Regular ArticleA Method for the High Efficiency of Water-Soluble Carbodiimide-Mediated Amidation
Abstract
Water-soluble carbodiimides are widely used for carboxyl-amine conjugation. However, extremely variable and low yields, obtained under a variety of conditions, have been a serious problem in the coupling. A simple method, optimizing various parameters of the coupling reaction, in which N-hydroxysuccinimide is included to assist the 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride-catalyzed amidation reaction is described. A product yield of up to 90% is routinely achieved.
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Smart stimuli-responsive hydrogels for drug delivery in periodontitis treatment
2023, Biomedicine and PharmacotherapyPeriodontitis is a chronic inflammatory disease initiated by pathogenic biofilms and host immunity that damages tooth-supporting tissues, including the gingiva, periodontal ligament and alveolar bone. The physiological functions of the oral cavity, such as saliva secretion and chewing, greatly reduce the residence of therapeutic drugs in the area of a periodontal lesion. In addition, complex and diverse pathogenic mechanisms make effectively treating periodontitis difficult. Therefore, designing advanced local drug delivery systems and rational therapeutic strategies are the basis for successful periodontitis treatment. Hydrogels have attracted considerable interest in the field of periodontitis treatment due to their biocompatibility, biodegradability and convenient administration to the periodontal pocket. In recent years, the focus of hydrogel research has shifted to smart stimuli-responsive hydrogels, which can undergo flexible sol-gel transitions in situ and control drug release in response to stimulation by temperature, light, pH, ROS, glucose, or enzymes. In this review, we systematically introduce the development and rational design of emerging smart stimuli-responsive hydrogels for periodontitis treatment. We also discuss the state-of-the-art therapeutic strategies of smart hydrogels based on the pathogenesis of periodontitis. Additionally, the challenges and future research directions of smart hydrogels for periodontitis treatment are discussed from the perspective of developing efficient hydrogel delivery systems and potential clinical applications.
Anchored ferrocene based heterogeneous electrocatalyst for the synthesis of benzimidazoles
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Laccase mediated electrosynthesis of heliotropin on mango-kernel derived carbon nanosphere composite: A sustainable approach
2022, Journal of Science: Advanced Materials and DevicesFacile fabrication of enzyme immobilized carbon nanospheres (CNS) based catalysts with high electrical conductivity and catalytic efficiency are of decisive importance for their electrocatalysis. A novel, green and highly efficient synthesis route is reported here for the development of an electrode surface with enhanced electrical conductivity and better catalytic activity for the electrochemical synthesis of heliotropin. The obtained biowaste (mango seed kernels) was pyrolyzed and subjected to acid treatment to form functionalized CNS (f-CNS). The functionalized carbon fiber paper (CFP) electrode was employed as a template for laccase immobilization which was further treated with free laccase resulting in the formation of Lac-fCNS/CFP electrode. The developed electrode exhibited excellent electrooxidation of piperonyl alcohol in the presence of 2,2,6,6-Tetramethyl-1-piperidinyloxy (TEMPO), which served as a mediator. A high yield (78%) of heliotropin was achieved during the electrooxidation at 0.78 V via bulk electrolysis. The obtained product (heliotropin aka piperonal) was confirmed via 1H NMR and 13C NMR. Additionally, computational molecular docking analysis of f-CNS:laccase composite showed strong binding affinity (−6.2 kcal/mol) with TEMPO in comparison with free laccase (−5.1 kcal/mol). The excellent selectivity and efficiency of the developed electrocatalyst aim to surpass all other reported laccase-TEMPO mediated based electrocatalytic oxidation reactions.
Characterisation of products from EDC-mediated PEG substitution of chitosan allows optimisation of reaction conditions
2022, International Journal of Biological MacromoleculesPEGylation is a common method use to modify the physiochemical properties and increase the solubility of chitosan (CHI). Knowledge of optimal reaction conditions for PEGylation of CHI underpins its ongoing use in nanomedicine. This study synthesised methoxy polyethyleneglycol grafted CHI (mPEG-CHI) using carbodiimide-mediated coupling. The effect of reagent concentrations and pH on the degree of substitution (DS) and the PEGylation yield (conversion of free PEG to conjugated PEG) was evaluated through detailed chemical characterisation. Within the parameter space investigated, optimised reaction conditions (NH2: COOH:NHS:EDC of 3.5:1:1:10, pH = 5) resulted in a DS of 24 % and a PEGylation yield of 84 %. An EDC-derived adduct formed at pH ≥ 5.5 and at a 15-fold excess of EDC relative to COOH. The adduct was evaluated to be a guanidine derivative formed by the reaction of the amine group of CHI directly with EDC. DS ≥ 12 % imparted water solubility to CHI at physiological pH and mPEG-CHI (0.2–1.0 mg/mL) was not cytotoxic against the breast cancer cell lines MCF-7 and MDA-MB-231, indicating its suitability for medical applications.
SARS-CoV-2 electrochemical immunosensor based on the spike-ACE2 complex
2022, Analytica Chimica ActaRapid, straightforward, and massive diagnosis of coronavirus disease 2019 (COVID-19) is one of the more important measures to mitigate the current pandemics. This work reports on an immunosensor to rapidly detect the spike protein from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The immunosensing device entraps the spike protein linked to angiotensin-converting enzyme host receptor (ACE2) protein in a sandwich between carboxylated magnetic beads functionalized with an anti-spike antibody and an anti-ACE2 antibody, further labeled with streptavidin (poly)horseradish peroxidase (HRP) reporter enzyme. The particles were confined at the surface of screen-printed gold electrodes, whose signal resulting from the interaction of the enzyme with a mediator was recorded in a portable potentiostat. The immunosensor showed a sensitivity of 0.83 μA∗mL/μg and a limit of detection of 22.5 ng/mL of spike protein, with high reproducibility. As a proof-of-concept, it detected commercial spike protein-supplemented buffer solutions, pseudovirions, isolated viral particles and ten nasopharyngeal swab samples from infected patients compared to samples from three healthy individuals paving the way to detect the virus closer to the patient.
Crosslinkers for polysaccharides and proteins: Synthesis conditions, mechanisms, and crosslinking efficiency, a review
2022, International Journal of Biological MacromoleculesPolysaccharides and proteins are important macromolecules for developing hydrogels devoted to biomedical applications. Chemical hydrogels offer chemical, mechanical, and dimensional stability than physical hydrogels due to the chemical bonds among the chains mediated by crosslinkers. There are many crosslinkers to synthesize polysaccharides and proteins based on hydrogels. In this review, we revisited the crosslinking reaction mechanisms between synthetic or natural crosslinkers and polysaccharides or proteins. The selected synthetic crosslinkers were glutaraldehyde, carbodiimide, boric acid, sodium trimetaphosphate, N,N′-methylene bisacrylamide, and polycarboxylic acid, whereas the selected natural crosslinkers included transglutaminase, tyrosinase, horseradish peroxidase, laccase, sortase A, genipin, vanillin, tannic acid, and phytic acid. No less important are the reactions involving click chemistry and the macromolecular crosslinkers for polysaccharides and proteins. Literature examples of polysaccharides or proteins crosslinked by the different strategies were presented along with the corresponding highlights. The general mechanism involved in chemical crosslinking mediated by gamma and UV radiation was discussed, with particular attention to materials commonly used in digital light processing. The evaluation of crosslinking efficiency by gravimetric measurements, rheology, and spectroscopic techniques was presented. Finally, we presented the challenges and opportunities to create safe chemical hydrogels for biomedical applications.