Surface plasmon resonance of gold nanoparticles as a colorimetric sensor for indirect detection of Cefixime

Synthesis and Properties of Cefixime Core-Shell Magnetic Nano-Molecularly Imprinted Materials

Novel core-shell magnetic molecularly imprinted polymers (MMIPs) were synthesized using the sol-gel method for the adsorption of cefixime (CFX). Fe3O4@SiO2 is the core, and molecularly imprinted polymers (MIPs) are the shell, which can selectively interact with CFX. The preparation conditions, adsorption kinetics, adsorption isotherms, selective adsorption ability, and reutilization performance of the MMIPs were investigated. The adsorption capacity of MMIPs for CFX was 111.38 mg/g, which was about 3.5 times that of MNIPs. The adsorption equilibrium time was 180 min. The dynamic adsorption experiments showed that the adsorption process of MMIPs to CFX conformed to the pseudo-second-order model. Through static adsorption study, the Scatchard analysis showed that MMIPs had two types of binding sites-the high-affinity binding sites and the low-affinity binding sites-while the Langmuir model fit the adsorption isotherms well (R2 = 0.9962). Cefepime and ceftiofur were selected as the structural analogs of CFX for selective adsorption studies; the adsorption of CFX by MMIPs was higher than that of other structural analogs; and the imprinting factors of CFX, cefepime, and ceftiofur were 3.5, 1.7, and 1.4, respectively. Furthermore, the MMIPs also showed excellent reusable performance.

Surfactant stabilized gold nanomaterials for environmental sensing applications - A review

Surfactant stabilized Gold (Au) nanomaterials (NMs) have been documented extensively in recent years for numerous sensing applications in the academic literature. Despite the crucial role these surfactants play in the sensing applications, the comprehensive reviews that highlights the fundamentals associated with these assemblies and impact of these surfactants on the properties and sensing mechanisms are still quite scare. This review is an attempt in organizing the vast literature associated with this domain by providing critical insights into the fundamentals, preparation methodologies and sensing mechanisms of these surfactant stabilized Au NMs. For the simplification, the surfactants are divided into the typical and advanced surfactants and the Au NMs are classified into Au nanoparticles (NPs) and Au nanoclusters (NCs) depending upon the complexity in structure and size of the NMs respectively. The preparative methodologies are also elaborated for enhancing the understanding of the readers regarding such assemblies. The case studies regarding surfactant stabilized Au NMs were further divided into colorimetric sensors, surface plasmonic resonance (SPR) based sensors, luminescence-based sensors, and electrochemical/electrical sensors depending upon the property utilized by the sensor for the sensing of an analyte. Future perspectives are also discussed in detail for the researchers looking for further progress in that particular research domain.

Using Gold Nanoparticles for Ultra-trace Spectrophotometric Determination of Sitagliptin Drug in Various Real Samples

Background:

The determination of trace drugs in aquatic environments is important. For this purpose, many methods such as High Performance Liquid Chromatography (HPLC) and gas chromatography mass spectrometry (GC/MS) have been used.

Objective:

This study introduces a simple, sensitive, and rapid colorimetric method for the spectrophotometric determination of sitagliptin (STG) in drinking water, tablet, human plasma, and human urine using gold nanoparticles (AuNPs).

Methods:

The Surface Plasmon Resonance (SPR) property of AuNPs and the interaction between STG and AuNPs are the base of the colorimetric method. The addition of STG into AuNPs led to the aggregation of AuNPs. Transmission Electron Microscopy (TEM) proved the aggregation of AuNPs in the presence of STG. Also, the size of the nanoparticles distribution was evaluated by Dynamic Light Scattering (DLS). In addition, Fourier-Transform Infrared Spectrophotometer (FTIR) was used to study the chemical structure of AuNPs, STG, and AuNPs in the presence of STG.

Results:

The parameters that affect the absorbance such as pH, type and volume of buffer, AuNPs concentration, interaction time, ionic strength, and interfering ions were investigated and optimized. Under the optimum conditions, the determination of STG was performed via this method over the range of 50-300 μgL-1 (R2=0.9941) with the Limit of Detection (LOD) and Limit of Quantification (LOQ) of 1.23 and 1.39 μgL-1, respectively.

Conclusion:

Eventually, the results showed that the proposed method has a high potential for simple, rapid, sensitive, and accurate determination of STG.

An ultra-sensitive optical aptasensor based on gold nanoparticles/poly vinyl alcohol hydrogel as acceptor/emitter pair for fluorometric detection of digoxin with on/off/on strategy

A novel nanobiosensor was prepared by aptamer and gold nanoparticles conjugate in poly vinyl alcohol hydrogel for sensitive detection of digoxin in human plasma samples. The developed nanobiosensor was characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and dynamic light scattering instrument. In this sensor the hydrogel acted as a fluorescent probe. The fluorescence intensity of the hydrogel was quenched by aptamer stabilized gold nanoparticles as energy acceptor. Upon addition of digoxin, the aptamer/drug complex was formed and the fluorescence of the hydrogel was restored because of destabilization and aggregation of gold nanoparticles in the presence of salt. The affecting parameters on the nanobiosensor performance were assessed and under the optimized conditions the external and in plasma calibration curves were linear in the 10-1000 ng L^-1 digoxin concentration range with detection limits of 2.9 and 3.1 ng L^-1, respectively. The relative standard deviations for 5 replicate determinations of 50, 250, and 500 ng L^-1 of digoxin, were 7.3, 5.1, and 3.8%, respectively. This nanofluoroprobe was successfully applied for determination of digoxin in spiked plasma samples without any pretreatment procedure.

Recent development of antibiotic detection in food and environment: the combination of sensors and nanomaterials

In recent years, the abuse of antibiotics has led to the pollution of soil and water environment, not only poultry husbandry and food manufacturing will be influenced to different degree, but also the human body will produce antibody. The detection of antibiotic content in production and life is imperative. In this review, we provide comprehensive information about chemical sensors and biosensors for antibiotic detection. We classify the currently reported antibiotic detection technologies into chromatography, mass spectrometry, capillary electrophoresis, optical detection, and electrochemistry, introduce some representative examples for each technology, and conclude the advantages and limitations. In particular, the optical and electrochemical methods based on nanomaterials are discussed and evaluated in detail. In addition, the latest research in the detection of antibiotics by photosensitive materials is discussed. Finally, we summarize the pros and cons of various antibiotic detection methods and present a discussion and outlook on the expansion of cross-scientific areas. The synthesis and application of optoelectronic nanomaterials and aptamer screening are discussed and prospected, and the future trends and potential impact of biosensors in antibiotic detection are outlined.Graphical abstract.

Quantitative analysis of solid dosage forms of cefixime using Raman spectroscopy

Quantification of antibiotics is of significant importance because of their use in the prevention and treatment of different diseases. Cefixime (CEF) is a cephalosporin antibiotic that is used against bacterial infections. In the present study, Raman spectroscopy has been applied for the identification and quantification of Raman spectral features of cefixime with different concentrations of Active Pharmaceutical Ingredient (API) and excipients in solid dosage forms. The changes in Raman spectral features of API and excipients in the solid dosage forms of cefixime were studied and Raman peaks were assigned based on the literature. Multivariate data analysis techniques including the Principal Component Analysis (PCA) and Partial Least Squares Regression analysis (PLSR) have been performed for the qualitative and quantitative analysis of solid dosage forms of cefixime. PCA was found helpful in differentiating all the Raman spectral data associated with the different solid dosage forms of cefixime. The coefficient of determination (R²), mean absolute error (MAE), and mean relative error (MRE) for the calibration data-set were 0.99, 0.72, and 0.01 respectively and for the validation data-set were 0.99, 3.15, and 0.02 respectively, that shows the performance of the model. The root mean square error of calibration (RMSEC) and root mean square error of prediction (RMSEP) were found to be 0.56 mg and 3.13 mg respectively.

Simultaneous ultra-trace quantitative colorimetric determination of antidiabetic drugs based on gold nanoparticles aggregation using multivariate calibration and neural network methods

In this study, a simple and rapid method was investigated for the simultaneous ultra-trace colorimetric determination of Metformin (MET) and Sitagliptin (STG) based on the aggregation of gold nanoparticles (AuNPs). The Morphology and size distribution of synthesized AuNPs before and after adding drug (Zipmet) were monitored using transmission electron microscopy (TEM) and dynamic light scattering (DLS), respectively. By adding a drug, the absorption peak was shifted from 520 to 650 nm. The colorimetric method along with partial least squares (PLS) as a multivariate calibration method, as well as neural network time series were applied to estimate MET and STG simultaneously. The percentage of the mean recovery and root mean square error (RMSE) of the test set of mixtures related to the MET and STG were obtained 99.96, 1.1301 and 99.77, 1.0106, respectively. On the other hand, the regression coefficient (R²) of the training, validation, and test sets corresponding to the artificial neural network (ANN) were close to one for both components. Eventually, the proposed method was compared with a reference technique named high-performance liquid chromatography (HPLC) by analysis of variance (ANOVA) test and there was no significant difference between them.

A novel strategy for detection of small molecules based on aptamer/gold nanoparticles/graphitic carbon nitride nanosheets as fluorescent biosensor

Herein, a novel ultrasensitive strategy has been developed by designing a label free fluorescent nano-aptasensor for monitoring of small moecules in human plasma. In this nano-aptasensor, graphitic carbon nitride nanosheets were used as fluorescent probe. The fluorescence intensity of the probe was decreased by interaction between graphitic carbon nitride nanosheets and label-free aptamer/gold nanoparticles conjugate, via Fluorescence resonance energy transfer mechanism. Upon addition of the analyte, the fluorescence of graphitic carbon nitride nanosheets was restored due to the aptamer/analyte interaction, and the aggregation of gold nanoparticles in the presence of salt. The influence of various factors on sensing method was investigated, and under the approved conditions, the fluorescence signal showed a linear relation with Digoxin concentration in the range of 10-500 ng L^-1 with limit of detection down to 3.2 ng L^-1 relative standard deviations for 25, 100 and 500 ng L^-1 of analyte concentrations were 2.6, 4.0 and 6.5%, respectively. This strategy provided a simple, rapid, cost effective and reproducible experimental model, with successful application for determination of Digoxin in plasma samples without any pretreatment steps.