Thermal degradation kinetics of chitosan–cobalt complex as studied by thermogravimetric analysis

High-efficiency application of CTS-Co NPs mimicking peroxidase enzyme on TMB(ox)

In this study, analytical studies of Chitosan-Cobalt(II) (CTS-Co(II)) nanoparticles (CTS - Co NPs) by mimicking horseradish peroxidase (HRP) were evaluated. In the applications, it was observed that CTS-Co NPs 3,3' 5,5' tetramethylbenzidine (TMB) oxidized in the presence of hydrogen peroxide (H₂O₂). The required CTS-Co NPs were synthesized at 50 °C in 30 min and characterized using Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and X-ray photon spectroscopy (XPS) was done. CTS-Co NPs were studied to develop a selective TMB biosensor on TMB(ox) substrate. The synthesized CTS-Co NPs formed a catalytic reaction with 30% 0.2 mM H₂O₂ on 0.2 M TMB substrate. After the catalytic reaction, sensitive signals were obtained from the desired biosensor. Electrochemical measurements were taken as low limit of 10 mg and a high limit of 20 mg for the determination of CTS-Co NPs to TMB(ox). In the microplate study; The sensors were applied on 1.5 μg and 3 μg CTS-Co NPs TMB(ox) substrate, respectively. CTS- Co NPs; for TMB(ox) determination, optical density (OD) measurement was taken as a low limit of 1.5 μg and a high limit of 3 μg. Electrochemical applications of particles and microplate reader results were compared with horseradish peroxidase (HRP) enzyme for sensor properties. According to the data obtained, it was observed that it behaved similarly to the CTS-Co NPs peroxidase enzyme. This work presents innovations for nanoparticle extraction and sensor study from chitosan and other naturally sourced polymers.

Hemostatic dressings based on poly(vinyl formal) sponges

The development of novel hemostatic agents is related to the fact that severe blood loss due to hemorrhage continues to be the leading cause of preventable death of patients with military trauma and the second leading cause of death of civilian patients with injuries. Herein we assessed the hemostatic properties of porous sponges based on biocompatible hydrophilic polymer, poly(vinyl formal) (PVF), which meets the main requirements for the development of hemostatic materials. A series of composite hemostatic materials based on PVF sponges with different porosities and fillers were synthesized by acetalization of poly(vinyl alcohol) with formaldehyde. Nano-sized aminopropyl silica, micro-sized calcium carbonate, and chitosan hydrogel were used to modify PVF matrixes. The physicochemical properties (pore size, elemental composition, functional groups, hydrophilicity, and acetalization degree) of the synthesized composite sponges were studied by gravimetrical analysis, optical microscopy, scanning electron microscopy combined with energy dispersive x-ray spectroscopy, infrared spectroscopy, and nuclear magnetic resonance. Hemostatic properties of the materials were assessed using a model of parenchymal bleeding from the liver of white male Wistar rat with a gauze bandage as a control. All investigated PVF-based porous sponges showed high hemostatic activity: upon the application of PVF-samples the bleeding decreased within 3 min by 68.4-94.4% (р < 0.001). The bleeding time upon the application of PVF-based composites decreased by 78.3-90.4% (p < 0.001) compared to the application of well-known commercial product Celox™.

A novel chitosan-vanadium-titanium-magnetite composite as a superior adsorbent for organic dyes in wastewater

In this research, a novel chitosan (CS)-vanadium-titanium-magnetite (VTM) composite was designed and synthesized. The interaction between CS-VTM and Congo red (CR) dye conformed to a pseudo-second-order model to support the potent involvement of chemisorption. The effects of adsorbent dosage, reaction temperature, and initial solution pH on adsorption of CR were investigated. Approximately 99.1% of CR (100 mg/L) was adsorbed at a CS-VTM dose of 2.0 g/L or above, while such a reaction was favored at temperatures of 65 °C and pH of 6.0. Thermodynamically, the adsorption of CR proceeded spontaneously (ΔG < 0) above 35 °C. According to scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectrometer, and zeta potential analysis, its adsorption on CS-VTM can be attributed to electrostatic attraction and hydrogen bonds. The prepared CS-VTM exhibited superior adsorption performance on removal of CR as evidenced by significantly large partition coefficient of 108.3 mg g^-1 μM^-1 (equilibrium adsorption capacity of 62.2 mg/g at CR dose of 100 mg/L). Overall, the CS-VTM proved to be a promising and environmentally friendly adsorbent for the highly efficient and effective removal of organic dyes among the comparable sorbents studied to date.

Characterization and Dimethyl Phthalate Flocculation Performance of the Cationic Polyacrylamide Flocculant P(AM-DMDAAC) Produced by Microwave-Assisted Synthesis

A composite flocculant P(AM-DMDAAC) was synthesized by the copolymerization of acrylamide (AM) and dimethyl diallyl ammonium chloride (DMDAAC). By using microwave (MV) assistance with ammonium persulfate as initiator, the synthesis had a short reaction time and yielded a product with good solubility. Fourier-transform infrared spectroscopy, scanning electron microscopy, and differential thermal analysis-thermogravimetric analysis were employed to determine the structure and morphology of P(AM-DMDAAC). The parameters affecting the intrinsic viscosity of P(AM-DMDAAC), such as MV time, mass ratio of DMDAAC to AM, bath time, reaction temperature, pH value, and the dosages of ammonium persulfate initiator, EDTA, sodium benzoate, and urea were examined. Results showed that the optimum synthesis conditions were MV time of 1.5 min, m(DMDAAC):m(AM) of 4:16, 0.5 wt‱ initiator, 0.4 wt‱ EDTA, 0.3 wt‱ sodium benzoate, 2 wt‱ urea, 4 h bath time, reaction temperature of 40 °C, and pH of 2. The optimal dimethyl phthalate (DMP) removal rate can reach 96.9% by using P(AM-DMDAAC), and the P(AM-DMDAAC) had better flocculation than PAM, PAC, and PFS.

Chitosan-Glycerol Gel as Barrier Formulation for Metal Allergy

Metal-induced allergic contact dermatitis, particularly nickel, affects over 10% of the general population. Herein, chitosan-glycerol gel as protective barrier formulation was synthesized by neutralization reaction with an aim to reduce metal-ion diffusion into the skin to prevent allergy. Active functional groups in chitosan-glycerol gel were able to capture allergenic metal ions present in artificial sweat solution. The efficacy of the barrier formulation against nickel-ion penetration was evaluated ex vivo using pig skin. We found that the percutaneous absorption of nickel ion reduced by ∼98% when chitosan-glycerol gel was used as a barrier formulation.

Using ultrasonic (US)-initiated template copolymerization for preparation of an enhanced cationic polyacrylamide (CPAM) and its application in sludge dewatering

In this study, the ultrasonic (US)-initiated template copolymerization was employed to synthesize a novel cationic polyacrylamide (CPAM) characterized by a microblock structure using dimethyldiallylammonium chloride (DMDAAC) and acrylamide (AM) as monomers, and sodium polyacrylate (NaPAA) as template. The polymers structure property was analyzed by Fourier transform infrared spectroscopy (FT-IR), ¹H nuclear magnetic resonance spectroscopy (¹H NMR) and thermogravimetric analysis (TGA). The results showed that a novel cationic microblock structure was successfully synthesized in the template copolymer of DMDAAC and AM (TPADM). Meanwhile, the analysis result of association constant (M_K) provided powerful support for a I Zip-up (ZIP) template polymerization mechanism and the formation of the microblock structure. The factors affecting the polymerization were investigated, including ultrasonic power, ultrasonic time, monomer concentration, initiator concentration, m_AM:m_DMDAAC and n_NaPAA:n_DMDAAC. The sludge dewatering performance of the polymers was evaluated in terms of specific resistance to filtration (SRF), filter cake moisture content (FCMC), floc size (d₅₀) and fractal dimension (D_f). Flocculation mechanism was also analyzed and discussed. The sludge dewatering results revealed that the polymer with the novel microblock structure showed a more excellent flocculation performance than those with randomly distributed cationic units. A desirable flocculation performance with a SRF of 4.5 × 10¹² m kg^-1, FCMC of 73.1%, d₅₀ of 439.156 µm and D_f of 1.490 were obtained at pH of 7.0, dosage of 40 mg L^-1 and the molecular weight of 5.0 × 10⁶ Da. The cationic microblock extremely enhanced the polymer charge neutralization and bridging ability, thus obtaining the excellent sludge dewatering performance.

Size optimization and in vitro biocompatibility studies of chitosan nanoparticles

Chitosan (CS), an amino polysaccharide has fascinating scientific applications due to its many flexible properties. The advantages of Chitosan tend to increase when it was modified. Thus, in the present research work, to improve the properties of chitosan, it was converted into chitosan nanoparticles (CS-NPs) through the ionic gelation method using sodium tripoyphosphate (TPP) and sodium hexametaphosphate (SHMP) as a crosslinker. The size optimization was done by varying the parameters such as crosslinker concentration, agitation method and rate, agitation time, temperature and drying method. The prepared samples were characterized using FTIR, TGA, XRD, SEM, TEM and DLS. Also the prepared CS-NPs with TPP and SHMP had been evaluated in vitro for determining its hemocompatibility, biodegradability, serum stability, cytotoxicity and cell viability. The results showed the significant participation of all the parameters in obtaining the nanoparticles in 20-30nm and 5-10nm for CS-NPs-TPP air dried and freeze dried samples and around 60-80nm and 20-30nm for CS-NPs-SHMP air dried and freeze dried samples. The in vitro biological studies revealed that the nanoparticles are non-toxic with a good degree of biodegradability, blood compatibility and stability.

Fabrication of letrozole formulation using chitosan nanoparticles through ionic gelation method

In this study, the anticancer drug letrozole (LTZ) was formulated using chitosan nanoparticles (CS-NPs) with the crosslinking agent sodium tripolyphosphate (TPP). The nano-formulation was optimized by varying the concentration of drug. The prepared particles were characterized using FTIR, TGA, XRD, SEM, TEM and DLS. From the FTIR results, the appearance of a new peak for CH, CC and CN confirms the formation of LTZ loaded chitosan nanoparticles. TEM images shows that the average particle size was in the range of 60-80nm and 20-40mm air dried and freeze dried samples respectively. Also the prepared formulation had been evaluated in vitro for determining its hemocompatability, biodegradability and serum stability. The preliminary studies supported that the chitosan nanoparticles formulation has biocompatibility and hemocompatible properties and it can act as an effective pharmaceutical excipient for letrozole.

Enhancement of textile-dyeing sludge dewaterability using a novel cationic polyacrylamide: role of cationic block structures

A novel cationic polyacrylamide (CPAM) with a microblock structure was synthesized through ultrasonic-initiated template copolymerization (UTP) using allyltrimethylammonium chloride (TM) and acrylamide (AM) as monomers, and sodium polyacrylate (NaPAA) as a template.

Theoretical and analyzed data related to thermal degradation kinetics of poly (L-lactic acid)/chitosan-grafted-oligo L-lactic acid (PLA/CH-g-OLLA) bionanocomposite films

The theoretical and analyzed data incorporated in this article are related to the recently published research article entitled “Thermal degradation behaviour of nanoamphiphilic chitosan dispersed poly (lactic acid) bionanocomposite films” (http://dx.doi.org/10.1016/j.ijbiomac.2016.11.024) (A.K. Pal, V. Katiyar, 2016) [1]. Supplementary information and data (both raw and analyzed) are related to thermal degradation kinetics and explains various model fitting and is conversional methods, which are used in this research work to enhance the knowledge about degradation behaviour of PLA/CH-g-OLLA bionanocomposite system. Non-isothermal degradation kinetics of such polymeric system was proposed using Kissinger, Kissinger–Akahira–Sunose, Flynn–Wall–Ozawa and Augis and Bennett models to estimate the activation energies (E_a) and R² values.