Chiral resolution of (±)-flurbiprofen using molecularly imprinted hydrazidine-modified cellulose microparticles.

Flurbiprofen (FP) is one of the non-steroidal anti-inflammatory drugs (NSAIDs) commonly used to treat arthritic conditions. FP has two enantiomers: S-FP and R-FP. S-FP has potent anti-inflammatory effects, while R-FP has nearly no such effects. Herein, molecularly imprinted microparticles produced from hydrazidine-cellulose (CHD) biopolymer for the preferential uptake of S-FP and chiral resolution of (±)-FP were developed. First, cyanoethylcellulose (CECN) was synthesized, and the -CN units were transformed into hydrazidine groups. The developed CHD was subsequently shaped into microparticles and ionically interacted with the S-FP enantiomer. The particles were then imprinted after being cross-linked with glutaraldehyde, and then the S-FP was removed to provide the S-FP enantio-selective sorbent (S-FPCHD). After characterization, the optimal removal settings for the S- and R-FP enantiomers were determined. The results indicated a capacity of 125 mg/g under the optimum pH range of 5-7. Also, S-FPCHD displayed a noticeable affinity toward S-FP with a 12-fold increase compared to the R-FP enantiomer. The chiral resolution of the (±)-FP was successfully attempted using separation columns, and the outlet sample of the loading solution displayed an enantiomeric excess (ee) of 93 % related to the R-FP, while the eluent solution displayed an ee value of 95 % related to the S-FP.

Rapid adsorption of acid dyes using Cu(II) thiourea modified cellulose complex.

In the present work, the acid dyes namely, eriochrome cyanine R (ECR) and 2-(4-Sulfo phenyl azo)-1,8 dihydroxy-3,6 naphthalene disulfonic acid, trisodium salt (SPADNS) were effectively adsorbed by Cu(II)-thiourea modified cotton fibers (Cu(II)/Tu-MC) complex. FTIR, SEM, XPS analysis, thermogravimetric analysis, and potentiometric titration were utilized for characterization. The impact of the fundamental adsorption parameters was systematically investigated. The results reveal that the adsorption of ECR and SPADNS acid dyes occurs via a metal-coordination mechanism. Furthermore, the adsorption process follows the 2nd order kinetic model and Langmuir model adsorption isotherm. The Cu(II)/Tu-MC shows high adsorption capacities of 0.27 and 0.22 mmol/g for ECR and SPADNS, respectively. These findings indicate that the cationization of cellulose fibers with metal ions is a promising and efficient strategy toward enhancing the adsorption of acid dyes.

Designing and investigation of photo-active gellan gum for the efficient immobilization of catalase by entrapment.

A photo-active gellan gum (Gel) derivative was developed by amide bond combination with trans-4-[p-(amino)styryl]pyridine (SP). The SP-Gel was cross-linked by UV curing via the intermolecular 2π + 2π cycloaddition of the inserted SP-CH=CH- moieties. The chemical structure of the obtained photo-crosslinkable biopolymer was investigated before and after the UV curing and the progress of the performed 2π + 2π cycloaddition-based cross-linking was detected via UV-visible light spectra. SP-Gel was evaluated as a polymeric matrix for the immobilization of catalase via entrapment technique. The synthesized biopolymer was mixed with the catalase and molded in the form of membranes that were UV cured to encapsulate the enzyme. The membranes were able to entrap 0.75 mg/cm2 with retained activity reached above 95%. The immobilized catalase displayed higher thermal stability and higher resistance toward the environmental pH disturbances compared to the free enzyme. Also, despite the observed lower catalase-H2O2 affinity upon the entrapment that was indicated from the performed kinetic studies, the reusability and storage stability experiments revealed the economic value of the entire process by preserving around 95% and 83% of the initial catalase activity after the fifth and tenth operation cycles, respectively.

Surface molecularly imprinted amino-functionalized alginate microspheres for enantio-selective extraction of l-ascorbic acid.

A surface molecular imprinting technique was utilized in the fabrication of an enantio-selective adsorbent based on amino-functionalized alginate microspheres for chiral resolution of ascorbic acid. Alginate microspheres were first strengthened via epichlorohydrin (ECH) covalent cross-linking then functionalized with amino groups through graft copolymerization of polyacrylamide (PAm) followed by Hofmann degradation. Surface molecular imprinting was then performed under mild conditions by ionic interaction between the surface incorporated amine groups and the template l-ascorbic acid enantiomers followed by cross-linking with glyoxal. l-Ascorbic acid enantio-selective adsorbent (LA-Alg) was finally obtained by removing the template molecules out of the cross-linked network formed on the surface of the modified alginate particles. The synthetic steps were monitored using elemental analysis and FTIR spectra. Also, the surface morphologies of the native unmodified alginate along with both imprinted and non-imprinted adsorbent particles were examined by SEM. Moreover, the crystalline profile and thermal properties of both native and modified samples were investigated using XRD spectra and thermogravimetric analysis (TGA), respectively. The effect of pH on the extraction process was studied and indicated that the maximum adsorption was obtained at pH 4. Also, adsorption isotherms over LA-Alg adsorbent displayed the best fit with Langmuir model with maximum adsorption capacity 116 ±â€¯1 and 67 ±â€¯1 mg/g with respect to both l- and d-ascorbic acid, respectively. Moreover, the chiral resolution experiment using batch technique indicated 72% enantiomeric excess.