PBS Of pH Research Articles

Development of an inexpensive poly(MO)/CNT@PGE for voltammetric investigation of Methocarbamol in presence of Levofloxacin

This work describes the voltammetric investigation of trace amounts of pain reliever drug methocarbamol (MET) by carbon nanotubes decorated methyl orange polymerized pencil graphite electrode (poly(MO)/CNT@PGE). The proposed modified electrode was prepared by electropolymerization of methyl orange (MO) over the carbon nanotubes (CNTs) decorated on PGE. The geomorphologies of the equipped sensors were accomplished by scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX) and electrochemical impedance spectroscopy (EIS) study. The electrochemical behaviour of MET in presence of levofloxacin (LVF) has been studied by applying different voltammetric techniques in 0.1 M PBS of pH 4.0. The proposed poly(MO)/CNT@PGE shows enhanced peak current with a small negative shift in peak potential for MET over the bare and modified electrodes due to the electrocatalytic features of the modifiers. The different parameters such as effect of polymer layers, pH, scan rate, concentrations, simultaneous and selectivity study for MET were studied by cyclic voltammetry (CV), linear sweep voltammetry (LSV), differential pulse voltammetry (DPV) and square wave voltammetry (SWV). The computed limit of detection (LOD) for MET at different concentrations (10.0–110.0 µM for DPV and 1.0–12.0 µM for SWV) was found to be 5.24 µM and 0.69 µM, respectively. The adapted electrode exhibits special characteristic features such as stability, repeatability, reproducibility, fast electron transfer behaviour and charge transfer resistance (Rct). Based on the results obtained, number of electrons (n), number of protons (m), heterogeneous rate constant (ko) and surface concentration (Γ0) of MET have been calculated by using relative formulae. The selectivity and applicability of the modified electrode were premeditated by real sample investigation of MET present in pharmaceutical tablets with good recovery results to confirm the analytical pertinence of the proposed sensor.

Activated Screen-Printed Boron-Doped Diamond Electrode for Rapid and Highly Sensitive Determination of Curcumin in Food Products.

Due to a great interest in the beneficial properties of polyphenolic antioxidant curcumin (CCM), sensitive and accurate methods for determining CCM are needed. The purpose of our research was to develop a very simple, fast, and sensitive differential pulse adsorptive stripping voltammetric (DPAdSV) procedure using an electrochemically activated screen-printed boron-doped diamond electrode (aSPBDDE) for the determination of CCM. The activation of the SPBDDE was accomplished in a solution of 0.1 mol/L NaOH by performing five cyclic voltammetric scans in the range of 0-2 V, at ν of 100 mV/s. The changes in surface morphology and the reduction of the charge transfer resistance due to the activation of the electrode resulted in the amplification of the CCM analytical signal on the aSPBDDE. As a result, an extremely sensitive measurement tool was formed, which under optimized conditions (0.025 mol/L PBS of pH = 2.6, Eacc of 0.3 V, tacc of 90 s, ΔEA of 100 mV, ν of 150 mV/s, and tm of 10 ms) allowed us to obtain a limit of detection (LOD) of 5.0 × 10-13 mol/L. The aSPBDDE has proven to be a highly effective tool for the direct determination of CCM in food samples with high accuracy and precision. The results are in agreement with those obtained using ultra-high-performance liquid chromatography coupled with mass spectrometry and electrospray ionization (UHPLC-ESI/MS).

Bimetallic Cu-Zn Zeolitic Imidazolate Frameworks as Peroxidase Mimics for the Detection of Hydrogen Peroxide: Electrochemical and Spectrophotometric Evaluation.

A copper incorporated zeolitic imidazolate framework-8 (ZIF-8) has been synthesized and demonstrated to be a potential material for a peroxidase mimic. The resultant bimetallic Cu-Zn incorporated MOF is used for the dual mode sensing of hydrogen peroxide by following electrochemical as well as spectrophotometric methods. Using 3,3',5,5'-tetramethylbenzidine (TMB) as a chromogenic substrate, spectrophotometric studies are carried out, and the steady state kinetic parameters are determined for two different concentrations of Cu incorporated ZIF-8 (viz Cu@ZIF-8-1 and Cu@ZIF-8-2). It is found that both Cu@ZIF-8-1 and Cu@ZIF-8-2 exhibit more affinity toward the TMB substrate than the horseradish peroxidase (HRP) enzyme as indicated by the low Km values obtained for the substrate. Also, as the concentration of incorporated Cu increases, Vmax values are also found to be enhanced. Electrochemically, the Cu@ZIF-8 modified glassy carbon electrode (GCE) showed a good response for peroxide detection in the concentration range from 0.5 mM to 5 mM at a working potential of -0.25 V in PBS (pH 7.0) with a limit of detection (LOD) value of 0.46 mM and a sensitivity of 20.25 μA/mM. Further, the chromogenic substrate TMB is successfully immobilized on the electrode surface and subsequently used for the peroxide detection along with Cu@ZIF-8. Here, TMB acts as a mediator and shifted the working potential to 0.1 V in acetate buffer (pH 5.0) in the concentration range from 0.5 mM to 5 mM with an LOD value of 0.499 mM and a sensitivity of 0.097 μA/mM. Interestingly, the same electrode in PBS of pH 7.0 showed a response to peroxide at a working potential of -0.1 V in the concentration range from 0.5 mM to 5 mM with an LOD value of 0.143 mM and a sensitivity of 0.33 μA/mM. Moreover, the applicability of this material for peroxide sensing is evaluated using milk samples, and the proposed material is able to recover the peroxide present in milk. Thus, the bimetallic Cu-Zn MOF can be utilized for the dual mode sensing of peroxide and can be extended for various real time applications.

A β-Sitosterol Encapsulated Biocompatible Alginate/Chitosan Polymer Nanocomposite for the Treatment of Breast Cancer.

β–sitosterol is the most abundant type of phytosterol or plant sterol and can be found in various plant dietary sources including natural oils, soy products, and nuts. Numerous studies have demonstrated the potential therapeutic and clinical applications of β–sitosterol including lowering low-density lipoprotein and cholesterol levels, scavenging free radicals in the body, and interestingly, treating and preventing cancer. This study focuses on synthesizing and characterizing β–sitosterol encapsulated Alginate/Chitosan nanoparticles (β–sito–Alg/Ch/NPs) and evaluating their effectiveness in breast cancer treatment and their pharmacokinetic profile in vivo. The synthesized NPs, which incurred a mean size of 25 ± 1 nm, were extensively characterized in vitro for various parameters including surface charge and morphology. The NPs were further analyzed using DSC, FT-IR, thermogravimetry and X-ray diffraction studies. The release of β–sito from NPs was carried out in a bio-relevant medium of pH 7.4 and pH 5.5 and samples were drawn off and analyzed under time frames of 0, 8, 16, 32, 64, 48, 80, and 96 h, and the best kinetic release model was developed after fitting drug release data into different kinetic models. The metabolic activity of MCF-7 cells treated with the prepared formulation was assessed. The radical scavenging potential of β–sito–Alg/Ch/NPs was also studied. The pharmacokinetic parameters including Cmax, Tmax, half-life (t1/2), and bioavailability were measured for β–sito–Alg/Ch/NPs as compared to β–sito–suspension. The β–sito–Alg/Ch/NPs stability was assessed at biological pH 7.4. The % drug release in PBS of pH 7.4 reportedly has shown 41 ± 6% vs. 11 ± 1% from β–sito–Alg/Ch/NPs and β–sito–suspension. In acidic pH 5.5 mimicking the tumor microenvironment has shown 75 ± 9% vs. 12 ± 4% drug release from β–sito–Alg/Ch/NPs and β–sito–suspension. When compared to the β–sito–suspension, the β–sito–Alg/Ch/NPs demonstrated greater cytotoxicity (p < 0.05) and ~3.41-fold higher oral bioavailability. Interestingly, this work demonstrated that β–sito–Alg/Ch/NPs showed higher cytotoxicity due to improved bioavailability and antioxidant potential compared to the β–sito–suspension.

Chitosan-based formulation of hemagglutinin antigens for oculo-nasal booster vaccination of chickens against influenza viruses

Avian influenza viruses (AIVs) and especially highly pathogenic (HP) AIVs of the H5 and H7 subtypes are of both veterinary and public health concern worldwide. In response to the demand for effective vaccines against H5N1 HPAIVs, we produced recombinant protein based on hemagglutinin (HA), a protective viral antigen. A fragment of the HA ectodomain, with a multibasic cleavage site deletion, was expressed in Escherichia coli, refolded, and chromatographically purified from inclusion bodies. Finally, the protein was formulated in Tris-HCl buffer of pH 8.0 or PBS of pH 7.4 to obtain antigens denoted rH5–1 and rH5–2, respectively. The systemic prime and boost immunizations proved that rH5–1 adsorbed to aluminum hydroxide induces anti-H5 HA neutralizing antibodies and protective immune responses against H5N1 HPAIVs in chickens. The present studies were aimed at stimulating immune responses via the mucosal routes using the systemic prime-mucosal boost strategy. Efficacy trials were performed in commercial layer chickens. For systemic and mucosal immunizations, H5 HA antigens were adjuvanted with aluminum hydroxide and chitosan glutamate, respectively. The first dose of rH5–2 was administered subcutaneously, while its second dose was administered subcutaneously, intraocularly, oculo-nasally, or intranasally. rH5–1 was delivered to the subcutaneously primed chickens by the intranasal route. Post-vaccination sera were analyzed for anti-H5 HA antibodies, using homologous ELISA and heterologous FluAC H5 and hemagglutination inhibition tests. Intraocularly and oculo-nasally delivered rH5–2 mixed with chitosan glutamate was capable of stimulating anti-H5 HA IgY antibody responses in the subcutaneously primed chickens; however, it was ineffective when administered by the intranasal route. Efficient intranasal boosting was achieved using rH5–1. The enhanced production of antigen-specific antibodies was reflected in the development of H5-subtype specific and hemagglutination inhibiting antibodies. Conclusively, the subcutaneous prime and oculo-nasal boost vaccination is proposed as the target strategy for future optimization.

Comparative Study of Chronoamperometry of PANI/ZnO/Urease and PANI/MnO2/Urease Biosensors

Polyaniline (PANI) based electrochemically synthesized PANI/ZnO/Urease and PANI/MnO2/Ureasebiosensorshave been prepared. The stainless-steel transducer was used for electrodeposition using potentiostat. Chronoamperometric response of as-synthesized PANI/ZnO/Urease and PANI/MnO2/Urease biosensors in potential range 0.2 to 0.6 volt vs. reference electrode for time interval of 100 Sec in PBS of pH 7was carried out. The immobilization of urease on modified PANI/ZnO (15%) film, results in getting larger saturation current in10 sec suggests that the immobilized enzyme by physical adsorption method is well entrapped in PANI/ZnO matrix and show lesser degradation of the Urease. PANI/MnO2 matrix, show degradation of the Urease on account of the less stable curve.The decay of the saturation current in PANI/MnO2/Urease suggests the predominance of the degradation of enzyme layer over electron transfer at the electrode surface. PANI/ZnO matrix is found more suitable for the entrapment of Urease compared to the PANI/MnO2 matrix.

In Vitro Degradation of PHB/Bacterial Cellulose Biocomposite Scaffolds

The present work reported the preparation of biocomposites based on poly(3-hydroxybutyrate) (PHB), plasticizer, and bacterial cellulose (BC) by melt processing and their testing by means of thermal properties (DSC), water absorption, and in vitro degradation. The surface of the biocomposites was analyzed via atomic force microscopy (AFM). In vitro degradation of the biocomposites was evaluated by weight loss and thermal properties (DSC) assessment after the immersion of the specimens in phosphate-buffered saline solution (PBS of pH 7.4) over 20 days. The results showed that the BC can reduce the PHB crystallinity and promote its degradation under PBS medium. Moreover, it was found that the water absorption increased as the percentage of BC increased.

First Screen-Printed Sensor (Electrochemically Activated Screen-Printed Boron-Doped Diamond Electrode) for Quantitative Determination of Rifampicin by Adsorptive Stripping Voltammetry

In this paper, a screen-printed boron-doped electrode (aSPBDDE) was subjected to electrochemical activation by cyclic voltammetry (CV) in 0.1 M NaOH and the response to rifampicin (RIF) oxidation was used as a testing probe. Changes in surface morphology and electrochemical behaviour of RIF before and after the electrochemical activation of SPBDDE were studied by scanning electron microscopy (SEM), CV and electrochemical impedance spectroscopy (EIS). The increase in number and size of pores in the modifier layer and reduction of charge transfer residence were likely responsible for electrochemical improvement of the analytical signal from RIF at the SPBDDE. Quantitative analysis of RIF by using differential pulse adsorptive stripping voltammetry in 0.1 mol L−1 solution of PBS of pH 3.0 ± 0.1 at the aSPBDDE was carried out. Using optimized conditions (Eacc of −0.45 V, tacc of 120 s, ΔEA of 150 mV, ν of 100 mV s−1 and tm of 5 ms), the RIF peak current increased linearly with the concentration in the four ranges: 0.002–0.02, 0.02–0.2, 0.2–2.0, and 2.0–20.0 nM. The limits of detection and quantification were calculated at 0.22 and 0.73 pM. The aSPBDDE showed satisfactory repeatability, reproducibility, and selectivity towards potential interferences. The applicability of the aSPBDDE for control analysis of RIF was demonstrated using river water samples and certified reference material of bovine urine.

Platinum Nanoparticles/Poly(isoleucine) Modified Glassy Carbon Electrode for the Simultaneous Determination of Hydroquinone and Catechol

AbstractA new electrochemical sensor based on Poly(Isoleucine) modified glassy carbon electrode decorated with platinum nanoparticles (Pt/Poly(Isoleucine)/GCE) was developed for sensitive individual and simultaneous determination of hydroquinone (HQ) and catechol (CC). Scanning electron microscopy (SEM), Electrochemical impedance spectroscopy (EIS), Cyclic voltammetry (CV) and Differential pulse voltammetry (DPV) were performed in order to characterize the Pt/Poly(Isoleucine)/GCE nanocomposite. For simultaneous determination of HQ and CC, Pt/Poly(Isoleucine)/GCE showed wide linear range between the 0.01–100.0 μM. The detection limits were 0.006 μM for HQ and 0.005 μM for CC. The Pt/Poly(Isoleucine)/GC electrode exhibited good sensitivity and reliability in the simultaneous electroanalysis of two isomers in PBS of pH 7.5. The modified electrode was used to detect the isomers in naturel samples.

Electroanalysis of Carbendazim using MWCNT/Ca‐ZnO Modified Electrode

AbstractThe present research involves the report on electrochemical deportment of Carbendazim (MBC) at multiwalled carbon nanotubes and calcium‐doped zinc oxide nanoparticles altered nanocomposite based carbon paste electrode (MWCNTs/Ca‐ZnO‐CPE). The modified carbon paste evidenced manifest electrocatalytic behavior for MBC in 0.2 M phosphate buffer (PB) solutions. Cyclic voltammetry (CV), linear sweep voltammetry (LSV), and square wave voltammetry (SWV) techniques were used for the analysis. The working electrode assembly exhibits faster electron transfer of MBC with increase in the peak current. At bare CPE, MBC showed maximum peak current of 1.098 μA at potential 0.7568 V whereas at MWCNT/Ca‐ZnO/CPE peak current of 5.203 μA was observed at potential 0.7541 V in 0.2 M PBS of pH 7.0 at the sweep rate of 50 mV s−1. The synthesized 5 % Ca‐ZnO nanoparticles (NPs) were characterized by X‐ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X‐ray analysis (EDX), and Transmission electron microscopy (TEM) analysis. Various factors influencing the voltammetry of MBC such as pre‐concentration time, pH, sweep rate, and amount of MBC were studied and from the studies we observed that the response was found to be diffusion‐controlled. The concentration variation studies for MBC was watched in the linear working range of 0.01 μM to 0.45 μM and the detection limit was found by SWV technique.

Poly (fast sulphone black F) modified pencil graphite electrode sensor for serotonin

Development of sensitive and rapid biosensor for the investigation of serotonin has great significance because it is a key neurotransmitter and its unusual concentrations associated with serious mental disorders. In this study, an electrochemically modified serotonin-sensing electrode was fabricated by simple electropolymerisation of fast sulphone black F on pencil graphite electrode (PGE) using cyclic voltammetric technique. This modified pencil graphite electrode was applied for selective determination of serotonin (5-HT) and shows increased current responses of 5-HT in 0.2 M PBS of pH 7.4. The various analytical parameters such as effect of scan rate, concentration of 5-HT and solution pH were investigated. The diffusion controlled electrode process was observed for 5-HT and detection limit was found to be 1.7 μM. Interference study of 5-HT was analysed in presence of dopamine (DA) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV).

Fabrication of disposable electrochemical dopamine sensor using photoluminescent graphene oxide

Graphene oxide (GO) with photoluminescent property was prepared by modifiedHummer’s method. Spectroscopic and morphological studies were carried out using photoluminescence spectroscopy, UV-Vis absorption spectroscopy, FT-IR, XRD and FE-SEM. Electrochemical dopamine sensor was fabricated by drop casting GO onto screen printed carbon electrodes (SPCE). Cyclic voltammogram, differential pulse voltammogram and amperometry were performed to test the fabricated sensor. The sensor exhibits wide detection range of 12.5 μM to 1 mM dopamine concentrations in 0.1 M PBS of pH 7.4. The major interferents such as ascorbic acid shown negligible current response compared to dopamine.

Carbon Quantum Dot-Modified Carbon Paste Electrode-Based Sensor for Selective and Sensitive Determination of Adrenaline.

A carbon quantum dot-based carbon paste electrode was fabricated and used for the determination of adrenaline (AD) at the nanomolar level. This fabricated electrode exhibited tremendous electrocatalytic activity for the oxidation of adrenaline in supporting electrolyte (PBS of pH 7.4). Scan rate variation studies with the modified electrode revealed that the overall electrode process was controlled by a diffusion process. A lower detection limit of 6 nM was achieved by chronoamperometry. Interference by biological molecules such as serotonin (5-HT) and ascorbic acid (AA) in the electrochemical oxidation of AD on the fabricated electrode was tested. It was observed that with the modified electrode, the selective determination of AD was possible. Further, with the fabricated electrode, simultaneous analysis of AA, AD, and 5-HT was performed, and it was observed that the overlapped peaks of these analytes on the naked electrode were well resolved into three peaks on the modified electrode. Along with decent sensitivity and selectivity, the electrode also showed higher stability and antifouling nature. The real-time application of the projected scheme was proven by employing the said electrode for adrenaline in adrenaline bitartrate injections.

Electrochemical behavior of flufenamic acid at amberlite XAD-4 resin and silver-doped titanium dioxide/ amberlite XAD-4 resin modified carbon electrodes.

Novel sensors based on carbon paste assorted with amberlite XAD-4 resin and silver-doped titanium dioxide/amberlite XAD-4 resin (Ag-TiO2/XAD) were designed and employed for sensitive detection of flufenamic acid (FFA). The main objective of this study is to develop novel electrochemical sensors for more sensitive and selective detection of FFA and to propose its oxidation mechanism. In this perspective, we have developed modified electrodes using amberlite XAD-4 matrix and Ag-TiO2/XAD-4 mixture. These sensors when used in conjunction with different voltammetric techniques to observe enhanced outcome on FFA electrode reaction in PBS of pH 7.0. Our data confirmed exceptional stability, sensitivity, and quick responses for FFA. The effect of modifier, analyte concentration, pH of buffer solution, pre-concentration time, and sweep rates on electrochemical behavior of FFA was investigated. The current intensities were linearly proportional to the concentration of FFA. From the calibration plot of different concentrations of FFA, the detection limit of 3.6 nM at XAD-CPE and 1.2 nM, respectively at AgTiO2/XAD-CPE were obtained. The estimation of FFA in biological as well as clinical samples was achieved using the chemically modified electrodes.

A polyethylenimine-based diazeniumdiolate nitric oxide donor accelerates wound healing.

Nitric oxide (NO) plays a pivotal role in the cutaneous healing process and a topical supplement of NO is beneficial for wound repair. In this work, a novel polyethylenimine (PEI) based diazeniumdiolate nitric oxide donor was prepared. The obtained polymer (PEI-PO-NONOate) was characterized by Fourier transform infrared (FTIR) spectroscopy, UV-vis absorption spectra, and nuclear magnetic resonance (NMR). The PEI-PO-NONOate polymer was stable under anhydrous conditions at different temperatures. A total of 0.57 μmol gaseous NO was released from 1.0 mg of the PEI-PO-NONOate polymer in PBS of pH 7.4 and it presented a proton-driven release pattern. Furthermore, the PEI-PO-NONOate polymer exhibited a controlled release profile sustained for over 30 hours within the polyethylene glycol (PEG) mixture system. Cytotoxicity evaluation was performed on L929 cells. Full-thickness excisional cutaneous wound models of mice were prepared and the PEI-PO-NONOate polymer was applied to investigate its effects on wound healing. The results revealed that the PEI-PO-NONOates exhibited good biocompatibility. It was also found that the PEI-PO-NONOate polymer promoted cutaneous wound healing and closure with enhanced granulation tissue formation, collagen deposition, and angiogenesis, as compared to the control. In summary, a novel nitric oxide releasing polymer with high loading efficiency and a controlled release profile was developed which presented the potential for application in the acceleration of cutaneous wound healing.

A novel nanocomposite based on gold nanoparticles loaded on acetylene black for electrochemical sensing of the anticancer drug topotecan in the presence of high concentration of uric acid

In this study, a new voltammetric nanosensor was constructed by the decoration of acetylene black (AB) with gold nanoparticles (AuNPs) using glassy carbon paste (GCP) as a cross linker (nano-AB-AuNPs/GCPE) for determination of anticancer topotecan (TPT) drug. Moreover, from the response characteristics of cyclic voltammetry (CV) and square wave voltammetry (SWV), it was observed that TPT could be effectively accumulated at nano-AB-AuNPs/GCPE and resulted in a sensitive anodic peak current in PBS of pH 6.0. The surface area, electrical conductivity and catalytic performance of the modified electrode improved on account of the formation of nano-AB-AuNPs materials, thereby enhancing the sensitivity of the nanosensor. Under optimal conditions, a novel electrochemical method based on the nano-AB-AuNPs/GCPE sensor with high selectivity, high sensitivity and high anti-interference ability was developed for the determination of TPT. Furthermore, the electrochemical oxidation of TPT reveals an excellent linearity in the range of 1.99 × 10−9 to 6.71 × 10−7 M of TPT with a detection limit of 1.64 × 10−11 M (6.91 × 10−3 ng/mL). The TPT as a preconcentration agent showed chemical selectivity, so, the nanosensor was successfully applied for the determination of TPT in the presence of high concentrations of uric acid. Moreover, the method was employed efficiently to detect TPT in blood serum and urine samples, with satisfactory recoveries ranging from 98.16% to 100.76%.

Electrochemical Sensor for the Determination of Paracetamol at Carbamazepine Film Coated Carbon Paste Electrode

AbstractThe electrochemical behavior of paracetamol (PC) was investigated at carbamazepine (CBZ) film coated carbon paste electrode in 0.2 M PBS of pH 7.4 by cyclic voltammetric technique. The modified electrode was exhibited a good electrochemical activity towards the oxidation of paracetamol, which results in a noticeable improvement of the peak currents and feasible oxidation as compared to the bare carbon paste electrode. Under optimal experimental conditions the electrochemical response to PC was linear in the concentration range from 1.0×10−4M to 3.94×10−4M with a detection limit of 0.24 μM by cyclic voltammetric technique. The sensitivity, long-term stability, reproducibility was shown by the modified electrode. Finally, the proposed method was successfully applied to determine PC in pharmaceutical samples.

Niacin Film Coated Carbon Paste Electrode Sensor for the Determination of Epinephrine in Presence of Uric Acid: A Cyclic Voltammetric Study

Voltammetric resolution of neurotransmitter epinephrine (EP) in presence if uric acid (UA) was achieved at niacin film coated carbon paste electrode (niacin/CPE) in 0.2 M PBS of pH 7.4 by cyclic voltammetry (CV) technique. The fabricated electrode remarkably enhanced an electrocatalytic activity towards the oxidation of epinephrine, resulting in the irreversible general 2-electrontransfer adsorption controlled phenomenon. The effect of several experimental parameters were discussed. Such as, scan rate, pH and concentration. Under optimal conditions, the anodic peak current (Ipa) was proportional to epinephrine concentration over the range 20.66-174.4 μM, (r2=0.9976) with a detection limit of 11.3 nM by CV technique. The sensitive, selective and reproducible result obtained at the niacin/CPE. Finally, the developed method was successfully applied for determination of epinephrine in pharmaceutical samples.

Development of thermosensitive microgel-loaded cotton fabric for controlled drug release

COS-g-PVCL copolymer was synthesized and infiltrated into CaCO3 particles to prepare thermosensitive porous microgels which exhibited phase transition behavior at the temperature that was similar to the lower critical solution temperature(LCST) of copolymer. The incorporation of microgel to cotton was done by pad-dry-cure method from aqueous microparticle dispersion that contained citric acid as a crosslinking agent. In vitro drug release experiments were performed at two different temperatures (25 and 37°C) in PBS of pH 7.4 to study its drug release behavior with response to temperature. Due to the shrinkage of microgels, drug release profiles obtained were found to have enhanced release for aloin when the temperature was above LCST than other release conditions. Microgel-loaded fabrics proved to be in vivo biocompatible by skin irritation studies and displayed an obviously high water vapor permeability at 40°C. The MTT assay showed no obvious cytotoxicity of microgel-loaded cotton against mouse fibroblast cells within 5days. The results obtained demonstrated the potential use of the thermos-responsive microgel-loaded cotton fabrics as a textile-based drug delivery system for treating sunburn or skin care.

PH-Sensitive biodegradable PMAA2-b-PLA-b-PMAA2 H-type multiblock copolymer micelles: synthesis, characterization, and drug release applications

pH-Sensitive biodegradable polymethacrylic acid-block-polylactic acid-block-polymethacrylic acid (PMAA2-b-PLA-b-PMAA2) H-type multiblock copolymers were synthesized by atom transfer radical polymerization. The copolymer structure and molecular weight were characterized by FT-IR, 1H NMR, and gel permeation chromatography. The physicochemical characterization revealed that the copolymers could spontaneously form spherical core–shell micelles in aqueous solution, with critical aggregation concentration of about 19.7–32.5 mg L−1 and the hydrodynamic diameters below 200 nm. Zeta potentials measurements disclosed that the copolymer micelles were negatively charged due to ionized carboxyl groups in various PBS solutions. The H-type block copolymer micelles exhibited pH- sensitivity, as expected; and the hydrophobic anticancer drugs, 10-hydroxycamptothecin, and paclitaxel, had faster release rate in PBS solution of pH 5.6–7.4 than in PBS of pH 1.4, which was important for applications in the therapy of small intestine cancers. The copolymer micelle aggregates were proved to be biodegradable, and the degradation rates changed with copolymer compositions and environmental media. The micelle drug formulation indicated pH-dependent cytotoxicity and was thus capable of effectively killing the intestinal cells while avoiding doing harm to stomach. The biodegradable pH-sensitive PMAA2-b-PLA-b-PMAA2 H-type copolymer micelles can be used as water-insoluble drug targeting release carriers for targeted treatment of intestine cancers.