Rapid Screening of Lipase Inhibitors in Scutellaria baicalensis by Using Porcine Pancreatic Lipase Immobilized on Magnetic Core–Shell Metal–Organic Frameworks

Immobilization of pancreatin based on ultrasound-assisted polydopamine functionalized magnetic porous chitosan for the detoxification of ochratoxin A in wine

Ochratoxin A (OTA) is a mycotoxin that globally contaminates fruits and their products. Since OTA have a huge negative impact on health hazards and economic losses, it is imperative to establish an effective and safe strategy for detoxification. Here, pancreatin was immobilized on the surface of polydopamine functionalized magnetic porous chitosan (MPCTS@ PDA) for the degradation of OTA. Compared with free pancreatin, MPCTS@ PDA@ pancreatin displayed excellent thermal stability, acid resistance, storage stability and OTA detoxification in wine (>58%). Moreover, the MPCTS@ PDA@ pancreatin retained 43% initial activity after 8 reuse cycles. There was no significant change in the quality of wine after MPCTS@ PDA@ pancreatin treatment. Moreover, it did not exhibit cytotoxicity which facilitated its application in wine. These results demonstrated that MPCTS@ PDA@ pancreatin can be used as a highly effective biocatalysate for OTA detoxification in wine.

Carboxy-Functionalized Covalent Organic Framework as a Carrier for Lipase Immobilization and Its Application in Inhibitors Screening

Covalent organic frameworks (COFs) with large specific surface areas, high porosity, good stability, and designable structure are promising carriers for immobilized enzymes. It is important to explore lipase inhibitors from natural foods as lipase inhibitors are closely related to the treatment of obesity. In this work, a carboxyl functionalized covalent organic framework (TpBD-3COOH) was prepared by solvothermal method for covalent immobilization of porcine pancreatic lipase (PPL) and obtained the enzyme-decorated COF (PPL@COF). The immobilized lipase showed wider pH and temperature tolerance with the same optimal pH and temperature of 7.5 and 50 ℃ compared to free lipase. After 6 successive reuses, the PPL@COF maintained 53.0% of its original activity. Immobilized lipase also displayed enhanced storage stability (55.4% after 14 days at 4 ℃). When p-nitrophenyl acetate was applied as the substrate, the calculated Michaelis constant was 3.57 mM and the half maximal inhibitory concentration of orlistat was 3.20 μM. Finally, the PPL@COF was used for enzyme inhibitors screening from natural foods combined with UV spectrophotometry, and Hawthorn was screened for excellent lipase inhibitory activity.

Novel biocatalysts based on enzymes in complexes with nano- and micromaterials

In today's world, there is a wide array of materials engineered at the nano- and microscale, with numerous applications attributed to these innovations. This review aims to provide a concise overview of how nano- and micromaterials are utilized for enzyme immobilization. Enzymes act as eco-friendly biocatalysts extensively used in various industries and medicine. However, their widespread adoption faces challenges due to factors such as enzyme instability under different conditions, resulting in reduced effectiveness, high costs, and limited reusability. To address these issues, researchers have explored immobilization techniques using nano- and microscale materials as a potential solution. Such techniques offer the promise of enhancing enzyme stability against varying temperatures, solvents, pH levels, pollutants, and impurities. Consequently, enzyme immobilization remains a subject of great interest within both the scientific community and the industrial sector. As of now, the primary goal of enzyme immobilization is not solely limited to enabling reusability and stability. It has been demonstrated as a powerful tool to enhance various enzyme properties and improve biocatalyst performance and characteristics. The integration of nano- and microscale materials into biomedical devices is seamless, given the similarity in size to most biological systems. Common materials employed in developing these nanotechnology products include synthetic polymers, carbon-based nanomaterials, magnetic micro- and nanoparticles, metal and metal oxide nanoparticles, metal-organic frameworks, nano-sized mesoporous hydrogen-bonded organic frameworks, protein-based nano-delivery systems, lipid-based nano- and micromaterials, and polysaccharide-based nanoparticles.

The synthesis and functionalization of metal organic frameworks and their applications for the selective separation of proteins/peptides

Recently, proteins separation has drawn great interest for the full investigation of a proteome because the proteins separation is the precondition when conducting clinical research or proteomics research. Metal organic frameworks (MOFs) are fabricated via covalent connection between organic ligands and metal ions/clusters units. MOFs have attracted much attention due to the ultra-high specific surface area, tunable structure, more metal site or unsaturated site, and chemical stability. Over the past decade, different functionalization types of MOFs have been reported in combination with amino acids, nucleic acids, proteins, polymers, and nanoparticles for various applications. In this review, the synthesis and functionalization of MOFs have been thoroughly discussed, and we introduced the existing problems and development trends in these fields. Furthermore, MOFs as advanced adsorbents for selective separation of proteins/peptides are summarized. Additionally, we present a comprehensive prospects and challenges in the preparation of robust functional MOFs-based adsorbents and make a final outlook on their future development prospects in selective separation of proteins/peptides.

A rationally engineered specific near-infrared fluorogenic substrate of human pancreatic lipase for functional imaging and inhibitor screening

Obesity, now widespread all over the world, is frequently associated with several chronic diseases. Human pancreatic lipase (hPL) is a crucial digestive enzyme responsible for the digestion of dietary lipids in humans, and the inhibition of hPL is effective in reducing triglyceride intake and thus preventing and treating obesity. In this work, a practical sequential screening strategy was developed to construct a highly selective near-infrared fluorogenic substrate 7-STCFC for hPL. Under physiological conditions, 7-STCFC can be rapidly hydrolyzed by hPL to form 7-HTCFC, which triggers 254-fold NIR signal enhancement at 670 nm. 7-STCFC was successfully applied for the sensing and imaging of endogenous PL in living systems (including living cells, tissues and organs) with low cytotoxicity and high imaging resolution. Moreover, a high-throughput screening platform was established using 7-STCFC, and the inhibitory effects of 94 kinds of herbs toward hPL were evaluated. Among them, Pu-erh tea stood out with outstanding hPL inhibitory effects, and the inhibitory ingredients and involved inhibitory mechanism were further revealed, which strongly facilitates the discovery of novel anti-obesity agents targeting hPL. Collectively, these findings suggested that our strategy was practical to develop an isoform-specific fluorogenic substrate for a target enzyme, and 7-STCFC was a powerful tool for monitoring PL activity in complex biological systems with value for exploring physiological functions and rapid screening of inhibitors.

Magnetic metal-organic frameworks immobilized enzyme-based nano-biocatalytic systems for sustainable biotechnology

Nanobiocatalysts, in which enzyme molecules are integrated into/onto multifunctional materials, such as metal-organic frameworks (MOFs), have been fascinating and appeared as a new interface of nanobiocatalysis with multi-oriented applications. Among various nano-support matrices, functionalized MOFs with magnetic attributes have gained supreme interest as versatile nano-biocatalytic systems for organic bio-transformations. From the design (fabrication) to deployment (application), magnetic MOFs have manifested notable efficacy in manipulating the enzyme microenvironment for robust biocatalysis and thus assure requisite applications in several areas of enzyme engineering at large and nano-biocatalytic transformations, in particular. Magnetic MOFs-linked enzyme-based nano-biocatalytic systems offer chemo-regio- and stereo-selectivities, specificities, and resistivities under fine-tuned enzyme microenvironments. Considering the current sustainable bioprocesses demands and green chemistry needs, we reviewed synthesis chemistry and application prospects of magnetic MOFs-immobilized enzyme-based nano-biocatalytic systems for exploitability in different industrial and biotechnological sectors. More specifically, following a thorough introductory background, the first half of the review discusses various approaches to effectively developed magnetic MOFs. The second half mainly focuses on MOFs-assisted biocatalytic transformation applications, including biodegradation of phenolic compounds, removal of endocrine disrupting compounds, dye decolorization, green biosynthesis of sweeteners, biodiesel production, detection of herbicides and screening of ligands and inhibitors.

Functional Imaging and Inhibitor Screening of Human Pancreatic Lipase by a Resorufin-Based Fluorescent Probe

Human pancreatic lipase (hPL) is a crucial digestive enzyme responsible for the digestion of dietary lipids in humans, and inhibition of hPL is effective in reducing triglyceride intake, thereby preventing and treating obesity. In this study, a series of fatty acids with different carbon chain lengths were constructed to the fluorophore resorufin based on the substrate preference of hPL. Among them, RLE was found to have the best combination of stability, specificity, sensitivity and reactivity towards hPL. Under physiological conditions, RLE can be rapidly hydrolyzed by hPL and released to resorufin, which triggered approximately 100-fold fluorescence enhancement at 590 nm. RLE was successfully applied for sensing and imaging of endogenous PL in living systems with low cytotoxicity and high imaging resolution. Moreover, a visual high-throughput screening platform was established using RLE, and the inhibitory effects of hundreds of drugs and natural products toward hPL were evaluated. Collectively, this study reports a novel and highly specific enzyme-activatable fluorogenic substrate for hPL that could serve as a powerful tool for monitoring hPL activity in complex biological systems and showcases the potential to explore physiological functions and rapid screening of inhibitors.

Ultrathin Covalent Organic Framework Nanosheets/Ti3C2Tx-Based Photoelectrochemical Biosensor for Efficient Detection of Prostate-Specific Antigen

Designable and ultrathin covalent organic framework nanosheets (CONs) with good photoelectric activity are promising candidates for the construction of photoelectrochemical (PEC) biosensors for the detection of low-abundance biological substrates. However, achieving highly sensitive PEC properties by using emerging covalent organic framework nanosheets (CONs) remains a great challenge due to the polymeric nature and poor photoelectric activity of CONs. Herein, we report for the first time the preparation of novel composites and their PEC sensing properties by electrostatic self-assembly of ultrathin CONs (called TTPA-CONs) with Ti₃C₂T_x. The prepared TTPA-CONs/Ti₃C₂T_x composites can be used as photocathodes for PEC detection of prostate-specific antigen (PSA) with high sensitivity, low detection limit, and good stability. This work not only expands the application of CONs but also opens new avenues for the development of efficient PEC sensing platforms.