Hydroxypropyltrimethyl Ammonium Chloride Chitosan Research Articles

Spatially-controlled distribution of HACC in mineralized collagen coatings for improving rhBMP-2 loading and release behavior

In this study, mineralized collagen (COL) coatings with controlled loading and release of bone morphogenetic protein (rhBMP-2) as well as enhanced osteogenic differentiation were successfully achieved via the spatially-control of hydroxypropyltrimethyl ammonium chloride chitosan (HACC) within the coatings. The distribution of HACC in the inner part (HACC-IN) or the outer part (HACC-OUT) of the coatings were adjusted by different potential values and negative/positive alternations during alternating potentials assisted electrochemical deposition (AP-ECD). It was found that rhBMP-2 loading capacity was remarkably enhanced with the increased incorporation of HACC due to their strong interaction, and the release behavior was also tuned by HACC location. In general, HACC-IN coatings showed a prominent improvement in cytocompatibility and osteogenic differentiation. The main reason is considered that the inner location of HACC can eliminate the negative effect of HACC to initial cellular adhesion and bring to a sustained rhBMP-2 release behavior due to kinetic modification. An optimized coating in this work could load as high as 4644ng/cm2 rhBMP-2 and release only 25% for 14 days, which consequently leads to a better osteogenic differentiation. This study has thus inspired another promising protocol for designing growth factor incorporated bioactive coatings for bone implants with improved osteointegration.

Inhibited Bacterial Adhesion and Biofilm Formation on Quaternized Chitosan-Loaded Titania Nanotubes with Various Diameters.

Titania nanotube-based local drug delivery is an attractive strategy for combating implant-associated infection. In our previous study, we demonstrated that the gentamicin-loaded nanotubes could dramatically inhibit bacterial adhesion and biofilm formation on implant surfaces. Considering the overuse of antibiotics may lead to the evolution of antibiotic-resistant bacteria, we synthesized a new quaternized chitosan derivative (hydroxypropyltrimethyl ammonium chloride chitosan, HACC) with a 27% degree of substitution (DS; referred to as 27% HACC) that had a strong antibacterial activity and simultaneously good biocompatibility with osteogenic cells. Titania nanotubes with various diameters (80, 120, 160, and 200 nm) and 200 nm length were loaded with 2 mg of HACC using a lyophilization method and vacuum drying. Two standard strain, methicillin-resistant Staphylococcus aureus (American Type Culture Collection 43300) and Staphylococcus epidermidis (American Type Culture Collection 35984), and two clinical isolates, S. aureus 376 and S. epidermidis 389, were selected to investigate the bacterial adhesion at 6 h and biofilm formation at 24, 48, and 72 h on the HACC-loaded nanotubes (NT-H) using the spread plate method, confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM). Smooth titanium (Smooth Ti) was also investigated and compared. We found that NT-H could significantly inhibit bacterial adhesion and biofilm formation on its surface compared with Smooth Ti, and the NT-H with 160 nm and 200 nm diameters had stronger antibacterial activity because of the extended HACC release time of NT-H with larger diameters. Therefore, NT-H can significantly improve the antibacterial ability of orthopedic implants and provide a promising strategy to prevent implant-associated infections.

Synthesis, Characterization and Inhibition Performance of Vanillin‐Modified Chitosan Quaternary Ammonium Salts for Q235 Steel Corrosion in HCl Solution

AbstractIn order to enhance the solubility of chitosan in water and its corrosion inhibition performance on Q235 steel in 1 M HCl solution, N‐vanillyl‐O‐2′‐hydroxypropyltrimethylammonium chloride chitosan (VHTC) was synthesized. The structure of VHTC was characterized by FT‐IR and 1H‐NMR spectroscopy. The corrosion inhibition performance of VHTC on Q235 steel in 1 M HCl solution was studied by weight loss, polarization, electrochemical impedance spectroscopy (EIS) and stereo microscope analysis. Experimental results indicate that VHTC shows better inhibition efficiency compared to chitosan. When the concentration of VHTC increases to 200 mg L−1, the inhibition efficiency reaches 90 %, which is almost equal to the conventional corrosion inhibitors (e.g., imidazoline). The polarization study demonstrates that VHTC is a mixed‐type inhibitor caused by a geometrical blanketing effect. The charge transfer resistance is proportional to the inhibitor concentration as revealed by the EIS results, indicating that the protective film on the Q235 steel surface is formed by adsorption of the inhibitor molecules. The inhibition efficiency of VHTC achieves the maximum value within 24 h when the concentration of VHTC is 200 mg L−1. The morphology observation of the corroded steel surface indicates that the corrosion of Q235 steel in 1 M HCl solution is significantly inhibited after introducing VHTC into the acidic solution.

O-2′-Hydroxypropyltrimethyl ammonium chloride chitosan nanoparticles for the delivery of live Newcastle disease vaccine

A novel complex chitosan derivative, O-2′-hydroxypropyltrimethyl ammonium chloride chitosan (O-2′-HACC), was synthesized and used to make nanoparticles as a delivery vehicle for live attenuated Newcastle disease vaccine. We found that O-2′-HACC had high antimicrobial activity, low toxicity, and a high safety level. Newcastle disease virus (NDV) was then encapsulated in the O-2′-HACC nanoparticles (NDV/La Sota-O-2′-HACC-NPs) by the ionic crosslinking method, and the properties of the resulting nanoparticles were determined by transmission electron microscopy, Zeta potential analysis, Fourier transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and X-ray diffraction. NDV/La Sota-O-2′-HACC-NPs had regular spherical morphologies and high stability, with an encapsulation efficiency of 95.68±2.2% and a loading capacity of 58.75±4.03%. An in vitro release assay indicated that release of NDV from NDV/La Sota-O-2′-HACC-NPs occurred slowly. Specific pathogen-free chickens immunized with NDV/La Sota-O-2′-HACC-NPs intranasally had much stronger cellular, humoral and mucosal immune responses than did those immunized intramuscularly or with live attenuated Newcastle disease vaccine. NDV/La Sota-O-2′-HACC-NPs are a novel drug delivery carrier with immense potential in medical applications.

Quaternary ammonium salt of chitosan: preparation and antimicrobial property for paper.

A series of 2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC) was prepared by the reaction of chitosan with glycidyl trimethyl ammonium chloride. Structure of HACC was characterized by FT IR and 1H NMR spectroscopies, and it was proved that substitution reaction mainly occurs on the N element. Antimicrobial activities of HACC was examined against S. aureus, E. coli, and A. niger. Results indicatd that the inhibitory effects of HACC solutions were varied with HACC concentration, quaternization degrees, pH values, metal ions, and heat treatment. The antimicrobial properties of handsheets prepared from HACC were studied by the inhibition zone method, and the sheets had good antimicrobial properties against S. aureus and E. coli, and low inhibition rate against A. niger.

Enhanced bone tissue regeneration by antibacterial and osteoinductive silica-HACC-zein composite scaffolds loaded with rhBMP-2

Next-generation orthopedic implants with both osteoinductivity and antibacterial ability are greatly needed. In the present study, biodegradable rhBMP-2 loaded zein-based scaffolds with a macroporous structure were synthesized, and SBA-15 nanoparticles and hydroxypropyltrimethyl ammonium chloride chitosan (HACC) were incorporated into the scaffolds to produce an anti-infective composite scaffold for delivery of osteogenic factors that facilitate the functional repair of bone defects. The silica/HACC/zein scaffolds developed here showed bioactivity, biocompatibility, and effective antibacterial activity. Confocal laser scanning microscopy (CLSM) was used to quantitatively measure the bactericidal efficacy with respect to bacterial adhesion. Results showed that the sample zein-HACC-S20 exhibited long-lasting antibacterial activity against Escherichia coli and Staphylococcus aureus up to 5 d. At a low dosage of rhBMP-2 (ca. 80 μg), the scaffolds released rhBMP-2 protein efficiently at a relatively slow rate, even after 27 d. An ALP activity and ECM mineralization assay showed that the zein-HACC-S20 scaffolds exhibited significant early osteogenic differentiation by generating enhanced ALP product on day 14 and ECM mineralization on day 21. In a mouse model of thigh muscle pouches, zein-S20 and zein-HACC-S20 groups resulted in obvious bone formation and gave more extensive mineralization to the implants than silica free groups, indicating effective bone induction in vivo. In a rabbit model of critical-sized radius bone defects (20 mm in length and 5 mm in diameter), the bone defects were almost fully repaired and bone marrow cavity recanalization was detectable by 3D micro-CT technique and histological analysis after 12 weeks. In this way, the zein-HACC-S20 scaffolds were proven to significantly promote the bone repair. They also demonstrated considerable promise for tissue engineering. Silica/HACC/zein scaffolds with both antibacterial activity and the ability to induce osteogenesis have immense potential in orthopedics and other biomedical applications.

In vivo effect of quaternized chitosan-loaded polymethylmethacrylate bone cement on methicillin-resistant Staphylococcus epidermidis infection of the tibial metaphysis in a rabbit model.

Infection of open tibial fractures with contamination remains a challenge for orthopedic surgeons. Local use of antibiotic-impregnated polymethylmethacrylate (PMMA) beads and blocks is a widely used procedure to reduce the risk of infection. However, the development of antibiotic-resistant organisms make the management of infection more difficult. Our in vitro study demonstrated that quaternized chitosan (hydroxypropyltrimethyl ammonium chloride chitosan [HACC])-loaded PMMA bone cement exhibits strong antibacterial activity toward antibiotic-resistant bacteria. Therefore, the present study aimed to investigate the in vivo antibacterial activity of quaternized chitosan-loaded PMMA. Twenty-four adult female New Zealand White rabbits were used in this study. The right proximal tibial metaphyseal cavity was prepared, 10(7) CFU of methicillin-resistant Staphylococcus epidermidis was inoculated, and PMMA-only, gentamicin-loaded PMMA (PMMA-G), chitosan-loaded PMMA (PMMA-C), or HACC-loaded PMMA (PMMA-H) bone cement cylinders were inserted. During the follow-up period, the infections were evaluated using X rays on days 21 and 42 and histopathological and microbiological analyses on day 42 after surgery. Radiographic indications of bone infections, including bone lysis, periosteal reactions, cyst formation, and sequestral bone formation, were evident in the PMMA, PMMA-G, and PMMA-C groups but not in the PMMA-H group. The radiographic scores and gross bone pathological and histopathological scores were significantly lower in the PMMA-H group than in the PMMA, PMMA-G, and PMMA-C groups (P < 0.05). Explant cultures also indicated significantly less bacterial growth in the PMMA-H group than in the PMMA, PMMA-G, and PMMA-C groups (P < 0.01). We concluded that PMMA-H bone cement can inhibit the development of bone infections in this animal model inoculated with antibiotic-resistant bacteria, thereby demonstrating its potential application for treatment of local infections in open fractures.

Thermal degradation of hydroxypropyl trimethyl ammonium chloride chitosan–Cd complexes

Thermal degradation of hydroxypropyl trimethyl ammonium chloride chitosan–Cd complexes (HTCC–Cd) was investigated by thermogravimetric analysis. The results indicate that the degradation of HTCC–Cd in nitrogen atmosphere was two-step reaction. For the first step of degradation, the initial temperature of mass loss (T 0), the final temperature of mass loss (T f), and the temperature of maximum mass loss (T p) increase linearly with the rising of heating rate (B). T o = 1.241B + 220.3, T p = 1.111B + 245.8, and T f = 1.335B + 358.2. Using different methods, the kinetic parameters of the two steps were investigated. The results show that the activation energies of the first step of degradation obtained using Friedman and Flynn–Wall–Ozawa methods are 1.684 × 105 and 1.646 × 105 J mol−1, and the corresponding activation energies for the second step are 1.165 × 105 J mol−1 and 1.373 × 105 kJ mol−1. The results obtained from Phadnis–Deshpande methods indicate that the two degradation processes are both nucleation and growth process, and follow A4 mechanism with intergral form g(X) = [−ln(1 − X)]4.

Evaluation of antibacterial activity of N-phosphonium chitosan as a novel polymeric antibacterial agent

N-phosphonium chitosans (NPCSs) with different degrees of substitution (3%, 13% and 21%) were synthesized and evaluated as novel polymeric antibacterial agents. Their antibacterial activities compared with hydroxypropyltrimethyl ammonium chloride chitosan (HACC), parent chitosan and (5-carboxypentyl) triphenylphosphonium bromide (CTPB) were tested against Escherichia coli and two strains of drug-resistance Staphylococcus aureus by minimal inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and biofilm prevention assays. The results show that the NPCS with 3% or 13% substitution has lower MIC and MBC values and stronger ability to inhibit biofilm formation of all the three bacteria than HACC, chitosan and CTPB. In addition, the antibacterial activity of NPCSs increases with their substitution decreasing from 21% to 3%. Overall, the antibacterial activity of NPCS with 3% or 13% substitution is better than that of NPCS with 21% substitution, HACC with 22% substitution, chitosan and CTPB. It can be considered that NPCS with appropriate degree of substitution has favorable antibacterial activity and is a potential polymeric antibacterial agent.

New multilayer coating using quaternary ammonium chitosan and κ-carrageenan in capillary electrophoresis: application in fast analysis of betaine and methionine.

The aim of this study was to develop a new multilayer coating with crosslinked quaternary ammonium chitosan (hydroxypropyltrimethyl ammonium chloride chitosan; HACC) and κ-carrageenan for use in capillary electrophoresis. A new semi-permanent multilayer coating was formed using the procedure developed and the method does not require the presence of polymers in the background electrolyte (BGE). The new capillary multilayer coating showed a cathodic electroosmotic flow (EOF) of around 30×10(-9) m(2) V(-1) s(-1) which is pH-independent in the range of pH 2 to 10. The enhanced EOF at low pH obtained contributed significantly to the development of a fast method of separation. The multilayer coating was then applied in the development of a fast separation method to determine betaine and methionine in pharmaceutical formulations by capillary zone electrophoresis (CZE). The BGE used to determine the betaine and methionine concentrations was composed of 10 mmol L(-1) tris(hydroxymethyl) aminomethane, 40 mmol L(-1) phosphoric acid and 10% (v/v) ethanol, at pH 2.1. A fused-silica capillary of 32 cm (50 µm ID×375 µm OD) was used in the experiments and samples and standards were analyzed employing the short-end injection procedure (8.5 cm effective length). The instrumental analysis time of the optimized method was 1.53 min (approx. 39 runs per hour). The validation of the proposed method for the determination of betaine and methionine showed good linearity (R(2)>0.999), adequate limit of detection (LOD <8 mg L(-1)) for the concentration in the samples and inter-day precision values lower than 3.5% (peak area and time migration). The results for the quantification of the amino acids in the samples determined by the CZE-UV method developed were statistically equal to those obtained with the comparative LC-MS/MS method according to the paired t-test with a confidence level of 95%.

Quaternised chitosan-loaded polymethylmethacrylate bone cement: Biomechanical and histological evaluations

Our previous studies have demonstrated that the quaternised chitosan-loaded polymethylmethacrylate (PMMA) is a promising new antibacterial bone cement. The aim of this study was to evaluate biomechanical properties of quaternised chitosan-loaded PMMA in vitro and interface histology between cement and bone in vivo. In this study, hydroxypropyltrimethyl ammonium chloride chitosan (HACC) with 26% degree of substitution (referred to as 26% HACC) was loaded into PMMA bone cement at a 20% mass ratio, and the specimens of 26% HACC-loaded PMMA bone cement (PMMA–H) were prepared for compressive and bending mechanical test according to ISO 5883-2002 standard prior to and after the 4-week immersion in PBS. The chitosan-loaded PMMA bone cement (PMMA–C) at the same mass ratio, pure PMMA, and gentamicin-loaded PMMA (PMMA–G) were also prepared and tested as controls. Then each of four kinds of bone cements was implanted into the rabbit femoral condyle and the osseointegration of the cement–bone interface was evaluated after its implantation over 6 weeks. The results show that biomechanical properties of both PMMA–C and PMMA–H were reduced significantly compared with the PMMA or PMMA–C, and the elastic modulus of PMMA–H was close to that of human cancellous bone. Histological observation in animal studies indicates that there was better osseointegration at the cement–bone interface in the PMMA–H group than that in the PMMA, PMMA–G, or PMMA–C groups. More new bone formation was found around PMMA–H bone cement as compared with that in the other three groups. Our findings indicated that the biomechanical properties of PMMA–H were reduced but close to that of neighbouring bone. The PMMA–H had good biocompatibility and osseointegration potential, implying its suitability for vertebral augmentation of osteoporotic vertebral compression fractures and fixation of prosthesis in cemented joint replacement.

Flocculation of Quaternary Chitosan on Acid Dyeing Waste Water

In order to increase the positively charge, solubility in water and grafted degree of chitosan, quaternary chitosan was synthesized with chitosan and glycidyl-trimethyl-ammonium chloride by the heterogeneous reaction. FT-IR was used to characterize the structure of the synthesized. The quaternary chitosan was then used to treat simulated acid dyeing wastewater, the effect of quaternary chitosan concentration, agitation mode and pH values on flocculation were discussed. The results indicated that the H+ in nucleophilic center-NH2 was displaced by-CH2CH(OH)CH2N+(CH3)3 and the 2-hydroxypropyltrimethyl ammonium chloride chitosan (quaternary chitosan) was synthesized. When applied to treatment of acid dye waste water, the decolorization rate was 95.5%, and the COD removal was 86.4%.

Preparation and application of positively charged quaternized chitosan/PEI composite nanofiltration membranes

Membrane processes are gaining importance in water applications as a result of the advances in membrane technology and the increasing requirements on water quality. In this work, 2-hydroxypropyltrimethyl ammonium chloride chitosan with positively charged character and good membrane-forming ability was utilized to fabricate the functional layer of the composite nanofiltration (NF) membrane. Reinforced polyetherimide ultrafiltration membrane was used as the support layer for its excellent thermal and solvent resistance. Effects of polymer concentration, reaction time, cross-linking agent concentration, and cross-linking temperature on membrane performance were studied in detail. When the composite membrane was prepared under optimized conditions and tested at 0.3 MPa and 20°C, the flux of the composite NF membrane was about 10.9 L/m2h and the MgCl2 rejection of it was about 83.1%. The surface morphologies of the composite membrane and substrate membrane were observed by scanning electron microscopy. The composite membrane showed a classical positively charged membrane character which had higher rejection to multivalent cations.

Preparation and Characterization of Positively Charged Quaternized Chitosan/PEI Composite Nanofiltration Membranes

2-Hydroxypropyltrimethyl ammonium chloride chitosan (HACC) with positively charged character was utilized to fabricate the functional layer of the composite NF membrane and reinforced polyetherimide (PEI) ultrafiltration (UF) membrane was used as the support layer. When the composite membrane was prepared under optimized conditions and tested at 0.4 MPa and 10 oC, the flux of the composite NF membrane was about 18 L/m2h and the MgCl2 rejection of it was about 81.6%. The composite membrane showed classical positively charged membrane character which had higher rejection to high valent inorganic salts.

Synthesis, in vitro and in vivo evaluation of new norcantharidin-conjugated hydroxypropyltrimethyl ammonium chloride chitosan derivatives as polymer therapeutics

New norcantharidin-conjugated hydroxypropyltrimethyl ammonium chloride chitosan derivatives (NCTD-HACCs) were synthesized and characterized by (1)H NMR, Fourier-transform infrared spectroscopy (FT-IR), and wide-angle X-ray diffraction (WAXD). Two NCTD-HACCs with different degrees of substitution (DS) (12.2% and 24.8%) were obtained, which had good water solubility. NCTD was released from the NCTD-HACCs via hydrolysis, faster in pH 5.0 than pH 7.4 and presenting one biphasic drug release pattern with rapid release at the initial stage and slow release later. Fluorescence microscope and flow cytometry analysis demonstrated that the NCTD-HACC was endocytosized into MGC80-3 cells and the uptaken amount increased as incubation time. Compared with free NCTD, the NCTD-HACCs showed lower in vitro anti-tumor activity against human gastric cancer MGC80-3 cells, but higher in vivo tumor growth inhibition in S180 tumor-bearing mice. The in vivo near-infrared (NIR) fluorescence real-time imaging result showed the fluorescence intensity in tumor was much higher than that in heart, liver, spleen and lung (except kidney) after i.v. injection of the FITC-labeled NCTD-HACC2, indicating specific accumulation of the NCTD-HACC in tumor.

A new antibacterial and strength-reinforced calcium phosphate cements

Objective To evaluation the mechanical behavior and the ability of antibacterial of the new calcium phosphate bone cement (CPC).Methods The CPC was reinforced by chitosan fiber with hydroxypropyltrimethyl ammonium chloride chitosan (HACC).The spread plate analysis and confocal laser scanning microscopy were used for bacterial adherence assay.The strength of the samples was investigated by a standard three-point bending test.Cell toxicity and proliferation of cells were also invested.Results The new bone cement showed a good antibacterial activity which had the least amount of surviving bacterial as (0.10 ± 0.09) ％.The results of three-point bending test also showed the incorporation of chitosan fiber [(17.3 ± 4.5) MPa and (16.9 ± 3.9) MPa] significantly increased the mechanical strength of CPC [(5.3 ± 1.4) MPa].And the reinforcement has no harmful to the biocompatibility of CPC.Extracts of new bone cement showed non-cytotoxic (97.5 ± 3.3)％.The methyl thiazol tetrazolium (MTT) activity of cells is 0.237 ± 0.025,0.503 ± 0.015,0.726 ± 0.032 during 3 days cultured.Conclusion CPC combined with chitosan fiber with HACC can meet the needs of strength,biocompatibility and antibacterial activity. Key words: Calcium phosphate bone cement; Antibacterial; Reinforcement; Chitosan

Antibacterial properties and bioactivity of HACC- and HACC-Zein-modified mesoporous bioactive glass scaffolds.

Infection and its complications are one of the greatest threats to the health of orthopedic patients. Mesoporous bioglass (MBG) scaffolds are characterized by well-ordered, three-dimensional, nanometer-sized mesoporous structures, which facilitate the adhesion of hydroxyapatite and the loading of drugs. MBG has been widely used as a new-generation biomaterial in bone tissue engineering. However, MBG is very brittle and lacks antibacterial activity. This limits its applications in the treatment of bone defects, especially large bone defects complicated by infection. In order to dispel these disadvantages, a novel hydroxypropyltrimethyl ammonium chloride chitosan (HACC) and a class of prolamine proteins found in maize, Zeins, were here used to modify the traditional MBG scaffolds. Two new types of scaffold, MBG-HACC scaffolds and MBG-HACC-Zein scaffolds, were made. Transmission electron microscopy (TEM), small angle X-ray diffraction (SAXRD), and Barrett-Joyner-Halenda (BJH) were used to analyze the surface properties of these MBG scaffolds. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), mechanical experiments, and synchrotron radiation microcomputer tomography (SRμCT) were used to compare the features of the traditional and modified scaffolds and to analyze the mineralization of the scaffold after being soaked in simulated body fluid (SBF). Confocal laser scanning microscopy (CLSM) was used to compare the antibacterial properties and biocompatibility of the scaffolds at various points in time. The current study demonstrates that all these prepared MBG scaffolds possessed well-ordered, three-dimensional, nanometer-sized mesoporous structures and that HACC-Zein-modified MBG scaffolds are characterized by strong bioactivity and by effective, prolonged antibacterial activity. Finally, biocompatibility was demonstrated by studying the in vitro proliferation and viability of human mesenchymal stem cells (hMSCs).

The bactericidal and biocompatible characteristics of reinforced calcium phosphate cements

Infection remains a serious medical problem in orthopaedic surgery. Antibiotic administration can be available either systemically via the blood stream or locally, directly into the infected bone. One of the main limitations of antibiotic administration is the development of multi-antibiotic-resistant bacterial strains. In this study, we developed bactericidal calcium phosphate cements (CPC) by incorporation of different molecular weight chitosan and hydroxypropyltrimethyl ammonium chloride chitosan (HACC). Two standard strains, S. epidermidis (ATCC35984) and S. aureus (ATCC25923), and one clinical isolate, methicillin-resistant S. epidermidis (MRSE), were selected to evaluate the antibacterial activity of these bone cements. Our data showed that the CPC loaded with low molecular weight chitosan and HACC significantly inhibited the bacterial adhesion and biofilm formation. In addition, HACC-containing CPC has no cytotoxic effects on both mouse pluripotent C3H10T1/2cell line and a murine L929 fibroblast cell line. We propose that HACC-containing CPC represents a promising polymer-based bactericidal bone scaffold in controlling orthopaedic surgery-related infection.

Coagulation of Sericin Protein in Silk Degumming Wastewater Using Quaternized Chitosan

The evaluation of 2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC), a biodegradable cationic polymer, for the coagulation of sericin in silk degumming waste solution was carried out using jar-test coagulation experiments. The coagulation efficiency was assessed by the factors of residual turbidity, sericin removal and CODCr. The results indicated that the efficiency were dependent on the operational parameters of pH, coagulant dosage and settling time. The optimal pH value was found to be around 8, while a 1 g/L HACC dosage was sufficient in providing more than 98 % turbidity removal and 76 % sericin removal. The results were comparable to those got by the use of conventional coagulants. The coagulation of sericin by HACC may be involved in a dual mechanism including charge neutralization and bridging mechanism. Moreover, the sludge cake from the coagulation, mainly containing sericin protein and modified chitosan, might be used as finishing agent for polyester fabric or food additive for animals after fundamental purified.

Physical characterization and osteogenic activity of the quaternized chitosan-loaded PMMA bone cement

Gentamicin-loaded polymethylmethacrylate (PMMA), widely used for primary cemented arthroplasty and revision surgery for preventing or treating infections, may lead to the evolution of antibiotic-resistant bacteria and dysfunction of osteogenic cells, which further influence the osteointegration of bone cement. In a previous study, we reported that a new quaternized chitosan derivative (hydroxypropyltrimethyl ammonium chloride chitosan, HACC) that was loaded into PMMA significantly inhibited the formation of biofilms caused by methicillin-resistant Staphylococcus strains. In the present study, we further investigated the surface morphology, hydrophilicity, apatite formation ability and osteogenic activity of HACC-loaded PMMA. Chitosan-loaded PMMA, gentamicin-loaded PMMA and PMMA without antibiotic were also investigated and compared. The results showed that, compared to other PMMA-based cements, HACC-loaded PMMA had improved properties such as a lower polymerization temperature, prolonged setting time, porous structures after immersion in phosphate-buffered saline, higher hydrophilicity, more apatite formation on the surface after immersion in simulated body fluid, and better attachment and spreading of the human-marrow-derived mesenchymal stem cells. We also found better stem cell proliferation, osteogenic differentiation, and osteogenesis-associated genes expression on the surface of the HACC-loaded PMMA compared to the gentamicin-loaded PMMA. Therefore, this new anti-infective bone cement had improved physical properties and osteogenic activity, which may lead to better osteointegration of the bone cement in cemented arthroplasty.