Conjugation of α-chymotrypsin on a polymeric hydrophilic nanolayer covering magnetic nanoparticles

Solid-phase synthesis of protein-polymers on reversible immobilization supports

Facile automated biomacromolecule synthesis is at the heart of blending synthetic and biologic worlds. Full access to abiotic/biotic synthetic diversity first occurred when chemistry was developed to grow nucleic acids and peptides from reversibly immobilized precursors. Protein-polymer conjugates, however, have always been synthesized in solution in multi-step, multi-day processes that couple innovative chemistry with challenging purification. Here we report the generation of protein-polymer hybrids synthesized by protein-ATRP on reversible immobilization supports (PARIS). We utilized modified agarose beads to covalently and reversibly couple to proteins in amino-specific reactions. We then modified reversibly immobilized proteins with protein-reactive ATRP initiators and, after ATRP, we released and analyzed the protein polymers. The activity and stability of PARIS-synthesized and solution-synthesized conjugates demonstrated that PARIS was an effective, rapid, and simple method to generate protein-polymer conjugates. Automation of PARIS significantly reduced synthesis/purification timelines, thereby opening a path to changing how to generate protein-polymer conjugates.

Bio-waste derived dialdehyde cellulose ethers as supports for α-chymotrypsin immobilization

Enzyme immobilization is an important technique to enhance stability, storability and reusability of enzymes. In the present work, pine needles, a forest bio-waste, were used as a feedstock of cellulose to synthesize new materials as supports for immobilization of α-chymotrypsin (CT) enzyme. The extracted cellulose from pine needles was etherified with different alkyl bromides (RBr) and etherified products were further modified to dialdehyde via oxidation with NaIO4 to get the desired products, dialdehyde cellulose ethers (ROcellCHO). CT was then covalently immobilized onto as-synthesized dialdehyde cellulose ethers via Schiff-base formation, i.e., imine linkage. The synthesized products and enzyme immobilization were confirmed by different characterization techniques and the activity assay of the free and the immobilized CT was carried out using standard protocol with variation of different parameters such as temperature, pH and substrate concentration. The storage stability and reusability of the immobilized CT were also investigated. CT activity was also studied in simulated physiological conditions in the artificial gastric fluid and artificial intestinal fluid. Artificial neural network (ANN) model was employed to correlate the relationship with% relative activity and time, temperature and pH affecting enzyme activity. A good correlation of experimental data was predicted by ANN model.

Superparamagnetic Fe3O4nanoparticles modified by water-soluble and biocompatible polyethylenimine for lipase immobilization with physical and chemical mechanisms

A solvothermal method was applied to prepare magnetic nanoparticles. And after being coated by PEI, the nanoparticles were able to be modified by glutaraldehyde. Then the supports can be used to immobilize lipase covalently, as well asviaionic exchange.

Calcium alginate beads encapsulated PMMA-g-CS nano-particles for α-chymotrypsin immobilization

Chitosan grafted with polymethyl methacrylate (PMMA-g-CS) was prepared via a free-radicals polymerization technique as a carrier for enzyme immobilization. α-Chymotrypsin (CT), as an enzyme model in this study, was immobilized onto the prepared PMMA-g-CS via covalent bonding. Calcium alginate (CA) beads were developed for encapsulating PMMA-g-CS-CT to produce PMMA-g-CS-CT/CA composite beads. Morphology and size of PMMA-g-CS particles were investigated by TEM and found to be in the nanoscale. The structure and surface morphology of the beads before and after immobilization process were characterized by FT-IR and SEM, respectively. Both the bound CT content and relative activity of immobilized enzyme were measured. A higher retained activity (about 97.7%) obtained for the immobilized CT at pH 9 for 24 h. The results indicated that immobilized CT maintained excellent performance even after 25 reuses and retained 75% from its original activity after 60 days of storage at 25 °C.

Preparation of superparamagnetic Fe3O4@alginate/chitosan nanospheres for Candida rugosa lipase immobilization and utilization of layer-by-layer assembly to enhance the stability of immobilized lipase

Superparamagnetic alginate nanospheres with diameter of 50 nm were prepared by self-assembly of alginate in the Ca(2+) solution; and then superparamagnetic alginate/chitosan nanospheres, which have positive charge and could adsorb lipase directly, were obtained with a following assembly of chitosan based on the electrostatic interaction between alginate and chitosan. Subsequently, oxidic poly (ethylene glycol) was used to functionalize the magnetic alginate/chitosan nanospheres. Thus, the magnetic nanospheres with aldehyde groups and a brushlike structure were formed. With various characterizations, it was verified that the magnetic alginate/chitosan nanospheres held small diameters (around 60 nm) and displayed superparamagnetism with high saturation magnetization. The Candida rugosa lipase (CRL), meanwhile, was immobilized onto the magnetic alginate/chitosan nanospheres by electrostatic adsorption and covalent bonding, respectively. Afterward, a layer-by-layer (LBL) assembly process was utilized to coat the immobilized CRL (ICRL) with covering layers made up of alginate and chitosan. After studying the properties of ICRL such as activity, kinetic behaviors, stability and reusability, it was proved that the ICRL prepared with two methods displayed more excellent properties than that prepared with electrostatic adsorption only. Additionally, coating ICRL with covering layers showed good effect on improving the stability of ICRL.

Development of peptide and protein nanotherapeutics by nanoencapsulation and nanobioconjugation

The targeted delivery of therapeutic peptide by nanocarriers systems requires the knowledge of interactions of nanomaterials with the biological environment, peptide release, and stability of therapeutic peptides. Therapeutic application of nanoencapsulated peptides are increasing exponentially and >1000 peptides in nanoencapsulated form are in different clinical/trial phase. This review covers current scenario of therapeutic protein and peptides encapsulation on polymer to metallic nanocarriers including methods of protein encapsulation, peptide bioconjugation on nanoparticles, stability enhancement of encapsulated proteins and its biomedical applications.

Magnetic particle-based hybrid platforms for bioanalytical sensors

Biomagnetic nano and microparticles platforms have attracted considerable interest in the field of biological sensors due to their interesting physico-chemical properties, high specific surface area, good mechanical stability and opportunities for generating magneto-switchable devices. This review discusses recent advances in the development and characterization of active biomagnetic nanoassemblies, their interaction with biological molecules and their use in bioanalytical sensors.