Polyelectrolyte mediated nano hybrid particle as a nano-sensor with outstandingly amplified specificity and sensitivity for enzyme free estimation of cholesterol

A hybrid catalyst-triggered cascade reaction for cholesterol detection using a smartphone-based miniature fluorescent apparatus

A new hybrid biological-chemical catalyst, magnetic nanoparticles functionalized with cholesterol oxidase (Fe3O4/APTES/ChOx), was developed for cholesterol detection. In the presence of cholesterol, the enzyme produced H2O2, which facilitated the generation of fluorescent molecules from the fluorogenic substrate with the assistance of Fe3O4 nanoparticles. A smartphone camera with a miniature fluorescent apparatus was used to assess fluorescence emission. Then, a smartphone application was employed to translate the fluorescence intensity to the red, green, and blue (RGB) domain. The developed approach achieved excellent selectivity and acceptable performances while supporting an onsite analysis approach. The practical operational range spanned from 5 to 100 nM, with a detection limit of 0.85 nM. Fe3O4/APTES/ChOx was applied for up to four replicates of reuse and demonstrated stability for at least 30 days. The applicability of the method was evaluated in milk samples, and the results were in accordance with the reference method.

Pharmaceutical Prospects of Curcuminoids for the Remedy of COVID-19: Truth or Myth

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is a positive-strand RNA virus, and has rapidly spread worldwide as a pandemic. The vaccines, repurposed drugs, and specific treatments have led to a surge of novel therapies and guidelines nowadays; however, the epidemic of COVID-19 is not yet fully combated and is still in a vital crisis. In repositioning drugs, natural products are gaining attention because of the large therapeutic window and potent antiviral, immunomodulatory, anti-inflammatory, and antioxidant properties. Of note, the predominant curcumoid extracted from turmeric (Curcuma longa L.) including phenolic curcumin influences multiple signaling pathways and has demonstrated to possess anti-inflammatory, antioxidant, antimicrobial, hypoglycemic, wound healing, chemopreventive, chemosensitizing, and radiosensitizing spectrums. In this review, all pieces of current information related to curcumin-used for the treatment and prevention of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection through in vitro, in vivo, and in silico studies, clinical trials, and new formulation designs are retrieved to re-evaluate the applications based on the pharmaceutical efficacy of clinical therapy and to provide deep insights into knowledge and strategy about the curcumin's role as an immune booster, inflammatory modulator, and therapeutic agent against COVID-19. Moreover, this study will also afford a favorable application or approach with evidence based on the drug discovery and development, pharmacology, functional foods, and nutraceuticals for effectively fighting the COVID-19 pandemic.

Lethal in vitro effects of optimized chitosan nanoparticles against protoscoleces of Echinococcus granulosus

Cystic Echinococcosis (CE) is a parasitic infection caused by the larval stage of Echinococcus granulosus. Exploring safe and effective scolicidal agents for the surgery is an urgent need for the successful treatment of CE. This study aimed to determine scolicidal activity of the synthesized chitosan nanoparticles. Physicochemical properties of synthesized nanoparticles were determined by using DLS, FTIR, and SEM. Different concentrations of chitosan nanoparticles from 125 to 1000 μg/ml were examined at different incubation times (10, 60, 120, and 180 min). Scolicidal and cytotoxic activity of chitosan nanoparticles were confirmed by eosin exclusion and hemolysis activity tests. FTIR spectra, zeta potential (+42 ± 2.08) and PDI (0.388 ± 0.034) value revealed that the chitosan nanoparticles were synthesized. Significant differences among the scolicidal effects of chitosan nanoparticles were observed in comparison to the control treatments and highest scolicidal activity was observed at 1000 μg/ml after 180 min exposure time. Hemolytic activity was not significant at all concentrations of chitosan nanoparticles. Our findings support the hypothesis that Chitosan nanoparticles have the potential to be a safe and efficient scolicidal agent candidate at very low concentrations and in a wide range of exposure time. Further in vivo studies are recommended to evaluate chitosan nanoparticle efficacy before clinical application.

Fluorescence Sensing of Nucleic Acid by Curcumin Encapsulated Poly(Ethylene Oxide)-Block-Poly(Propylene Oxide)-Block-Poly(Ethylene Oxide) Based Nanocapsules

In a novel approach, curcumin has been encapsulated inside Poly(Ethylene Oxide)-Block-Poly(Propylene Oxide)-Block-Poly(Ethylene Oxide) (F108) nanocapsules. FTIR spectra have indicated a type of hydrogen bonding and dipole interaction between curcumin and F108. Fluorescence and UV-visible absorption profiles of curcumin in nanocapsules have indicated location of curcumin in more hydrophobic microenvironment. The relative fluorescence yield has increased by 6 times in the nanocapsules, which renders them as more sensitive probes to be used later on in sensing study. Therefore, based on the functionality of curcumin as a fluorescent transducer, encapsulated curcumin is used in biomedical application as DNA and RNA sensing. Detection limits are detected as 50 μM and 60 μM for DNA and RNA respectively. Linear dynamic concentration range obtained in this proposed method is much higher than reported in literature. The interaction between the nanocapsules and targeted DNA/RNA molecules is further approved by zeta potential studies. Furthermore, the real interaction of DNA with the encapsulated curcumin is confirmed by the interaction of the adenine and cytosine nucleotides. This has been verified through zeta potential measurements. Moreover, our prepared nanocapsules has presented a high percentage recovery of DNA and RNA (96-101%). Finally, stability results have illustrated a high photostability of encapsulated curcumin, indicating that proposed nanocapsules can be considered as a stable sensor during measurement time.

Microfluidically prepared sensor particles for determination of chloride by fluorescence quenching of matrix-embedded lucigenin

Abstract

Polyacrylamide sensor particles have been synthesized by using a microfluidic arrangement for generation of microdroplets containing a reaction mixture for forming gel microparticles. The droplets are formed in an inert carrier liquid immiscible with the reaction mixture based on aqueous solutions. Gel particles are formed in situ by photochemical initiation of polymerization inside droplets using an UV-sensitive photoinitiator. In result, water-swellable spheres with submillimetre size are obtained. Those spheres were loaded with N,N′-dimethyl-9,9′-biacridinium dinitrate (lucigenin) as ion selective fluorescence probe for chloride. The particles can be dried, stored and re-swollen. Upon exposure of dried particles to sodium chloride solutions they showed dynamic fluorescence quenching obeying the linear plot of Stern–Volmer-equation between 0 and 130 mM Cl−. Thus, chloride concentrations up to 50 mM could be measured with appropriate accuracy. The particles allow a fast optical determination of chloride in tiny analyte volumes down to below ten microliters.

Graphic abstract

Aggregation-induced emission of copper nanoclusters triggered by synergistic effect of dual metal ions and the application in the detection of H2O2 and related biomolecules

Recently, the aggregation-induced emission (AIE) of nanoclusters triggered by metal ions has been received great attentions. However, the good AIE efficiency usually requires excessive metal ions, which may result in an undesired competition between metal ions and targets. In this work, by the synergistic effect of Pb²⁺ and Zr⁴⁺, a fewer amounts of metal ions can induce more aggregates of glutathione-capped Cu nanoclusters (CSH-CuNCs), resulting in a higher AIE efficiency. Next, by virtue of the oxidative property of H₂O₂, the AIE of GSH-CuNCs-Pb²⁺-Zr⁴⁺ system quenches linearly with the concentration of H₂O₂ from 1 to 60 μmol/L. Moreover, many biological substrates, such as glucose and cholesterol, can generate H₂O₂ in the presence of their specific oxidases and O₂. Therefore, the detection of glucose or cholesterol can also be achieved by the proposed method, and the limits of detection of glucose and cholesterol are 0.37 and 2.7 μmol/L, respectively. Finally, this method has been validated to be sensitive and selective for glucose or cholesterol detection in human serum samples.

Nanomaterial-based biosensors for measurement of lipids and lipoproteins towards point-of-care of cardiovascular disease

Cardiovascular disease (CVD) has become the primary cause of global deaths and inflicts an enormous healthcare burden on both developed and developing countries. Frequent monitoring of CVD-associated risk factors such as the level of lipids (e.g., triglyceride (TG) and total cholesterol (TC)) and lipoproteins (e.g., low-density lipoprotein (LDL) and high-density lipoprotein (HDL)) can effectively help prevent disease progression and improve clinical outcomes. However, measurement of these risk factors is generally integrated into an automated analyzer, which is prohibitively expensive and highly instrument-dependent for routine testing in primary care settings. As such, a variety of rapid, simple and portable nanomaterial-based biosensors have been developed for measuring the level of lipids (TG and TC) and lipoproteins (LDL and HDL) towards the management of CVD at the point-of-care (POC). In this review, we first summarize traditional methods for measurement of lipids and lipoproteins, and then present the latest advances in developing nanomaterial-based biosensors that can potentially monitor the risk factors of CVD at the POC.

Synthesis, spectral characterization, molecular modeling, antibacterial and antioxidant activities and stability study of binuclear Pd(II) and Ru(III) complexes with novel bis-[1-(2-[(2-hydroxynaphthalen-1-yl)methylidene]amino}ethyl)-1-ethyl-3-phenylthiourea] ligand: Application to detection of cholesterol

A novel bis-[1-(2-[(2-hydroxynaphthalen-1-yl) methylidene]amino}ethyl)-1-ethyl-3-phenylthiourea] Schiff base (L) and its binuclear palladium and ruthenium complexes have been prepared and characterized by ESI-MS, elemental analysis, NMR (¹H NMR, ¹³C NMR, COSY, NEOSY and HSQC), FT-IR, ATR, UV-Visible spectra, TGA measurements, conductivity and cyclic voltammetry. The experimental results and the molecular parameters calculated using DFT method revealed a square planar geometry around Pd and octahedral geometry around ruthenium metal. The antibacterial activity of the ligand L and its complexes was evaluated against different human bacteria. In addition, the formation constants of the synthesized Schiff base-metal complexes and the systems formed with these chelates and cholesterol were estimated using spectrophotometric technique. The detection of cholesterol using novel Pd and Ru Schiff base complexes was studied using fluorometric method, and the measurements showed that the sensitive fluorometric response towards cholesterol analysis was determined using palladium complex. The limit of detection (LOD) of cholesterol calculated using this complex (4.6 μM) is lower (better) than LOD found using ruthenium complex (19.1 μM) and different compounds previously published around linear range of 0-5 mM.

Sensors Based on Bio and Biomimetic Receptors in Medical Diagnostic, Environment, and Food Analysis

Analytical chemistry is now developing mainly in two areas: automation and the creation of complexes that allow, on the one hand, for simultaneously analyzing a large number of samples without the participation of an operator, and on the other, the development of portable miniature devices for personalized medicine and the monitoring of a human habitat. The sensor devices, the great majority of which are biosensors and chemical sensors, perform the role of the latter. That last line is considered in the proposed review. Attention is paid to transducers, receptors, techniques of immobilization of the receptor layer on the transducer surface, processes of signal generation and detection, and methods for increasing sensitivity and accuracy. The features of sensors based on synthetic receptors and additional components (aptamers, molecular imprinted polymers, biomimetics) are discussed. Examples of bio- and chemical sensors' application are given. Miniaturization paths, new power supply means, and wearable and printed sensors are described. Progress in this area opens a revolutionary era in the development of methods of on-site and in-situ monitoring, that is, paving the way from the "test-tube to the smartphone".