Hollow silica nanotubes for immobilization of penicillin G acylase enzyme

Magnetic thermosensitive polymer composite carrier with target spacing for enhancing immobilized enzyme performance

A novel magnetic thermosensitive polymer composite carrier with target spacing was developed. In this strategy, thermosensitive polymer grafted on magnetic Fe₃O₄ for enhancing immobilized penicillin G acylase (PGA) performance and introduce immobilized target spacing into magnetic carriers for the first time. Fe₃O₄ nanoparticles were synthesized by a reverse microemulsion method. The modifier used was the silane coupling agent γ-methylacryloxypropyl trimethoxysilane (KH570) and then reacting with a reversible-adaptive fragmentation chain transfer (RAFT) reagent, 2-cyano-2-propyldodecyl trithiocarbonate (CPDTC). The thermo-sensitive nanoparticle-composite carrier of Fe₃O₄-grafted-poly N, N-diethyl acrylamide-block-poly β-Hydroxyethyl methacrylate-block-random copolymer of glycidyl methacrylate and methyl methacrylate (Fe₃O₄-g-PDEA-b-PHEMA-b-P(MMA-co-GMA)) were synthesized by RAFT polymerization technique that used N, N-diethyl acrylamide (DEA), β-Hydroxyethyl methacrylate (HEMA), Glycidyl methacrylate (GMA) and Methyl methacrylate (MMA) as monomer, then which were employed as functional carriers for the immobilization of PGA. Within the carrier, the epoxy group of GMA segment was a target immobilization site for PGA and the introduction of MMA reflected the target space of immobilized PGA to improve catalytic activity and catalytic activity recovery rate of the immobilized PGA. Characterizations demonstrated that the triblock copolymers grafted Fe₃O₄ nanoparticles were successfully fabricated by the structure design. Besides, under these circumstances the enzyme activity (EA), enzyme loading capacity (ELC) and catalytic activity recovery ration (CAR) reached 31235 U/g, 128.39 mg/g and 93.32 %, respectively. The catalytic activity of immobilized PGA maintained 87.4 % of initial value and the recovery ratio (R) of immobilized PGA reached 96.22 % after recycling 12 times. Furthermore, the immobilized PGA exhibited advantages of low temperature homogeneous catalysis and magnetic separation, which indicated broad application prospects in the biocatalysts' field.

Simple Purification and Immobilization of His-Tagged Organophosphohydrolase from Cell Culture Supernatant by Metal Organic Frameworks for Degradation of Organophosphorus Pesticides

Coordinating unsaturated metal sites (CUS) on the surface of metal-organic frameworks (MOFs) could be used to adsorb His-tagged proteins. The specific adsorption between CUS and His-tagged proteins could reduce preparation steps, shorten preparation time, and could also avoid the binding between the metal ion of metalloenzyme active center and the chelating agent to ensure the enzyme activity. In this study, MIL-88A was synthesized by hydrothermal method and used to purify and immobilize His-tagged organophosphohydrolase (OpdA) in one step for organophosphate bioremediation. Under optimized conditions, OpdA@MIL-88A had a maximal activity of 1554 U/g_protein, which was nearly 5 times higher than free OpdA. Compared with free OpdA, OpdA@MIL-88A exhibited improved organic solvent tolerance, SDS tolerance, thermal stability, and storage stability. OpdA@MIL-88A was used to degrade organophosphorus pesticides on grapes and cucumbers. After reuse 6 times, OpdA@MIL-88A retained more than 66% and 61% of the initial activity, respectively. Therefore, this proposed strategy provided a facile and effective method for degradation of organophosphorus pesticides.

A novel Fe–La-doped hierarchical porous silica magnetic adsorbent for phosphate removal

A novel Fe–La modified magnetic hierarchical porous silica was synthesized by an impregnation method to adsorb phosphate in aquatic ecology.

Facile immobilization of enzyme on three dimensionally ordered macroporous silica via a biomimetic coating

Penicillin G acylase was immobilized onto 3DOM silica via a biomimetic coating method and the stabilities were improved significantly.

Fluorescent mesoporous silica nanotubes incorporating CdS quantum dots for controlled release of ibuprofen

Mesoporous silica nanotubes (MSNTs) and amine-functionalized MSNTs (NH(2)-MSNTs) have been successfully synthesized via a sol-gel route using needle-like CaCO(3) nanoparticles as inorganic templates and post-modification with 3-aminopropyltriethoxysilane. Subsequently, the preformed nanotubes were functionalized with blue fluorescent CdS quantum dots, as demonstrated by transmission electron microscopy and confocal laser scanning microscopy. The morphology and microstructure of the produced materials were characterized by scanning electron microscopy and N(2) adsorption-desorption measurements. A comparative study of the capacity of several kinds of nanotube materials to store ibuprofen indicated that the drug-loading amount in CdS-NH(2)-MSNTs (CdS-incorporated NH(2)-MSNTs) could reach up to 740 mg/g silica, similar to that in as-prepared MSNTs (762 mg/g silica) and NH(2)-MSNTs (775 mg/g silica). Drug release studies in simulated body fluid revealed that the loaded ibuprofen released from amine-functionalized systems at a significantly lower release rate as compared to that from amine-free systems, and the incorporation of CdS quantum dots had nearly no effect on the ibuprofen release process. Further study on the ibuprofen release from CdS-NH(2)-MSNTs in other media, i.e. borate buffer saline, pure water and normal saline, indicated that CdS-NH(2)-MSNTs are pH- and ion-sensitive drug carriers, which should facilitate controlled drug delivery and disease therapy.

Synthesis of alpha-chymotrypsin/polymer composites by a reverse micelle/gas antisolvent method

Alpha-chymotrypsin (CT)/polyvinylpyrrolidone (PVP) composites was synthesized by combination of reverse micelles and CO(2). In this method, the two reverse micellar solutions containing CT and PVP, respectively, were first mixed, then compressed CO(2) was used as an antisolvent to precipitate the CT and PVP simultaneously and CT/PVP composites were successfully prepared. The morphology of the obtained CT/PVP composites was characterized by transmission electron microscopy (TEM). The FTIR spectra of the composites showed that there was interaction between CT and PVP. The storage activity of the enzyme immobilized on the polymer by this method was higher than that of the pure enzyme. This method has some advantages and can be easily applied to the synthesis of some other enzyme/polymer composites.