Stimuli-Sensitive Hydrogel Based on N-Isopropylacrylamide and Itaconic Acid for Entrapment and Controlled Release ofCandida rugosaLipase under Mild Conditions

Abstract

Stimuli responsive pH- and temperature-sensitive hydrogel drug delivery systems, as those based on N-isopropylacrylamide (NiPAAm) and itaconic acid (IA), have been attracting much of the attention of the scientific community nowadays, especially in the field of drug release. By adjusting comonomer composition, the matrix is enabled to protect the incorporated protein in the highly acidic environment of upper gastrointestinal tract and deliver it in the neutral or slightly basic region of the lower intestine. The protein/poly(NiPAAm-co-IA) hydrogels were synthetized by free radical crosslinking copolymerization and were characterized concerning their swelling capability, mechanical properties, and morphology. The pore structure and sizes up to 1.90 nm allowed good entrapment of lipase molecules. Model protein, lipase from Candida rugosa, was entrapped within hydrogels upon mild conditions that provided its protection from harmful environmental influences. The efficiency of the lipase entrapment reached 96.7%, and was dependent on the initial concentration of lipase solution. The swelling of the obtained hydrogels in simulated pH and temperature of gastrointestinal tract, the lipase entrapment efficiency, and its release profiles from hydrogels were investigated as well.

Synthesis of Thermo-Sensitive Hydrogels from Free Radical Copolymerization of NIPAAm with MBA Initiated by Atmospheric Plasma Treatment

“…The higher the MBA concentration, the higher the crosslinking efficiency is, independently on the initial NIPAAm monomer concentration and incident plasma power. The decreased swelling capacity of p(NIPAAm‐co‐MBA) hydrogels could also be related to the slower relaxation time of the polymeric chains with an increase in crosslinking efficiency and also to smaller size porosity of the crosslinked hydrogels as previously reported …”

Selection of Lipases for the Synthesis of Biodiesel from Jatropha Oil and the Potential of Microwave Irradiation to Enhance the Reaction Rate

“…The immobilization of lipases by several techniques on solid supports is a well-documented technology that allows application of these enzymes in several industrial processes, including biodiesel synthesis [15–17]. Lipases have been immobilized using different protocols as physical adsorption on hydrophobic and ionic exchange resins, covalent attachment on highly activated supports, and encapsulation in organic matrices [16, 18–20]. Covalent attachment of nucleophilic groups of lipases (N-terminal and hydroxyl groups) on highly activated supports (e.g., epoxy or aldehyde groups on the support surface introduced after the activation step) may promote the stabilization of their three-dimensional structures, thus reducing possible conformational changes induced by any distorting agents such as solvents and temperature [18, 21–24].…”

Thermogels containing sulfated hyaluronan as novel topical therapeutics for treatment of ocular surface inflammation

“…FTIR spectra ( Fig. 1 b) further support the formation of PN-NH 2 , as verified by (i) the visibility of amide bands I and II at 1657 and 1546 ​cm −1 , (ii) the disappearance of monomer characteristic peaks at 1617 ​cm −1 ​(C C) and 1411 ​cm −1 (=CH 2 ), and (iii) the occurrence of primary amine (NH 2 ) peak at 3438 ​cm −1 [ 45 , 46 ]. The sulfation degree in the sHA specimens were characterized using carbon-13 NMR ( 13 C NMR), as shown in Fig.…”