Label-free silver nanoparticles for the naked eye detection of entecavir

Silver Nanoparticles Application as a Colorimetric Probe for the Spectrophotometric Determination of Hyoscine Butylbromide in Pharmaceutical Formulations

BACKGROUND

Hyoscine butylbromide is used as an antispasmodic in treating peptic ulcers, gastritis, and various disorders of the gastrointestinal tract that are characterized by spasms. It has also found employment for the relief of spasmodic conditions of the bile duct and urinary tract and for the treatment of dysmenorrhea.

OBJECTIVE

In this study, the application of silver nanoparticles (Ag NPs) as a colorimetric probe for the fast, selective, and simple determination of hyoscine butylbromide was described.

METHODS

The proposed method was based on the Ag NPs aggregation induced by their interaction with the cited drug. This interaction produced a color change from yellow to colorless measured at 405 nm.

RESULTS

The method linear concentration range was 0.10-50.0 µg/mL with a correlation equation (y = 0.0132 x + 0.3174), correlation coefficient of 0.9981, and quantification limits of 0.091 µg/mL. A thorough investigation was done to validate the method's analytical performance, and the findings were satisfactory. With great accuracy and precision, this approach was used to identify the medication in pharmaceutical tablet samples with recovery percentages ranging from 96.20 to 98.10%.

CONCLUSIONS

Since there are no critical reaction conditions or solvent extraction involved in the described method, it is distinguished by its simplicity. The results were quite consistent with those attained using the approved standard method.

HIGHLIGHTS

Simple, fast, and sensitive colorimetric probe developed for determination of hyoscine butylbromide in pharmaceutical formulations.

Green chemistry approach: method development and validation for identification and quantification of entecavir using FT-IR in bulk and pharmaceutical dosage form

Background

Chemical hazard is one of the most prominent side effects that come out along with the benefits of pharmaceutical production. Chemicals usage and waste production are involved in each step of production and are found to be in high percentage at the stage of quality testing. Conventional quality testing (assay) involves the use of solvents and reagents that generates high flammable and non-flammable waste and also enhanced the per batch cost of the medicine, whereas green chemistry offers a benign environment for drug designing, manufacturing, and analysis.

Results

In the present study, a green FTIR method for assay of antiviral drugs entecavir is developed and validated as per ICH Q2_R1 guidelines. A calibration curve is plotted between absorbance and concentration, yielding excellent linearity with a correlation coefficient (r2) value of 0.9991 in the concentration range of 0.25–0.75 mg.

Conclusion

The developed method was validated and was very specific, accurate (99.9–100%) at three levels of 80, 100, and 120% of test concentration and precise with < 1% RSD. The LOD of the method is 0.0674 mg and is able to quantify the active at the limit of 0.2042 mg. Four different drug brands available in the local market are assayed by the validated method, and %recoveries are found to be in the range of 99–101%.

Graphical abstract

Green Chemistry Approach: Method Development and Validation for Identification and Quantification of Entecavir using FT-IR in Bulk and Pharmaceutical Dosage Form

Nanoparticle-based Point of Care Immunoassays for in vitro Biomedical Diagnostics

In resource-limited settings, the availability of medical practitioners and early diagnostic facilities are inadequate relative to the population size and disease burden. To address cost and delayed time issues in diagnostics, strip-based immunoassays, e.g. dipstick, lateral flow assay (LFA) and microfluidic paper-based analytical devices (microPADs), have emerged as promising alternatives to conventional diagnostic approaches. These assays rely on chromogenic agents to detect disease biomarkers. However, limited specificity and sensitivity have motivated scientists to improve the efficiency of these assays by conjugating chromogenic agents with nanoparticles for enhanced qualitative and quantitative output. Various nanomaterials, which include metallic, magnetic and luminescent nanoparticles, are being used in the fabrication of biosensors to detect and quantify biomolecules and disease biomarkers. This review discusses some of the principles and applications of such nanoparticle-based point of care biosensors in biomedical diagnosis.

Surface plasmon resonance based selective and sensitive colorimetric determination of azithromycin using unmodified silver nanoparticles in pharmaceuticals and human plasma

In this article we report a novel method for colorimetric sensing and selective determination of a non-chromophoric drug-azithromycin, which lacks native absorbance in the UV-Visible region using unmodified silver nanoparticles (AgNPs). The citrate-capped AgNps dispersed in water afforded a bright yellow colour owing to the electrostatic repulsion between the particles due to the presence of negatively charged surface and showed surface plasmon resonance (SPR) band at 394nm. Addition of positively charged azithromycin at a concentration as low as 0.2μM induced rapid aggregation of AgNPs by neutralizing the negative charge on the particle surface. This phenomenon resulted in the colour change from bright yellow to purple which could be easily observed by the naked eye. This provided a simple platform for rapid determination of azithromycin based on colorimetric measurements. The factors affecting the colorimetric response like pH, volume of AgNPs suspension and incubation time were suitably optimized. The validated method was found to work efficiently in the established concentration range of 0.2-100.0μM using two different calibration models. The selectivity of the method was also evaluated by analysis of nanoparticles-aggregation response upon addition of several anions, cations and some commonly prescribed antibiotics. The method was successfully applied for the analysis of azithromycin in pharmaceuticals and spiked human plasma samples with good accuracy and precision. The simplicity, efficiency and cost-effectiveness of the method hold tremendous potential for the analysis of such non-chromophoric pharmaceuticals.

Colorimetric recognition of pazufloxacin mesilate based on the aggregation of gold nanoparticles

A novel colorimetric nanomaterial-assisted optical sensor for pazufloxacin mesilate was proposed for the first time. Pazufloxacin mesilate could induce the aggregation of glucose-reduced gold nanoparticles (AuNPs) through hydrogen-bonding interaction and electrostatic attraction, leading to the changes in color and absorption spectra of AuNPs. The effect of different factors such as pH, the amount of AuNPs, reaction time and reaction temperature was inspected. Under the optimum condition, UV-vis spectra showed that the absorption ratio (A670/A532) was linear with the concentration of pazufloxacin mesilate in the range from 9×10(-8) mol L(-1) to 7×10(-7) mol L(-1) with a linear coefficient of 0.9951. This method can be applied to detecting pazufloxacin mesilate with an ultralow detection limit of 7.92×10(-9) mol L(-1) without any complicated instruments. Through inspecting other analytes and ions, the anti-interference performance of AuNP detection system for pazufloxacin mesilate was excellent. For its high efficiency, rapid response rate as well as wide linear range, it had been successfully used to the analysis of pazufloxacin mesilate in human urine quantificationally.

Biomedical Probes Based on Inorganic Nanoparticles for Electrochemical and Optical Spectroscopy Applications

Inorganic nanoparticles usually provide novel and unique physical properties as their size approaches nanometer scale dimensions. The unique physical and optical properties of nanoparticles may lead to applications in a variety of areas, including biomedical detection. Therefore, current research is now increasingly focused on the use of the high surface-to-volume ratios of nanoparticles to fabricate superb chemical- or biosensors for various detection applications. This article highlights various kinds of inorganic nanoparticles, including metal nanoparticles, magnetic nanoparticles, nanocomposites, and semiconductor nanoparticles that can be perceived as useful materials for biomedical probes and points to the outstanding results arising from their use in such probes. The progress in the use of inorganic nanoparticle-based electrochemical, colorimetric and spectrophotometric detection in recent applications, especially bioanalysis, and the main functions of inorganic nanoparticles in detection are reviewed. The article begins with a conceptual discussion of nanoparticles according to types, followed by numerous applications to analytes including biomolecules, disease markers, and pharmaceutical substances. Most of the references cited herein, dating from 2010 to 2015, generally mention one or more of the following characteristics: a low detection limit, good signal amplification and simultaneous detection capabilities.

An injectable liquid crystal system for sustained delivery of entecavir

Liquid crystal (LC) technology has attracted much interest for new injectable sustained-release (SR) formulations. In this study, an injectable liquid crystal-forming system (LCFS) including entecavir was prepared for the treatment of hepatitis B. In particular, an anchoring effect was introduced because LCFSs are relatively hydrophobic while entecavir is a slightly charged drug. The physicochemical properties of LCFSs were investigated by cryo-transmission electron microscopy (cryo-TEM), polarized optical microscopy, and small-angle X-ray scattering (SAXS), showing typical characteristics of the liquid crystalline phase, which was classified as the hexagonal phase. A pharmacokinetic study in rats showed sustained release of entecavir for 3-5 days with a basic LCFS formulation composed of sorbitan monooleate (SMO), phosphatidyl choline (PC), and tocopherol acetate (TA) as the main LC components. 1,2-Dipalmitoyl-sn-glycero-3-phosphatidic acid (DPPA), an anionic phospholipid, was added to increase the anchoring effect between the cationic entecavir and the anionic DPPA, which resulted in a 1.5-times increase in half-life in rats. In addition, anchoring was strengthened by optimizing the pH to 2.5-4.5, increasing the half-life in the rat and dog. Also, due to the increasing terminal half-life from rat to dog resulting from species differences, LCFS produced one week delivery of entecavir in rat and two weeks delivery in dog. Therefore, LCFS injection using the anchoring effect for entecavir can potentially be used to deliver the drug over more than 2 weeks or even 1 month for the treatment of hepatitis B.

Colorimetric determination of o-phenylenediamine in water samples based on the formation of silver nanoparticles as a colorimetric probe

A simple, rapid and cost-effective method for visual colorimetric detection of o-phenylenediamine (OPD) based on the formation of silver nanoparticles (AgNPs) has been developed in this paper. Silver ions can be reduced to AgNPs by OPD in a few minutes, causing changes in absorption spectra and color of the reaction system. Therefore, colorimetric detection of OPD could be realized by a UV-vis spectrophotometer or even the naked eye. Results showed that the absorption intensity of AgNPs at 416 nm exhibited a good linear correlation (R2=0.998) with OPD concentration in the range from 10(-6) to 8×10(-5) mol L(-1) and the detection limit (3σ/S) was calculated to be 1.61×10(-7) mol L(-1). Furthermore, as low as 4×10(-6) mol L(-1)OPD can be visualized by the naked eye without the requirement of any complicated or expensive instruments. This proposed method has been successfully applied to determine OPD in water samples, and may provide an innovative platform in the development of sensors for guiding environmental monitoring in the future.