Enzyme immobilization on quercetin capped gold and silver nanoparticles for improved performance

Immobilization of Dextranase Obtained from the Marine Cellulosimicrobium sp. Y1 on Nanoparticles: Nano-TiO2 Improving Hydrolysate Properties and Enhancing Reuse

Dextranase is widely used in sugar production, drug synthesis, material preparation, and biotechnology, among other fields. The immobilization of dextranase using nanomaterials in order to make it reusable, is a hot research topic. In this study, the immobilization of purified dextranase was performed using different nanomaterials. The best results were obtained when dextranase was immobilized on titanium dioxide (TiO₂), and a particle size of 30 nm was achieved. The optimum immobilization conditions were pH 7.0, temperature 25 °C, time 1 h, and immobilization agent TiO₂. The immobilized materials were characterized using Fourier-transform infrared spectroscopy, X-ray diffractometry, and field emission gun scanning electron microscopy. The optimum temperature and pH of the immobilized dextranase were 30 °C and 7.5, respectively. The activity of the immobilized dextranase was >50% even after 7 times of reuse, and 58% of the enzyme was active even after 7 days of storage at 25 °C, indicating the reproducibility of the immobilized enzyme. The adsorption of dextranase by TiO₂ nanoparticles exhibited secondary reaction kinetics. Compared with free dextranase, the hydrolysates of the immobilized dextranase were significantly different, and consisted mainly of isomaltotriose and isomaltotetraose. The highly polymerized isomaltotetraose levels could reach >78.69% of the product after 30 min of enzymatic digestion.

Surface Engineered Peroxidase-Mimicking Gold Nanoparticles to Subside Cell Inflammation

The smart design of nanoparticles with varying surfaces may open a new avenue for potential biomedical applications. Consequently, several approaches have been established for controlled synthesis to develop the unique physicochemical properties of nanoparticles. However, many of the synthesis and functionalization methods are chemical-based and might be toxic to limit the full potential of nanoparticles. Here, curcumin (a plant-derived material) based synthesis of gold (Au) nanoparticles, followed by the development of a suitable exterior corona using isoniazid (INH, antibiotic), tyrosine (Tyr, amino acid), and quercetin (Qrc, antioxidant), is reported. All these nanoparticles (Cur-Au, Cur-Au^INH, Cur-Au^Tyr, and Cur-Au^Qrc) possess inherent peroxidase-mimicking natures depending on the surface corona of respective nanoparticles, and they are found to be excellent candidates for free radical scavenging action. The peroxidase-mimicking nanoparticle interactions with red blood cells and mouse macrophages confirmed their hemo- and biocompatible nature. Moreover, these surface-engineered Au nanoparticles were found to be suitable in subsiding key pro-inflammatory cytokines such as interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β). The inherent peroxidase-mimicking behavior and anti-inflammatory potential without any significant toxicity of these nanoparticles may open new prospects for nanomedicine.

Delineating the Role of Tailored Gold Nanostructures at the Biointerface

Gold (Au) has emerged as a superior element, because of its widespread applications in electronic and medical fields. The desirable physical, chemical, optical, and inherent enzyme-like properties of Au are efficiently exploited for detection, diagnostic, and therapeutic purposes. Au offers a unique advantage of fabricating gold nanostructures (GNS) having exact physical, chemical, optical, and enzyme-like properties required for the specific biomedical application. In this Review, the emerging trend of GNS for various biomedical applications is highlighted. Some notable structural and chemical modifications achieved for the detection of biomolecules, pathogens, diagnosis of diseases, and therapeutic applications are discussed in brief. The limitations of GNS during biomedical usage are highlighted and the way forward to overcome these limitations are discussed.

The bonding nature of the chemical interaction between trypsin and chitosan based carriers in immobilization process depend on entrapped method: A review

The review article is dedicated to a comprehensive study of the chemical bond formed during the immobilization of the proteolytic enzyme pancreatic trypsin in chitosan-based polymer matrixes and its derivatives. The main focus of the study is to describe the chemical bond that causes immobilization between chitosan based carriers and trypsin. Because the nature of the chemical bond between the carrier and trypsin is a key factor in determining the area of application of the conjugate. It has been found out that after the chemical nature of functional groups, their degree of ionization, the structure of the chemical cross-linking, the medium pH and ionic strength of chitosan are modified, the mechanism of trypsin immobilization is affected. As a result, the attraction enzyme to the matrix occurs due to polar covalent and hydrogen bonds, as well as electrostatic, hydrophobic, Van der Waals forces. The collected research works on the immobilization of trypsin on chitosan-based carriers have been systematized in the paper and shown schematically in subsystems according to the type of chemical interaction. It has been shown that the immobilization of trypsin on chitosan based matrixes occur more often due to the covalent and hydrogen bonds between the protein and the carrier.

Immobilization of Dextranase on Nano-Hydroxyapatite as a Recyclable Catalyst

The immobilization technology provides a potential pathway for enzyme recycling. Here, we evaluated the potential of using dextranase immobilized onto hydroxyapatite nanoparticles as a promising inorganic material. The optimal immobilization temperature, reaction time, and pH were determined to be 25 °C, 120 min, and pH 5, respectively. Dextranase could be loaded at 359.7 U/g. The immobilized dextranase was characterized by field emission gun-scanning electron microscope (FEG-SEM), X-ray diffraction (XRD), and Fourier-transformed infrared spectroscopy (FT-IR). The hydrolysis capacity of the immobilized enzyme was maintained at 71% at the 30th time of use. According to the constant temperature acceleration experiment, it was estimated that the immobilized dextranase could be stored for 99 days at 20 °C, indicating that the immobilized enzyme had good storage properties. Sodium chloride and sodium acetic did not desorb the immobilized dextranase. In contrast, dextranase was desorbed by sodium fluoride and sodium citrate. The hydrolysates were 79% oligosaccharides. The immobilized dextranase could significantly and thoroughly remove the dental plaque biofilm. Thus, immobilized dextranase has broad potential application in diverse fields in the future.

Engineering bioactive surfaces on nanoparticles and their biological interactions

The successful integration of nanoparticles into biomedical applications requires modulation of their surface properties so that the interaction with biological systems is regulated to minimize toxicity for biological function. In the present work, we have engineered bioactive surfaces on gold (Au) and silver (Ag) nanoparticles and subsequently evaluated their interaction with mouse skin fibroblasts and macrophages. The Au and Ag nanoparticles were synthesized using tyrosine, tryptophan, isonicotinylhydrazide, epigallocatechin gallate, and curcumin as reducing and stabilizing agents. The nanoparticles thus prepared showed surface corona and exhibited free radical scavenging and enzyme activities with limited cytotoxicity and genotoxicity. We have thus developed avenues for engineering the surface of nanoparticles for biological applications.

Polychemotherapy with Curcumin and Doxorubicin via Biological Nanoplatforms: Enhancing Antitumor Activity

Doxorubicin (DOX) is a well-known chemotherapeutic agent extensively applied in the field of cancer therapy. However, similar to other chemotherapeutic agents such as cisplatin, paclitaxel, docetaxel, etoposide and oxaliplatin, cancer cells are able to obtain chemoresistance that limits DOX efficacy. In respect to dose-dependent side effect of DOX, enhancing its dosage is not recommended for effective cancer chemotherapy. Therefore, different strategies have been considered for reversing DOX resistance and diminishing its side effects. Phytochemical are potential candidates in this case due to their great pharmacological activities. Curcumin is a potential antitumor phytochemical isolated from Curcuma longa with capacity of suppressing cancer metastasis and proliferation and affecting molecular pathways. Experiments have demonstrated the potential of curcumin for inhibiting chemoresistance by downregulating oncogene pathways such as MMP-2, TGF-β, EMT, PI3K/Akt, NF-κB and AP-1. Furthermore, coadministration of curcumin and DOX potentiates apoptosis induction in cancer cells. In light of this, nanoplatforms have been employed for codelivery of curcumin and DOX. This results in promoting the bioavailability and internalization of the aforementioned active compounds in cancer cells and, consequently, enhancing their antitumor activity. Noteworthy, curcumin has been applied for reducing adverse effects of DOX on normal cells and tissues via reducing inflammation, oxidative stress and apoptosis. The current review highlights the anticancer mechanism, side effects and codelivery of curcumin and DOX via nanovehicles.

Amino modified magnetic halloysite nanotube supporting chloroperoxidase immobilization: enhanced stability, reusability, and efficient degradation of pesticide residue in wastewater

Halloysite nanotube (HNT) is a natural bio-compatible and stable nanomaterial available in abundance at low-cost. In this work, HNT was modified by two strategies to make it suitable for supporting immobilization of chloroperoxidase (CPO). Firstly, Fe₃O₄ nanoparticles were deposited on HNT, so magnetic separation can be used instead of centrifugation. Then, the magnetic HNT was modified by 3-aminopropyltriethoxysilane (APTES), which can provide amine group on surface of HNT and meanwhile inhibit the agglomeration of magnetic HNT. Then, HNT-Fe₃O₄ -APTES was linked with branched polyethyleneimine (PEI) to provide more amino for binding with enzyme. The so-prepared CPO@HNT-Fe₃O₄-APTES-PEI showed enhanced enzyme loading, reusability, improved thermal stability and tolerance to organic solvents than free CPO. For example, after 10 repeated uses, CPO@HNT- Fe₃O₄-APTES-PEI can maintain 92.20% of its original activity compared with 65.12% of activity of CPO@HNT-APTES-PEI and 45.69% of activity of CPO@HNT. The kinetic parameters indicated the affinity and specificity of immobilized enzyme to substrate was increased. CPO@HNT-Fe₃O₄-APTES-PEI was very efficient when it was applied in the degradation of pesticides mesotrione in wastewater. The degradation efficiency can reach 90% within 20 min at range of 5-40 μmol·L^-1. These results ensure the potential practical application of this bio-materials in wastewater treatment.