Design of amino-functionalized hollow mesoporous silica cube for enzyme immobilization and its application in synthesis of phosphatidylserine

Determination of free fatty acids in edible oil based on hollow mesoporous silica nanoparticles

In our study, ammoniated hollow mesoporous silica nanoparticles (NH2-HMSN) with uniform diameter and stable structure were successively prepared via SiO2 core hard template method. Fourier transformed infrared spectroscopy revealed that amino group was effectively modified. Adsorption experiments showed that adsorption capacity of NH2-HMSN towards free fatty acids (FFAs) was superior to aminated mesopores or silica microspheres. Following through optimization of extraction conditions, FFAs from edible oil samples were successfully gathered by NH2-HMSN and showed favorable linearities (0.2-90 μg g-1), remarkably low limit of detections (0.03-0.15 nmol g-1), acceptable recoveries (85.08-96.82 %) and relatively accurate precisions (1.64-4.99 %). In comparison to existing adsorbent, NH2-HMSN could be successfully prepared via the chemical reaction of common raw materials under normal pressure and temperature. Furthermore, NH2-HMSN with hollow and mesoporous structure was more effective than the current adsorbents aimed at FFAs analysis in aspect of surface area and adsorption capacity.

Whole-Cell Display of Phospholipase D in Escherichia coli for High-Efficiency Extracellular Phosphatidylserine Production

Phospholipids are widely utilized in various industries, including food, medicine, and cosmetics, due to their unique chemical properties and healthcare benefits. Phospholipase D (PLD) plays a crucial role in the biotransformation of phospholipids. Here, we have constructed a super-folder green fluorescent protein (sfGFP)-based phospholipase D (PLD) expression and surface-display system in Escherichia coli, enabling the surface display of sfGFP-PLDr34 on the bacteria. The displayed sfGFP-PLDr34 showed maximum enzymatic activity at pH 5.0 and 45 °C. The optimum Ca2+ concentrations for the transphosphatidylation activity and hydrolysis activity are 100 mM and 10 mM, respectively. The use of displayed sfGFP-PLDr34 for the conversion of phosphatidylcholine (PC) and L-serine to phosphatidylserine (PS) showed that nearly all the PC was converted into PS at the optimum conditions. The displayed enzyme can be reused for up to three rounds while still producing detectable levels of PS. Thus, Escherichia coli/sfGFP-PLD shows potential for the feasible industrial-scale production of PS. Moreover, this system is particularly valuable for quickly screening higher-activity PLDs. The fluorescence of sfGFP can indicate the expression level of the fused PLD and changes that occur during reuse.

Phospholipase D Immobilization on Lignin Nanoparticles for Enzymatic Transformation of Phospholipids

Lignin nanoparticles (LNPs) are promising components for various materials, given their controllable particle size and spherical shape. However, their origin from supramolecular aggregation has limited the applicability of LNPs as recoverable templates for immobilization of enzymes. In this study, we show that stabilized LNPs are highly promising for the immobilization of phospholipase D (PLD), the enzyme involved in the biocatalytic production of high-value polar head modified phospholipids of commercial interest, phosphatidylglycerol, phosphatidylserine and phosphatidylethanolamine. Starting from hydroxymethylated lignin, LNPs were prepared and successively hydrothermally treated to obtain c-HLNPs with high resistance to organic solvents and a wide range of pH values, covering the conditions for enzymatic reactions and enzyme recovery. The immobilization of PLD on c-HLNPs (PLD-c-HLNPs) was achieved through direct adsorption. We then successfully exploited this new enzymatic preparation in the preparation of pure polar head modified phospholipids with high yields (60-90 %). Furthermore, the high stability of PLD-c-HLNPs allows recycling for a number of reactions with appreciable maintenance of its catalytic activity. Thus, PLD-c-HLNPs can be regarded as a new, chemically stable, recyclable and user-friendly biocatalyst, based on a biobased inexpensive scaffold, to be employed in sustainable chemical processes for synthesis of value-added phospholipids.

Silica-based Nanoparticles for Enzyme Immobilization and Delivery

Enzymes play an indispensable role in biosystems, catalyzing a variety of chemical and biochemical reactions with exceptionally high efficiency and selectivity. These features render them uniquely positioned in developing novel catalytic systems and therapeutics. However, their practical application is largely hindered by the vulnerability, low reusability and the inability to overcome the biological barriers of enzymes. Silica-based nanoparticles (SNPs) are a classic family of nanomaterials with tunable physicochemical properties, making them ideal candidates to address the intrinsic shortcomings of natural enzymes. SNPs not only improve the activity and durability of enzymes, but also provide precise spatiotemporal control over their intracellular as well as systemic biodistributions for boosting the catalytic outcome. Herein, the recent progress in SNPs for enzyme immobilization and delivery is summarized. The therapeutic applications, including cancer therapy and bacterial inhibition, are particularly highlighted. Our perspectives in this field, including current challenges and possible future research directions are also provided.

Synthesis of two novel bio-based hydrogels using sodium alginate and chitosan and their proficiency in physical immobilization of enzymes

Herein, four novel and bio-based hydrogel samples using sodium alginate (SA) and chitosan (CH) grafted with acrylamide (AAm) and glycidyl methacrylate (GMA) and their reinforced nanocomposites with graphene oxide (GO) were synthesized and coded as SA-g-(AAm-co-GMA), CH-g-(AAm-co-GMA), GO/SA-g-(AAm-co-GMA), and GO/CH-g-(AAm-co-GMA), respectively. The morphology, net charge, and water absorption capacity of samples were entirely changed by switching the biopolymer from SA to CH and adding a nano-filler. The proficiencies of hydrogels were compared in the immobilization of a model metagenomic-derived xylanase (PersiXyn9). The best performance was observed for GO/SA-g-poly(AAm-co-GMA) sample indicating better stabilizing electrostatic attractions between PersiXyn9 and reinforced SA-based hydrogel. Compared to the free enzyme, the immobilized PersiXyn9 on reinforced SA-based hydrogel showed a 110.1% increase in the released reducing sugar and almost double relative activity after 180 min storage. While immobilized enzyme on SA-based hydrogel displayed 58.7% activity after twelve reuse cycles, the enzyme on CH-based carrier just retained 8.5% activity after similar runs.

Advances in the application of nanotechnology in reducing cardiotoxicity induced by cancer chemotherapy

Advances in the development of anti-tumour drugs and related technologies have resulted in a significant increase in the number of cancer survivors. However, the incidence of chemotherapy-induced cardiotoxicity (CIC) has been rising continuously, threatening their long-term survival. The integration of nanotechnology and biomedicine has brought about an unprecedented technological revolution and has promoted the progress of anti-tumour therapy. In this review, we summarised the possible mechanisms of CIC, evaluated the role of nanoparticles (including liposomes, polymeric micelles, dendrimers, and hydrogels) as drug carriers in preventing cardiotoxicity and proposed five advantages of nanotechnology in reducing cardiotoxicity: Liposomes cannot easily penetrate the heart's endothelial barrier; optimized delivery strategies reduce distribution in important organs, such as the heart; targeting the tumour microenvironment and niche; stimulus-responsive polymer nano-drug carriers rapidly iterate; better economic benefits were obtained. Nanoparticles can effectively deliver chemotherapeutic drugs to tumour tissues, while reducing the toxicity to heart tissues, and break through the dilemma of existing chemotherapy to a certain extent. It is important to explore the interactions between the physicochemical properties of nanoparticles and optimize the highly specific tumour targeting strategy in the future.