Chemical binding of horseradish peroxidase enzyme with poly beta-cyclodextrin and its application as molecularly imprinted polymer for the monitoring of H2 O2 in human plasma samples

β-Cyclodextrin-Modified Laser-Induced Graphene Electrode for Detection of N6-Methyladenosine in RNA

Laser-induced graphene (LIG) possesses characteristics of easy handling, miniaturization, and unique electrical properties. We modified the surface of LIG by electropolymerizing β-cyclodextrin (β-CD), which was used to immobilize antibodies on the electrode surface for highly sensitive detection of targets. N6-methyladenosine (m6A) is the most prevalent reversible modification in mammalian messenger RNA and noncoding RNA, influencing the development of various cancers. Here, β-CD was electropolymerized to immobilize the anti-m6A antibody, which subsequently recognized the target m6A. This was integrated into the catalytic hydrogen peroxide-hydroquinone (H2O2-HQ) redox system using phos-tag-biotin to generate electrochemical signals from streptavidin-modified horseradish peroxidase (SA-HRP). Under optimal conditions, the biosensor exhibited a linear range from 0.1 to 100 nM with a minimum detection limit of 96 pM. The method was successfully applied to the recovery analysis of m6A from HeLa cells through spiking experiments and aims to inspire strategies for point-of-care testing (POCT).

Immobilization of horseradish peroxidase with zwitterionic polymer material for industrial phenolic removal

Horseradish peroxidase (HRP) is a hemoglobin composed of a single peptide chain that catalyzes the oxidation of various substrates such as phenol and aniline in the presence of hydrogen peroxide via its iron-porphyrin catalytic center. This enzyme is widely used in industrial phenol removal, food additives, biomedicine, and clinical test reagents due to its rapid reaction rate and obvious reaction outcomes. However, the large-scale use of HRP in industrial applications still faces numerous challenges, including activity, stability, and sustainability. This study demonstrates that when peroxidase is immobilized in zwitterionic polymer hydrogels, polycarboxybetaine (PCB) and polysulfobetaine (PSB), the properties of the enzyme are improved. PCB and PSB-embedded HRP exhibit a 6.11 and 1.53 times increase in Kcat/Km value, respectively, compared to the free enzyme. The immobilized enzyme also experiences increased activity over a range of temperatures and better tolerance to extreme pH and organic solvents, including formaldehyde. In addition, immobilized HRP exhibits excellent performance in storage and reproducibility. Remarkably, PCB-HRP still retains 80% of the initial activity after a 6-week storage period and can still attain the initial catalytic level of the free enzyme after six repeated cycles. It also removes 90% of phenol within 12 min, surpassing the current pharmacy on the market. These experimental results indicated that we have successfully designed a set of stable and efficient support substrates for horseradish peroxidase, which enhances its suitability for deployment in industrial applications.

Ultrasensitive Nonenzymatic Real-Time Hydrogen Peroxide Monitoring Using Gold Nanoparticle-Decorated Titanium Dioxide Nanotube Electrodes

An amperometric enzyme-free hydrogen peroxide (H₂O₂) sensor was developed by catalytically stabilizing active gold nanoparticles (Au NPs) of 4-5 nm on a porous titanium dioxide nanotube (TiO₂ NTs) electrode. The Au NPs were homogeneously distributed on anatase TiO₂ NTs with an outer diameter of ~102 nm, an inner diameter of ~60 nm, and a wall of thickness of ~40 nm. The cyclic voltammogram of the composite electrode showed a pair of redox peaks characterizing the electrocatalytic reduction of H₂O₂. The entrapping of Au NPs on TiO₂ NTs prevented aggregation and facilitated good electrical conductivity and electron transfer rate, thus generating a wide linear range, a low detection limit of ~104 nM, and high sensitivity of ~519 µA/mM, as well as excellent selectivity, reproducibility, repeatability, and stability over 60 days. Furthermore, excellent recovery and relative standard deviation (RSD) were achieved in real samples, which were tap water, milk, and Lactobacillus plantarum bacteria, thereby verifying the accuracy and potentiality of the developed nonenzymatic sensor.

Solid Phase-Based Microextraction Techniques in Therapeutic Drug Monitoring

Therapeutic drug monitoring is an established practice for a small group of drugs, particularly those presenting narrow therapeutic windows, for which there is a direct relationship between concentration and pharmacological effects at the site of action. Drug concentrations in biological fluids are used, in addition to other clinical observation measures, to assess the patient's status, since they are the support for therapy individualization and allow assessing adherence to therapy. Monitoring these drug classes is of great importance, as it minimizes the risk of medical interactions, as well as toxic effects. In addition, the quantification of these drugs through routine toxicological tests and the development of new monitoring methodologies are extremely relevant for public health and for the well-being of the patient, and it has implications in clinical and forensic situations. In this sense, the use of new extraction procedures that employ smaller volumes of sample and organic solvents, therefore considered miniaturized and green techniques, is of great interest in this field. From these, the use of fabric-phase extractions seems appealing. Noteworthy is the fact that SPME, which was the first of these miniaturized approaches to be used in the early '90s, is still the most used solventless procedure, providing solid and sound results. The main goal of this paper is to perform a critical review of sample preparation techniques based on solid-phase microextraction for drug detection in therapeutic monitoring situations.

Biological oxidation methods for the removal of organic and inorganic contaminants from wastewater: A comprehensive review

Enzyme-based bioremediation is a simple, cost-effective, and environmentally friendly method for isolating and removing a wide range of environmental pollutants. This study is a comprehensive review of recent studies on the oxidation of pollutants by biological oxidation methods, performed individually or in combination with other methods. The main bio-oxidants capable of removing all types of pollutants, such as organic and inorganic molecules, from fungi, bacteria, algae, and plants, and different types of enzymes, as well as the removal mechanisms, were investigated. The use of mediators and modification methods to improve the performance of microorganisms and their resistance under harsh real wastewater conditions was discussed, and numerous case studies were presented and compared. The advantages and disadvantages of conventional and novel immobilization methods, and the development of enzyme engineering to adjust the content and properties of the desired enzymes, were also explained. The optimal operating parameters such as temperature and pH, which usually lead to the best performance, were presented. A detailed overview of the different combination processes was also given, including bio-oxidation in coincident or consecutive combination with adsorption, advanced oxidation processes, and membrane separation. One of the most important issues that this study has addressed is the removal of both organic and inorganic contaminants, taking into account the actual wastewaters and the economic aspect.

Enzymatic recognition of hydrogen peroxide (H2 O2 ) in human plasma samples using HRP immobilized on the surface of poly(arginine-toluidine blue)- Fe3 O4 nanoparticles modified polydopamine; A novel biosensor

In this study, an innovative strategy was proposed for the electrocatalytical reduction and enzymatic biosensing of hydrogen peroxide (H₂ O₂ ) using chronoamperometry technique. For the first time, immobilization of horseradish peroxidase (HRP) in polydopamine-modified magnetic nanoparticles (PDA-MNPs) was successfully performed. Also, poly(l-arginine/toluidine blue) film-modified glassy carbon electrode was constructed through co-electropolymerization of l-arginine and toluidine blue on the surface of GCE using cyclic voltammetry technique. The engineered hybrid thin film provides strong functionalities for efficient grafting of PDA-MNPs which, in turn, enable the covalent immobilization of HRP. The proposed biosensor was used for the detection of H₂ O₂ in the range of 0.5-30 μM with a low limit of quantification 0.23 μM. It also was successfully applied for the investigation of hydrogen peroxide in human plasma samples.

Green Aspects in Molecularly Imprinted Polymers by Biomass Waste Utilization

Molecular Imprinting Polymer (MIP) technology is a technique to design artificial receptors with a predetermined selectivity and specificity for a given analyte, which can be used as ideal materials in various application fields. In the last decades, MIP technology has gained much attention from the scientific world as summarized in several reviews with this topic. Furthermore, green synthesis in chemistry is nowadays one of the essential aspects to be taken into consideration in the development of novel products. In accordance with this feature, the MIP community more recently devoted considerable research and development efforts on eco-friendly processes. Among other materials, biomass waste, which is a big environmental problem because most of it is discarded, can represent a potential sustainable alternative source in green synthesis, which can be addressed to the production of high-value carbon-based materials with different applications. This review aims to focus and explore in detail the recent progress in the use of biomass waste for imprinted polymers preparation. Specifically, different types of biomass waste in MIP preparation will be exploited: chitosan, cellulose, activated carbon, carbon dots, cyclodextrins, and waste extracts, describing the approaches used in the synthesis of MIPs combined with biomass waste derivatives.

Chemical binding of molecular-imprinted polymer to biotinilated antibody: Utilization of molecular imprinting polymer as intelligent synthetic biomaterials toward recognition of carcinoma embryonic antigen in human plasma sample

In this study, a novel biosensor based on molecular imprinting polymer (MIP) methodology was fabricated toward recognition of carcinoembryonic antigen (CEA). For this purpose, poly (toluidine blue) (PTB) was electropolymerized on the surface of gold electrode in the absence and presence of CEA. So, the target molecules were entrapped into the imprinted specific cavities of MIP. Obtained results show that, the binding affinity of the MIP system was significantly higher than that of revealed for the nonimprinted polymer (NIP) system, MIP-based biosensor revealed linear response from (0.005 to 75 μg/L) and low limit of quantification of (0.005 μg/L) by using chronoamperometry technique, leading to CEA monitoring in real and clinical samples. Thus, a novel technique for rapid, simple, sensitive and affordable monitoring of CEA (LLOQ = 0.005 μg/L) has provided through developed biosensor. From a future perspective, moreover, this method can be considered as an applicable candidate in biomedical and clinical analysis for point-of-care usages.