Dual enzymes-mimic activity of nanolayered manganese-calcium oxide for fluorometric determination of metformin

A sensitive and selective amperometric determination of perfluorooctanesulfonic acid on Mo2Ti2AlC3 MXene precursor-modified electrode

Various commercial and industrial products widely use highly toxic eight-carbon-chain perfluorooctanesulfonate (PFOS), posing a significant threat to the health of living organisms. In this study, the electrochemical detection of PFOS was achieved by developing a carbon paste electrode (CPE) using the Mo2Ti2AlC3 MAX phase. Mo2Ti2AlC3 was synthesized and directly used to construct the CPE. The electrochemical performance of the prepared sensor was tested using various electrochemical techniques, such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), differential pulse voltammetry (DPV), and amperometric titration. The developed electrochemical sensor exhibited two linear ranges from 0.001 to 0.09 μM and from 1.1 to 62.6 μM, with a detection limit of 0.04 nM. The sensor demonstrated high sensitivity, measuring 145.1 μA μM-1 cm-2, and a response time of 5 s for PFOS quantification at a working potential of 0.3 V. Additionally, the sensor demonstrated outstanding resistance to typical interfering chemicals. The applicability and reliability of the developed sensor for PFOS determination were further tested in real samples, yielding recoveries in the range of 92.6-108.2%, with relative standard deviation (RSD) values between 1.8% and 3.7%. The Mo2Ti2AlC3 MAX phase-based electrochemical sensor is simple, rapid, sensitive, and cost-effective, making it a promising approach for the quantification of PFOS in environmental water and soil samples.

Bioinspired construction of ATP/Co-Al-Zn LDH nanozyme with enhanced peroxidase-mimic performance for efficient bactericidal activity through membrane disruption

In recent years, overuse of antibiotics has led to emerging antibiotic-resistant strains of bacteria. Consequently, creating new, highly productive antibacterial agents is crucial. In this work, we synthesized copper-aluminum-zinc layered double hydroxide (Co-Al-Zn LDH) and modified it using adenosine triphosphate. After characterization, the enzyme-like activity of the prepared particles was evaluated. The results indicated peroxidase-mimic performance of ATP/Co-Al-Zn LDH with Km values of 0.38 mM and 1.69 mM for TMB (3,3',5,5'-tetramethylbenzidine) and hydrogen peroxide (H2O2), respectively, which were lower than that of horseradish peroxidase. The highest peroxidase-like activity of ATP/Co-Al-Zn LDH was achieved at 20 °C, pH 4, with a 1.02 mg/mL catalyst, 231 μM TMB, and 1.9 mM H2O2. The bactericidal activity of the developed nanozyme was studied against E. coli and S. aureus. The peroxidase-mimic nanozyme decomposes H2O2 and generates free radicals to kill bacteria in vitro. The minimum inhibitory concentration (MIC) of ATP/Co-Al-Zn LDH was 15 μg/mL and 20 μg/mL for S. aureus and E. coli, respectively. The morphological characteristics of the nanozyme-treated bacterial cells showed dramatic changes in bacterial morphology. Our results revealed higher antibacterial activity of ATP/Co-Al-Zn LDH against S. aureus. Therefore, the developed nanozyme could serve as a substitute for conventional antibiotics.

Implications of analytical nanoscience in pharmaceutical and biomedical fields: A critical view

This review summarizes recent progress performed in the design and application of analytical tools and methodologies using nanomaterials for pharmaceutical analysis, and specifically new nanomedicines at distinct phases of development and translation from preclinical to clinical stages. Over the last 10-15 years, a growing number of studies have utilized various nanomaterials, including carbon-based, metallic nanoparticles, polymeric nanomaterials, materials based on biological molecules, and composite nanomaterials as tools for improving the analysis of pharmaceutical products. New and more complex nanomaterials are currently being explored to influence different stages of the analytical process. These materials provide unique properties to support the extraction of analytes in complex samples, increase the selectivity and efficiency of chromatographic separations, and improve the analytical properties of many sensor applications. Indeed, nanomaterials, including electrochemical detection approaches and biosensing, are expanding at a remarkable rate. Furthermore, the analytical performance of numerous approaches to determine drugs in different matrices can be significantly improved in terms of precision, detection limits, selectivity, and time of analysis. However, the quality control and metrological characterization of the currently synthesized nanomaterials still depend on the development of new and improved analytical methodologies, and the application of specific and improved instrumentation. Therefore, there is still much to explore about the properties of nanomaterials which need to be determined even more precisely and accurately.

Design and application of histidine-functionalized ZnCr-LDH nanozyme for promoting bacteria-infected wound healing

Excessive use of antibiotics can lead to an increase in antibiotic-resistant bacteria, which makes it a serious health threat. Therefore, developing new materials with antibacterial activity, such as nanozymes, has gained considerable attention. Reactive oxygen species (ROS) produced by nanozymes have rapid and effective antibacterial efficacy. Here, histidine (His) modified ZnCr layered double hydroxide (LDH) was synthesized inspired by the natural enzyme, and the enzyme-like activity of His/ZnCr-LDH was tested using a colorimetric method. Then, we developed an acid-enhanced antibacterial method based on the high peroxidase-like activity of His/ZnCr-LDH, and its ROS-generating capability in the presence of glucose oxidase (GOx) and glucose (Glu) as a source of hydrogen peroxide (H2O2). Gluconic acid (GA), the main product of the GOx reaction, provides an acidic environment and promotes ROS generation. The mentioned strategy shows high antibacterial activity at a low minimum inhibitory concentration (MIC) which represents the potential of His/ZnCr-LDH for effective bacterial elimination (3.5 μg mL-1 for S. aureus and 6 μg mL-1 for E. coli). In addition, animal experiments illustrated that the His/ZnCr-LDH can successfully boost the curing of infected wounds. The outcomes indicate that amino acid modified LDHs offer a new strategy for effective bacterial removal in different medical applications.

A robust and facile label-free method for highly sensitive colorimetric detection of ascorbic acid in fresh fruits based on peroxidase-like activity of modified FeCo-LDH@WO3 nanocomposite

Many compounds such as amino acids and oligonucleotides have been shown to effectively change peroxidase-like activity of nanoparticles. While a few studies have focused on mimicking the active site of natural enzymes on nanozymes and thus increasing their substrate affinity. Therefore, in this work, the surface of FeCo@WO3 nanocomposite was modified using guanosine triphosphate (GTP) to mimic the histidine of peroxidase enzyme's active site and its modification was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FT-IR). Then, the peroxidase-mimicking activity of the modified nanocomposite was tested using a colorimetric method, based on the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2). It was found that GTP improves the activity of FeCo@WO3 as a natural peroxidase active site's distal histidine residue. Ascorbic acid (AA) is a powerful antioxidant that induces the reduction of blue color (oxidized TMB) ox-TMB to colorless TMB. The colorimetric method was applied for the sensitive detection of AA in common fruits. The linear range of AA was 10-100 μM with a limit of detection (LOD) of 0.27 μM, which provides a rapid and sensitive method for testing AA in the field of food analysis.

Metal-organic framework (MOF)-derived flower-like Ni-MOF@NiV-layered double hydroxides as peroxidase mimetics for colorimetric detection of hydroquinone

BACKGROUND

Nanozymes are one of the ideal substitutes for natural enzymes because of their excellent chemical stability and simple preparation methods. However, due to the limited catalytic ability of most reported nanozymes, constructing nanomaterials with low cost and high activity is gradually becoming an exploration focus in the field of nanozymes. Heteroatom doping of metal-organic frameworks is one of potential approaches to design nanozymes with high catalytic performance. Due to their multiple valence states properties, V-doped metal-organic framework (MOF)-derived LDH is expected to be a good enzyme-like catalyst. To our knowledge, the V-doped MOF-derived LDH as nanozyme is not explored before.

RESULTS

We report the in-situ synthesis of NiV-layered double hydroxides (LDHs) on nickel-based MOF, i.e. Ni-MOF@NiV-LDHs. The MOF surface is covered by 2D nanosheets. This unique structural design increases the specific surface area of the material, enables more exposure of catalytic active sites to participate in reactions and accelerates the electron transfer rate. The Ni-MOF@NiV-LDHs have high peroxidase-like activity able to catalyze TMB oxidation by H2O2 via the generation of •OH and O2•-. Relative to Ni-MOF, the Ni-MOF@NiV-LDHs shows 47-fold peroxidase-like activity rise. It had good affinity to TMB and H2O2, with the Michaelis-Menten constants of 0.12 mM and 0.007 mM, respectively. The hydroquinone (HQ) consumed the reactive oxygen species generated in the TMB + H2O2+Ni-MOF@NiV-LDHs system to inhibit the TMB oxidation. On this basis, a sensitive and rapid assay for determining HQ was developed, with a linear range of 0.50-70 μM and a LOD of 0.37 μM.

SIGNIFICANCE

This work provided some clues for the further development of novel nanozymes with high catalytic performance via a strategy of heteroatom doping. And the constructed colorimetric analysis method was successfully utilized for the determination of HQ in actual waters, which has the potential for practical application in the analysis of environmental pollutants.

A dual-emission ratiometric fluorescent biosensor for ultrasensitive detection of glibenclamide using S-CDs/CdS quantum dots

In the present work, sulfide-doped carbon dots (S-CDs)/cadmium sulfide quantum dots (CdS QDs) ratiometric fluorescent nanosensor has been developed for sensitive and selective determination of glibenclamide (GLC) in biological fluids. The method was based on the quenching effect of GLC on the dual-emission intensity of the S-CDs/CdS QDs system at 420 nm and 650 nm, which are related to S-CDs and CdS QDs, respectively. The fluorimetric data analysis indicated that the fluorescence signals of the system were quenched by adding GLC in a concentration-dependent manner. A good linear relationship was observed between GLC concentration and the quenched fluorescence intensity of the S-CDs/CdS QDs in the range of 0.3 nM-10.0 μM. The limit of detection (LOD) value was estimated to be 0.12 nM. Furthermore, under optimum conditions, GLC was detected in spiked human serum sample (as real media) using the developed ratiometric nanosensor with an accuracy of 99.6%. According to the results, the developed dual-emission system can be used as a reliable method for the quantitative detection of GLC in biological samples.

Effect of Excipients on the Quality of Drug Formulation and Immediate Release of Generic Metformin HCl Tablets

Generic medications are bioequivalent to brand-name medications, but the quality and purity of generic medications are still debatable. The aim of this study was to compare the generic product of metformin (MET) to its branded counterpart using pure MET powder as a reference. Quality control tablet assessment and in vitro evaluation of drug release were carried out in various pH media. Additionally, several analytical methods and thermal techniques were used, namely differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), and confocal Raman microscopy. The results showed a significant difference between the two products. In terms of friability assessment, mean resistance force, and tablet disintegration, the generic MET product showed significant weight loss, higher mean resistance force, longer disintegration time, and a slower rate of drug release. In addition, DSC and TGA showed that the generic product had the lowest melting point and the least weight loss compared to the branded product and pure powder. XRD and SEM demonstrated some changes in the crystallinity structure of the molecule particles for the generic product. Additionally, FTIR and confocal Raman revealed the same peaks and band shifts in all samples, but with differences in the intensity for the generic tablet only. The observed differences could be due to the use of different excipients in the generic product. The possibility of forming a eutectic mixture between the polymeric excipient and metformin in the generic tablet was presumed, which might be attributed to alterations in the physicochemical properties of the drug molecule in the generic product. In conclusion, using different excipients might have a significant effect on the physicochemical properties of drugs in generic formulations, leading to significant changes in drug release behavior.

Manganese-Based Nanozymes: Preparation, Catalytic Mechanisms, and Biomedical Applications

Manganese (Mn) has attracted widespread attention due to its low-cost, nontoxicity, and valence-rich transition. Various Mn-based nanomaterials have sprung up and are employed in diverse fields, particularly Mn-based nanozymes, which combine the physicochemical properties of Mn-based nanomaterials with the catalytic activity of natural enzymes, and are attracting a surge of research, especially in the field of biomedical research. In this review, the typical preparation strategies, catalytic mechanisms, advances and perspectives of Mn-based nanozymes for biomedical applications are systematically summarized. The application of Mn-based nanozymes in tumor therapy and sensing detection, together with an overview of their mechanism of action is highlighted. Finally, the prospective directions of Mn-based nanozymes from five perspectives: innovation, activity enhancement, selectivity, biocompatibility, and application broadening are discussed.

A ratiometric fluorescent sensor for detection of metformin based on terbium-1,10-phenanthroline-nitrogen-doped-graphene quantum dots

Metformin (MTF), an effective biguanide and oral antihyperglycemic agent, is utilized to control blood glucose levels in patients with type II diabetes mellitus, and the determination of its concentration in biological fluids is one of the main issues in pharmacology and medicine. In this work, highly luminescent nitrogen-doped graphene quantum dots (N-GQDs) were modified using terbium (Tb³⁺)–1,10-phenanthroline (Phen) nanoparticles (NPs) to develop a dual-emission ratiometric fluorescent sensor for the determination of MTF in biological samples. The synthesized N-GQDs/Tb–Phen NPs were characterized using different techniques to confirm their physicochemical properties. The N-GQDs/Tb–Phen NPs showed two characteristic emission peaks at 450 nm and 630 nm by exciting at 340 nm that belong to N-GQDs and Tb–Phen NPs, respectively. The results indicated that the emission intensity of both N-GQDs and Tb–Phen NPs enhanced upon interaction with MTF in a concentration-dependent manner. Also, a good linear correlation between the enhanced fluorescence intensity of the system and MTF concentration was observed in the range of 1.0 nM–7.0 μM and the limit of detection (LOD) value obtained was 0.76 nM. In addition, the prepared probe was successfully used for the estimation of MTF concentration in spiked human serum samples. In conclusion, the reported dual-emission ratiometric fluorescent sensor can be used as a sensitive and simple fluorimetric method for the detection of MTF in real samples.

Shcematic representation of the MTF detection by an enhancing mechanism.

Smart active-targeting of lipid-polymer hybrid nanoparticles for therapeutic applications: Recent advances and challenges

The advances in producing multifunctional lipid-polymer hybrid nanoparticles (LPHNs) by combining the biomimetic behavior of liposomes and architectural advantages of polymers have provided great opportunities for selective and efficient therapeutics delivery. The constructed LPHNs exhibit different therapeutic efficacies for special uses based on characteristics of different excipients. However, the high mechanical/structural stability of hybrid nano-systems could be viewed as both a negative property and a positive feature, where the concomitant release of drug molecules in a controllable manner is required. In addition, difficulties in scaling up the LPHNs production, due to involvement of several criteria, limit their application for biomedical fields, especially in monitoring, bioimaging, and drug delivery. To address these challenges bio-modifications have exhibited enormous potential to prepare reproducible LPHNs for site-specific therapeutics delivery, diagnostic and preventative applications. The ever-growing surface bio-functionality has provided continuous vitality to this biotechnology and has also posed desirable biosafety to nanoparticles (NPs). As a proof-of-concept, this manuscript provides a crucial review of coated lipid and polymer NPs displaying excellent surface functionality and architectural advantages. We also provide a description of structural classifications and production methodologies, as well as the biomedical possibilities and translational obstacles in the development of surface modified nanocarrier technology.