing, microhardness was evaluated using Vickers testing, and dielectric analysis was performed to investigate electrical properties. The XRD spectra confirmed the presence of a ternary phase known as Magnesium Strontium Di-silicate [MgSr2Si2O7], with no impurity peaks detected. FTIR spectroscopy indicated the formation of Magnesium silicate, displaying vibrational bands corresponding to SiO4 and MgO, which further confirmed the existence of MgSr2Si2O7 in the samples. The Vitro test results revealed that all samples exhibited biocompatible behavior, with moderate pH and weight loss. SEM images provided insights into the morphology of the system and confirmed the development of an appetite layer on the sample surfaces. The particle size of the samples was measured to be approximately 116.48±9 nm. Vickers hardness testing yielded microhardness values ranging from 378.1 to 400.2 HV. Dielectric constant measurements demonstrated that the AC conductivity of the SrO-MgO-SiO2 system increased as the percentage of Mg doping increased.

Structural, biological investigation of metal (Fe, Cu, Ag)-ceramic composites.

In the present study, five composites based on metals (Ag, Fe, Cu) and ceramic; named as 0.2 Ag, 0.2 Cu, 0.2 Fe, 0.1Ag-0.1Cu, and 0.1Ag-0.1Fe were prepared by the solid-state sintering method. Two different phases of wollastonite: ß-wollastonite (JCPDS No.: 01-076-0186), and α-wollastonite (JCPDS No.:00-031-0300) were identified in all composite. The in vitro bioactivity assay performed in simulated body fluid showed the bioactive behavior of all composites except one having >0.1% Ag concentration. The antibacterial activity test was performed against two pathogenic bacteria Staph. Aureus and Staph. Epidermidis using the agar well diffusion method. Results of antibacterial assays showed that all samples showed antibacterial activity except the 0.2 Fe sample. It was observed that the addition of Ag and Cu provided the inhibitory ability to composites, 0.1Ag-0.1Cu and 0.1Ag-0.1Fe composites are regarded as an optimum composite having better bioactive and antibacterial efficacy as compared to all other composites.

Development of thermoplastic polyurethane/polyaniline-doped membranes for the separation of glycine through electrodialysis.

Recently, membrane-based separation processes, particularly electrodialysis, have attracted attention for the separation and purification of organic and amino acids from animal feedstock waste. In this study, cation exchange membranes were synthesized by making a composite of thermoplastic polyurethane and polyaniline (PANI) via the doping of various aromatic sulfonic acids, such as ß -naphthol sulfonic acid and phenol sulfonic acid. The PANI was prepared using a standard method, which was further used in the composite blending at varying concentrations of 10%-20%. The impact of the concentration of PANI and the nature of the dopant on the membrane characteristics were comparatively studied. The membranes were analyzed by electric conductivity, water swelling, morphological studies (SEM), and thermogravimetric analysis. The membranes were used for the separation of glycine hydrochloride via electrodialysis.

Synthesis of monophasic Ag doped hydroxyapatite and evaluation of antibacterial activity.

The present study aims to synthesized biomaterial that has antibacterial properties. Currently the surgical implants associated infections are a major cause of implant failure. Synthesis of silver doped hydroxyapatite as an antibacterial agent has potential importance to overcome post-surgical infections in a variety of clinical applications. Five silver doped hydroxyapatite Ca10-xAgx(PO4)6(OH)2 (x = 0, 0.1, 0.3, 0.5, 0.7 M) samples were synthesized by precipitation method and sintered at 900 °C to obtain well crystallized structure. No minor phase developed with silver addition, hexagonal hydroxyapatite (JCPDS# 09-432) was the single phase identified in all silver doped hydroxyapatite samples. The lattice parameter a and c changed with increase in silver concentration. The results of in vitro bioactivity revealed the bone bonding ability of silver doped hydroxyapatite samples. The antibacterial test showed that silver doped hydroxyapatite was sensitive to Staphylococcus aureus bacteria. Addition of silver significantly (P < 0.005) increased the antibacterial activity.

Synthesis, characterization of CaF2 doped silicate glass-ceramics.

This paper reports the fabrication and characterization of silicate glass-ceramics doped with (0-12mol%) CaF2. TGA-DSC analysis was carried out to determine the crystallization temperature and stability of glass measured by two glass parameters; Hruby parameter KH=(Tx-Tg)/(TL-Tx) and Weinberg parameter KW=(Tc-Tg)/TL. It was found that with CaF2 doping improved sinterability at low temperature and provided stability to the glass. The XRD pattern exhibits a single phase of combeite and doping of CaF2 cause increase in crystallite size. Microstructure of samples was also improved with CaF2 addition, pores were significantly reduced. After 15days immersion in simulated body fluid all samples developed apatite layer onto its surface. Hence, the addition of CaF2 provided bioactive glass-ceramic material having a low processing temperature.

Development of a novel pH sensitive silane crosslinked injectable hydrogel for controlled release of neomycin sulfate.

Silane crosslinked biopolymer based novel pH-responsive hydrogels were fabricated by blending the cationic (chitosan) and anionic (alginate) polymers with poly(vinyl alcohol). Tetraethoxysilane (TEOS) was used, as a crosslinker in different amounts due to its nonhazardous nature, to study its impact on physical and chemical properties of the prepared injectable hydrogels along with the controlled release of drug. The swelling response of the prepared hydrogels was examined in different solvent media which exhibited decreased swelling ratio with increase in the amount of TEOS. All the fabricated hydrogels represented highest swelling at acidic pH while low swelling at basic and neutral pH. This specific pH sensitive behavior at pH 7 made them an appropriate candidate for the injectable controlled drug delivery in which Neomycin Sulfate (NMS) was successfully loaded on suitable hydrogel (comprising 50µL TEOS) to study its release mechanism. The results revealed that in simulated gastric fluid (SGF), hydrogel released the entire drug (NMS) in initial 30min while in simulated intestinal fluid (SIF), NMS was released in a controlled way up to 83% in 80min. These results endorsed that the hydrogels could be practiced as a smart intelligent material for injectable controlled drug delivery as well as for other biomedical applications at physiological pH.

Effect of Ti(+4) on in vitro bioactivity and antibacterial activity of silicate glass-ceramics.

A novel glass-ceramic series in (48-x) SiO2-36 CaO-4 P2O5-12 Na2O-xTiO2 (where x=0, 3.5, 7, 10.5 and 14mol %) system was synthesized by crystallization of glass powders, obtained by melt quenching technique. The differential scanning calorimetric analysis (DSC) was used to study the non-isothermal crystallization kinetics of the as prepared glasses. The crystallization behaviour of glasses was analyzed under non-isothermal conditions, and qualitative phase analysis of glass-ceramics was made by X-ray diffraction. The in vitro bioactivity of synthesized glass-ceramics was studied in stimulated body fluid at 37°C under static condition for 24days. The formation of hydroxyl-carbonated apatite layer; evident of bioactivity of the material, was elucidated by XRD, FTIR, AAS, SEM and EDX analysis. The result showed that partial substitution of TiO2 with SiO2 negatively influenced bioactivity; it decreased with increase in concentration of TiO2. As Ti(+4) having stronger field strength as compared to Si(+4) so its replacement became the cause for reduction in degradation that in turn improved the chemical stability. The compressive strength was also enhanced with progress addition of TiO2 in the system. The antibacterial properties were examined against Staphylococcus Epidermidis. Strong antibacterial efficacy was observed with the addition of TiO2 in the system.