Existence Of Hydroxyl Research Articles

Biofilm inhibition of Staphylococcus aureus by silver nanoparticles derived from Hellenia speciosa rhizome extract

Staphylococcus aureus is the most common cause of serious health conditions because of the formation of biofilm, which lowers antibiotic efficacy and enhances infection transmission and tenacious behavior. This bacteria is a major threat to the worldwide healthcare system. Silver nanoparticles have strong antibacterial characteristics and emerged as a possible alternative. This work is most relevant since it investigates the parameters influencing the biogenic nanoparticle-assisted control of bacterial biofilms by Staphylococcus aureus.Nanoparticles were fabricated utilizing Hellenia speciosa rhizome extracts, which largely comprised physiologically active components such as spirost-5-en-3-yl acetate, thymol, stigmasterol, and diosgenin, enhanced with the creation of silver nanocomposites. GC-MS, XRD, DLS, SEM, EDX, FTIR and TEM were used to investigate the characteristics of nanoparticles. The microtiter plate experiment showed that nanoparticles destroyed biofilms by up to 92.41 % at doses that ranged from 0 to 25 μg/ml. Fluorescence microscopy and SEM demonstrated the nanoparticles' capacity to prevent bacterial surface adhesion. EDX research revealed that the organic extract efficiently formed silver nanoparticles with considerable oxygen incorporation, which was attributed to phytochemicals that stabilize AgNPs and prevent accumulation. FTIR spectroscopy indicated the existence of hydroxyl, carbonyl, and carboxylate groups, which are essential for nanoparticle stability. TEM revealed that the AgNPs were spheroidal, with diameters ranging from 40 to 60 nm and an average of 46 nm. These results demonstrate the efficacy of H. speciosa extract in creating stable, well-defined AgNPs suited for a variety of applications. This work underlines the potential of green-synthesized AgNPs in biomedical applications, notably in the treatment of S. aureus biofilm-associated illnesses. The thorough characterization gives important information on the stability and efficiency of these biogenic nanoparticles.

Robust unsymmetric pincer-type Ru(II) catalyst containing proton-responsive hydroxypyridyl fragment for β-alkylation of secondary alcohols with primary alcohols

A highly efficient metal-ligand bifunctional pincer-type Ru(II) catalyst (LOH-Ru-Cl) containing proton-responsive 2-hydroxypyridyl group has been designed and synthesized. The as-synthesized Ru(II) catalyst was definitely characterized by single-crystal X-ray diffraction. The developed Ru(II) catalyst exhibited excellent performance for the β-alkylation of secondary alcohols with primary alcohols. The optimized experiments have demonstrated that the existence of hydroxyl (-OH) group, as well as its position contained in pyridine ligand are crucial for the β-alkylation reaction. As far as we know, this is the first investigation towards the effect of position of hydroxyl (-OH) group contained in unsymmetric pincer-type catalyst on the performance of β-alkylation. The developed LOH-Ru-Cl catalyst may provide an enlightening role for synthesis of Ru(II) catalyst contained various position of hydroxyl (-OH) groups for industrial β-alkylation reactions.

Synthesis and Characterization of Activated Carbons Prepared from Agro-Wastes by Chemical Activation

In this present study, activated carbons were prepared from rice husks and potato peels by chemical activation with 40% phosphoric acid (H3PO4). The effects of carbonization temperature and impregnation ratio were investigated with a continuous activation period. Physicochemical characteristics such as surface morphology, surface charge, and surface functional groups were assessed. According to X-ray diffraction measurements, the results showed that the activated carbons had identical pHpzc (6.8) and that the activated carbons generated were carbonaceous. The existence of hydroxyl, carbonyl, amines, aromatic, and other functional groups, which are excellent for adsorption, was revealed by surface chemistry studies. Micrographs taken with a scanning electron microscope indicated wide opening pores with a larger mesoporous surface area and many linked pores. Rice husk activated carbon outperformed potato peel activated carbon in laboratory tests. The research has shown that the agro-wastes employed in the study are possible precursors for making locally activated carbons at a low cost, thus resolving the problem of agro-waste disposal.

Role of Cysteine in Enhanced Degradation of Trichloroethane under Ferrous Percarbonate System

The removal of toxic contaminants such as trichloroethane (TCA) from groundwater had a huge impact due to associated health hazards. Advanced oxidation technology has an outstanding potential to remove these toxins. However, the redox cycling of Fe(II)/Fe(III) is mostly a barrier for the efficient removal of these contaminants. In this study, we extracted two in one nature of cysteine (CYS) to enhance TCA degradation in Fe(II)/sodium percarbonate (SPC) system. The chelating and reducing capability of CYS, concentration impact of Fe(II), SPC, and pH role were all thoroughly investigated. The existence of hydroxyl (OH●) and superoxide (O2–●) radicals were confirmed through quencher tests. Furthermore, the electron paramagnetic resonance (EPR) spectra evaluated the enhancement of OH● radicals in the Fe(II)/CYS/SPC system due to the electron transfer capability of CYS. The Fe(II)/CYS/SPC showed excellent recyclability and stability characteristics up to 68% TCA degradation in the fourth round. The degradation products and dechlorination analysis confirmed the existence of non-toxic final products. Similarly, the system demonstrated admirable performance in a real groundwater system, bolstering its real-time industrial applications. Conclusively, Fe(II)/CYS/SPC can be a viable and effective method for degrading chlorinated organic hydrocarbons in groundwater.

The photothermal stability of CNFs/ZnAl-LDHs composited films: Influence of the crystal morphology of ZnAl-LDHs

The existence of hydroxyl and carboxyl groups makes the photothermal stability of cellulose nanofibers (CNFs) poor and thus limits its scale application. This problem could be solved by doping layered double hydroxides (LDHs) nanopowders with opposite charge on the surface of CNFs. This work mainly focused on investigation of the influence of the crystal morphology of the inorganic ultraviolet shielding agent (i.e. ZnAl-LDHs) on the thermal stability of CNFs/ZnAl-LDHs composited films. The results showed that the morphology of LDHs was positively correlated with the photothermal stability of CNFs-based films. Specially, the ZnAl-LDHs with uniform crystal morphology could be prepared by controlling the molar ratio of Zn/Al at 3:1 and thus enhance the photothermal stability of CNFs-based films without any serious light transmittance deteriorating after doping. This work provided a practical and effective way for preparation of photothermal-stable CNFs-based transparent films for industrial application in the fields of photonics and electronics.

Alleviating the toxicity of quantum dots to Phanerochaete chrysosporium by sodium hydrosulfide and cysteine.

Quantum dots (QDs) have caused large challenges in clinical tests and biomedical applications due to their potential toxicity from nanosize effects and heavy metal components. In this study, the physiological responses of Phanerochaete chrysosporium (P. chrysosporium) to CdSe/ZnS QDs with either an inorganic sulfide NaHS or an organic sulfide cysteine as antidote have been investigated. Scanning electron microscope analysis showed that the hyphal structure and morphology of P. chrysosporium have obviously changed after exposure to 100nM of COOH CdSe/ZnS 505, NH2 CdSe/ZnS 505, NH2 CdSe/ZnS 565, or NH2 CdSe/ZnS 625. Fourier transform infrared spectroscopy analysis indicated that the existence of hydroxyl, amino, and carboxyl groups on cell surface could possibly conduct the stabilization of QDs in an aqueous medium. However, after NaHS or cysteine treatment, the cell viability of P. chrysosporium exposed to CdSe/ZnS QDs increased as compared to control group, since NaHS and cysteine have assisted P. chrysosporium to alleviate oxidative damage by regulating lipid peroxidation and superoxide production. Meanwhile, NaHS and cysteine have also stimulated P. chrysosporium to produce more antioxidant enzymes (superoxide dismutase and catalase), which played significant roles in the defense system. In addition, NaHS and cysteine were used by P. chrysosporium as sulfide sources to promote the glutathione biosynthesis to relieve CdSe/ZnS QDs-induced oxidative stress. This work revealed that sulfide sources (NaHS and cysteine) exerted a strong positive effect in P. chrysosporium against the toxicity induced by CdSe/ZnS QDs.

Secondary metabolites from the resins of Aloe vera and Commiphora mukul mitigate lipid peroxidation.

Oxidative stress is often considered detrimental for cellular processes and damaging for the lipid bi-layer. Counteracting such stresses with the aid of nature-based chemical constituents can be an ideal therapeutic approach. The current study aimed to investigate the chemical constituents of resins derived from the well-known Aloe vera and less known Commiphora mukul trees and their effect in mitigating the lipid peroxidation (LPO) process. The bio-guided isolation of bio-active fractions from both resins afforded 20 chemical constituents (17 from A. vera and 3 from C. mukul). These compounds belonged to anthraquinones, anthraquinone glycosides, quinones, coumarins, polypodane-type terpenoids and benzene derivatives. Major chemical constituents of the resins of A. vera and C. mukul were from the classes of quinones and terpenoids. Feroxidin (4, from A. vera) showed slightly higher inhibition (IC50 = 201.7 ± 0.9 µmol L-1) than myrrhanone C (18, from C. mukul: IC50 = 210.7 ± 0.0 µmol L-1) and methyl 3-(4-hydroxyphenyl) propionate from A. vera (13, IC50 = 232.9 ± 0.2 µmol L-1) compared to the other compounds. Structure-activity relationship showed that the existence of hydroxyl, methoxy and ether groups might play a major role in countering oxidative stress. To the best of our knowledge, anti-LPO activities of compounds 1-4, 14, 18 and 20 are reported for the first time. Such chemical constituents with high anti-lipid peroxidation activity could be helpful in synthesizing candidate drugs.

Performance of biochar-based filtration bed for the removal of Cr(VI) from pre-treated synthetic tannery wastewater

ABSTRACT In the present study, the performance of biochar-based filtration bed was assessed to enhance the removal efficiency of Cr(VI), from the pre-treated synthetic tannery wastewater. The pre-treatment of wastewater was carried out with aluminium formate (AF) as a coagulant and 80% Cr(VI) removal was observed which might be due to the formation of carboxylic complexation reaction. The purity of coagulant and the sludge components were validated with XRD analysis and the results revealed the formation of pure aluminium formate compound as well as a clear change in the crystalline structure in the treated sludge. FT-IR spectra demonstrated the carboxylic compound participated in the removal of Cr(VI) during the coagulation process. The pre-treated wastewater having 20 mg/L (residual) Cr(VI) was passed through a three-layered filtration bed containing biochar, which showed complete removal of Cr(VI) ∼ 99.99% by precipitating into bind form under the influence of CaCO3 and formate ions. The possible mechanistic approach might be due to the presence of formate ions in the pre-treated wastewater, the precipitation of Cr(VI) occurred in the form of Cr(OH)2 by the release of bicarbonate (HCO3−), carbonate ion (CO3 2−) and hydroxide (OH−) ions in the filtration bed. The properties of the biochar were investigated by XRD and FTIR analysis and the results revealed the existence of hydroxyl, carboxyl and carbonyl groups, which participated during the removal of Cr(VI). The results suggest that biochar-based filtration bed could be a promising method for the treatment of pre-treated tannery wastewater.

Flocculating, emulsification and metal sorption properties of a partial characterized novel exopolysaccharide produced by Rhizobium tropici SRA1 isolated from Psophocarpus tetragonolobus (L) D.C.

A novel exopolysaccharide (EPS) was produced by a bacterium which was isolated from Psophocarpus tetragonolobus (L) D.C. and identified as 99% Rhizobium tropici SRA1 by 16S rDNA sequencing. The flocculating performances along with emulsifying activity began simultaneously with the growth and the production of EPS and reached its utmost at 28h. EPS was purified via chilled ethanol precipitation followed by dialysis and lyophilization. The existence of hydroxyl, methoxyl, and carboxylic functional groups were confirmed by Fourier transform infrared (FT-IR) spectrum. EPS was found to be compose of 82.44% neutral sugar and 15.93% uronic acid. The average molecular weight of the exopolysaccharide was estimated as ~ 1.8 × 105. Gas-liquid chromatography indicated the presence of glucose and galactose at a molar ratio of 3:1 in EPS. In the pH range of 3-5 with EPS dosage of 15mg/l at 30°C, cation-independent flocculation greater than 90% was observed. Emulsification indices (E24) of EPS were observed as 86.66%, 83.33%, 76.66%, and 73.33% with olive oil, kerosene, toluene, and n-hexane respectively. Biosorption of Cu K [45.69wt%], Cu L [05.67wt%], Co K [15.58wt%], and Co L [11.72wt%] by EPS was confirmed by energy-dispersive X-ray spectroscopy (EDS). This report on the flocculating, emulsifying, and metal sorption properties of EPS produced by R. tropici SRA1 is unique in the literature.

Fe-TiOx nanoparticles on pineapple peel: Synthesis, characterization and As(V) sorption

Effective Fe-TiOx magnetic nanoparticles were synthesized on pineapple-peel (CPa-Fe/TiOx) to evaluate their As(V) uptake capacity. The nanocomposite was characterized by means of BET surface analysis, SEM, TEM, XRD, FTIR and XPS. The results indicated the obtention of spherical nanoparticles with 5.7 nm of diameter distributed on the surface of pineapple peel with a Ti:Fe molar ratio of 2:1, while DRX indicate that the material is amorphous. IR spectra of the obtained CPa-Fe/TiOx present a number of bands at 3316, 2924, 2852, 1729, 1632, 1371, 1241, 1035, 590 and 545, indicating the existence of hydroxyl and carboxyl groups on the composite material. The nanocomposite was evaluated as an adsorbent of As(V) and experimental parameters as time, pH, concentration and temperature were evaluated. CPa-Fe/TiOx were effective at pH = 5.5, sorption isotherms showed that sorption capacities of the Fe-TiOx, were dependent on the site density, surface area and temperature change. The equilibrium data was modelled with the help of Langmuir and Freundlich equations, based on the values of correlation coefficients (R2) the Langmuir isotherm equation was excellently fitted to the experimental data of the arsenic adsorption with a maximum adsorption uptake of 40 mg/g under the studied conditions. The thermodynamic results showed that the sorption of As(V) onto CPa-Fe/TiOx was feasible, spontaneous and exothermic, through mechanism ligand effect-surface, with the interaction between oxy-hydroxides of Fe and Ti with oxy-anions of arsenic present in solution.

Hydrogen-assisted versus hydroxyl-assisted CO dissociation over Co-doped Cu(111): A DFT study

First principle based density functional theory (DFT) was used to calculate the step-by-step hydrogenation and dissociation reaction network of carbon monoxide (CO) over Co-doped Cu(111) surface as a model for understanding the lateral interaction of surface hydroxyl species (OH) on these reactions. We discussed the CO bond length and the adsorption energy changes of reaction intermediates under different adsorption circumstances for purpose of making out the effect of surface hydroxyl on the reaction selectivity. Reaction intermediates co-adsorbed with H atom and hydroxyl could undergo H-assisted or OH-assisted routes. The calculations show that the OH-assisted route prefers with the formation of COH, CHOH and CH2OH while general H-assisted route prefers with the formation of HCO, CH2O and CH3O. Considering the rather low activation barrier of COH, CHOH and CH2OH to form CHX, the existence of hydroxyl on the surface is in favor of boosting the CHX and suppressing the methanol.

The influence of Yttrium on leakage current and dielectric properties of amorphous Al2O3 thin film derived by sol–gel

Amorphous Yttrium-doped aluminum oxide thin films were deposited on Pt/Ti/SiO2/Si substrates by sol–gel. It was observed by field emission scanning electron microscope that the surface morphology was smooth and homogeneous. From Fourier Transform Infrared Spectroscopy, a broad absorption band at 700–1000 cm−1 owing to vibrations of aluminum oxide was observed. The absorption peaks strength relating to hydroxyl group decreased with the increase of Y doping concentration. The electrical properties were investigated in terms of Y doping content and relative humidity. The results show that the existence of hydroxyl and absorbed water makes a significant influence on the electric properties of films. The electric conduction characteristics and dielectric breakdown properties are modified by the decrease of content of hydroxyl and absorbed water, leading to a lower leakage current and higher dielectric strength. It can be seen that the leakage current of films decreases with the Y doping, and could be reasonably deduced that leakage current can be effectively tuned by Y doping.

Enhanced cavitation–oxidation process of non-VOC aqueous solution using hydrodynamic cavitation reactor

Collapse of cavitation bubbles generates extremely high local pressures and temperatures that can be utilized for generating hydroxyl radicals as strong oxidizing agents. The existence of hydroxyl is known as a main reason for the chemical degradation of solute molecules. In this paper, the operating pressure, inlet pressure, flow rate, and consequently cavitation number in a venturi type hydrodynamic cavitation reactor were controlled and systematically varied. In the case of non-VOC solutions, it is difficult to obtain great extension degradation with just cavitation or that the removal is limited to small percentage. Instead, the contribution of cavitation flow and H2O2 injection, called enhanced cavitation–oxidation process (ECOP) was introduced for the degradation of non-VOC solutions. In this regard, effects of the cavitation number, injection duration, and quantity of H2O2 injection on degradation rate of 2-Chlorophenol were investigated. It was experimentally demonstrated that the degradation rate of 2-Chlorophenol increased with an increase in the injected amount of H2O2. A similar effect was also observed when injection duration was reduced for a fixed quantity of H2O2. In addition, effects of H2O2 injection on cavitation regime and extent of cavitation zone were studied. Moreover, it was found that the injected amount of H2O2 had a major effect on the degradation of 2-Chlorophenol compared to the minor effect of cavitation number over the entire range of cavitation number. Comprehensive yield efficiency analysis was also performed, which showed that, for an energy efficient operation, ECOP was required to operate with mild cavitating flow, high injected magnitude of H2O2, and short injection duration; however, for fast decomposing ECOP, intense cavitating flow was required.

Mechanical Properties of Epoxy Resin/PMMA/SiO2 Dental Composites

Abstract Epoxy resin/ Thermoplastic polymethyl methacrylate (PMMA)/SiO2 dental composites were synthesized successfully at last after the following two steps: polymerization of MMA act as the initiator at this first process. Then the obtained PMMA was incorporated into epoxy resin and SiO2 to prepare the hybrid thermosets. The structural characteristics of epoxy resin/PMMA/SiO2 composites were characterized by Fourier transform infrared spectroscopy (FT–IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). What is more, the mechanical properties and water solubility of the composites have also been tested. It is found that the stability has been improved after adding SiO2 nanoparticles. In addition, the mechanical properties of composites which were modified by silica indicated that the mechanical properties of materials could be improved after preprocessing of SiO2 nanoparticles in epoxy resin/PMMA composites. Interference of epoxy resin produced magnetic adsorption and chemical reaction with the existence of hydroxyls, ether bonds and epoxy groups. In conclusion, the improvement in surface properties was ascribed to the enrichment of epoxy resin moiety on the surface of the nanostructured thermosets.

GuA6DT, a regiospecific prenyltransferase from Glycyrrhiza uralensis, catalyzes the 6-prenylation of flavones.

GuA6DT, a flavonoid prenyltransferase, was identified from Glycyrrhiza uralensis, and it was found that this enzyme regiospecifically transfers a dimethylallyl moiety to apigenin at the C-6 position. A further substrate specificity investigation indicated that the existence of hydroxyls at both the C-5 and C-7 positions of the flavone skeleton is critical for the prenylation. However, substitutions on the B-ring had negligible influence on the prenylation. A comparison of GuA6DT expression in different organs revealed that mRNA is mainly expressed in the aerial parts. Moreover, the GuA6DT mRNA was found to be regulated at the transcriptional level, because methyl jasmonate induced upregulation in cultured cells. GuA6DT is the first identified flavone prenyltransferase to exhibit strict substrate specificity and regiospecificity.

Effect of Annealing on Microstructure of Hydroxyapatite Coatings and their Behaviours in Simulated Body Fluid

In this study, hydroxyapatite (HA) coatings on Ti6Al4V substrate were deposited using an ion beam sputtering technique. Owing to its medical applications, the crystalline phases present in the HA must be controlled. This study investigated the effect of post-deposition heat treatment at different temperatures and evaluated the microstructure of the HA coatings and their behaviours in simulated body fluid (SBF). The post-deposition treatment of the as-deposited samples was carried out in an air-circulated furnace at a temperature between 300 0C and 600 0C. The XRD patterns reveal that the minimum temperature to transform the HA coating from amorphous to crystalline phase is 400 0C. A higher temperature at 600 0C leads to a growth of the crystalline HA phases. Fourier transform infrared spectroscopy (FTIR) measurements show the existence of hydroxyl and PO-bonds in all coatings and the amounts varied with temperature. Atomic Force Microscopy (AFM) study suggests that the nanostructured crystalline HA starts to grow at 400 0C and becomes more obvious at a higher temperature of 600 0C. The simulated body fluid (SBF) test reveals that better apatite formation with post deposition heat treatment at 600 0C would potentially enhance the formation of new bone (osseointegration).

Lupane-type Triterpenoids from the Leaves of Heteropanax fragrans

Lupane-type triterpenoids, a very large and interesting family of compounds, are widely distributed in food, herbs, and other plants throughout the world. This class of compounds possess a wide range of biological properties including cytotoxic, antitumor, antiviral, anti-inflammatory effects and the ability to induce apoptosis in the most prevalent cancer cell lines, such as HepG2, Hep3B and MCF7 cells. The betulinic acid, one of the known lupanetype triterpenoids, showed the selective cytotoxic activity toward melanoma cell lines and is being examined in Phase I trials as a cancer chemoprevention agent. For their various pharmacological and medicinal properties, these pentacyclic triterpenes of the lupane-type have recently been investigated by the scientific community. Heteropanax fragrans (Roxb.) Seem (Araliaceae), an ornamental plant and important source of herb, is distributed in the southern China. The rhizomes of H. fragrans have been used for acesodyne, hemostasia and detumescence by local people. Previous studies reported that four lupane-type triterpenoids and glycosides were isolated from the rhizomes of H. fragrans. However, chemical constituents of the leaves of H. fragrans have not been studied. In this paper, we report the isolation and structure elucidation of one new lupanetype triterpenoid, 3β-hydroxylup-20(29)-ene-23,27,28-trioic acid (1), as well as four known lupane-type derivatives, melaleucic acid (2), 3-oxolup-20(29)-ene-27,28-dioic acid (3), cylicodiscic acid (4), and 3β,23-dihydroxylup-20(29)ene-27,28-dioic acid (5) from the leaves of the title plant (Fig. 1). All the compounds were tested for the cytotoxic activity against KB cell. Compound 1 was obtained as a white amorphous powder. Its molecular formula was assigned as C30H44O7 based on HRESIMS ([M-H]−, m/z 515.2996), C NMR and DEPT data, indicating nine degrees of unsaturation. The IR spectrum of 1 indicated the existence of hydroxyl (3399 cm) and carboxyl groups (1696 cm). Analysis of the H NMR data (Table 1) and the correlations observed in the HSQC experiment showed that the molecule contained four methyl singlets [δH 0.97 (3H, s), 1.18 (3H, s), 1.62 (3H, s), 1.96 (3H,

Observation and quantification of OH radicals in the far downstream part of an atmospheric microwave plasma jet using cavity ringdown spectroscopy

An atmospheric argon microwave plasma jet with a plasma column 8 mm long and 1–2 mm wide is studied. Existence of hydroxyl (OH) radicals down to 28 mm away from the plasma orifice is evidenced by UV cavity ringdown spectroscopy. The measured OH (v″=0, J″=3.5) number density at 28 mm is 7.2×1012 molecule/cm3. The plasma gas flow velocity, along with the known OH lifetimes, suggests that OH radicals observed in the downstream are not the OH radicals formed in the plasma column but were formed in the downstream.

Preparation of Hydrophilic Polystyrene Microspheres with Casein Molecules on the Surface

In this study, suspension polymerization is described to prepare hydrophilic polystyrene microspheres with casein macromolecules on the surface. In the suspension polymerization, casein w as used as an emulsifier and stabilizer instead of synthetic surfactants. The microspheres had spherical shape and the size distribution was narrow, the average size was about 3.5 µm. The microspheres were characterized with a Fourier transform infrared spectroscopy, revealing the existence of hydroxyl, carboxyl and amino groups. XPS analysis was carried out to study the surface composition, it revealed that the nitrogen concentration was 5.04% on the surface of the particles and it remained almost unchanged after the particles were washed by 2% SDS. The microspheres were confirmed to be hydrophilic due to the casein molecules on the surface.

Bioresorbable composite bone paste using polysaccharide based nano hydroxyapatite

Aim of this study concerns to the development of bioresorbable composite materials for bone repair and regeneration. Despite nano hydroxyapatite (HA) has wide range of medical applications, particles mobilization and slow resorbable nature limits its use in certain applications particularly, periodontal and alveolar ridge augmentation. To enhance its usage, we have prepared HA composite bone paste with a natural polysaccharide, chitosan, using wet chemical method at low temperature. The prepared composites were analyzed by various physicochemical methods and suggesting that the nano HA crystallites are well intact with the chitosan macromolecules. FT-IR results are indicating the existence of hydroxyl and amide groups in addition to the characteristic peaks of nano HA in the composite paste. The physical nature of paste form implies that it would be highly beneficial for the particle immobilization upon implantation. In vitro physiological stability and solubility of the composite was performed in phosphate buffered saline under physiological condition and found that the rate of resorbability of composite was quite higher than nano HA. These findings suggest that the HA/chitosan composites may have a great impact on human health care systems as bioresorbable bone substitute.