Sharif Digital Repository

Array-based sensor is an interesting approach that suggests an alternative to expensive analytical methods. In this work, we introduce a novel, simple, and sensitive nanoparticle-based chemiluminescence (CL) sensor array for discrimination of biothiols (e.g., cysteine, glutathione and glutathione disulfide). The proposed CL sensor array is based on the CL efficiencies of four types of enhanced nanoparticle-based CL systems. The intensity of CL was altered to varying degrees upon interaction with biothiols, producing unique CL response patterns. These distinct CL response patterns were collected as "fingerprints" and were then identified through chemometric methods, including linear... 

There is a growing interest in developing high-performance sensors monitoring organophosphate pesticides, primarily due to their broad usage and harmful effects on mammals. In the present study, a colorimetric sensor array consisting of citrate-capped 13 nm gold nanoparticles (AuNPs) has been proposed for the detection and discrimination of several organophosphate pesticides (OPs). The aggregation-induced spectral changes of AuNPs upon OP addition has been analyzed with pattern recognition techniques, including hierarchical cluster analysis (HCA) and linear discriminant analysis (LDA). In addition, the proposed sensor array has the capability to identify individual OPs or mixtures of them in... 

A simple and effective ratiometric fluorescence sensor for selective detection of dopamine (DA) in alkaline media has been developed by simply mixing thioglycolic acid (TGA) functionalized orange fluorescent cadmium telluride (CdTe) quantum dots (QDs) with amino-functionalized blue fluorescent carbon nanodots (CDs). Under a single excitation wavelength of 365 nm, the sensor exhibits dual-emissions centered at 445 and 603 nm. The fluorescence of CdTe QDs is selectively quenched by DA, whereas the fluorescence of CDs is insensitive to the analyte. In the presence of different amounts of DA, the variations in the dual emission intensity ratios exhibit a continuous color change from pink to... 

Most array-based sensing platforms, to date, utilize static response patterns for discrimination of a wide variety of analytes, but only a few studies have focused on the important task of quantitatively resolving structural isomers, which are nowadays important because of their broad usage in medicines and industries. A possible way of accomplishing this feat is to combine kinetic (rather than static) sensor response profiles with the chemical tongue strategy to allow the development of array-based sensors for isomeric discrimination. Here, by adding the time dimension, a simple and novel gold nanorod (AuNR)-based chrono-colorimetric sensor array is proposed for chemical discrimination... 

Detection of nitroaromatic explosives is of strong concern because of human health, public safety, environment, and military issues. In this study, we present a ratiometric sensor array for detection and discrimination of widely-used nitroaromatics (i.e., 2,4,6-trinitrotoluene (TNT), 2,4,6-trinitrophenol (TNP), and 2,4-dinitrotoluene (DNT)). In the design of sensor elements (SE) we employ blue emissive carbon dots (BCDs) in combination with yellow (SE-A) and red (SE-B) emissive cadmium telluride quantum dots (CdTe QDs). The fluorescence intensity of BCDs, YQDs, and RQDs is quenched by TNT, DNT, and TNP in various degrees. Both TNT and TNP cause the quenching and spectral shift of BCDs (TNT... 

Development of a convenient and inexpensive method for identification and detection of nanoparticles (NPs) is of great interest. In this work, we have developed a novel and simple chemiluminescence based sensor array, with its sensing mechanism mimicking that of olfactory and gustatory systems for discriminating a set of NPs. The proposed method is based on the enhancement effect of NPs on luminol–oxidant CL intensity by their catalytic effect. Three kinds of oxidant including H2O2, AgNO3, and K3Fe(CN)6 were used as sensor elements and NPs exhibited diverse enhancing responses to different oxidant-luminol CL systems producing unique response patterns that were identified through heat map and... 

The widespread use of pesticides in pest management has boosted the demands for developing highly sensitive probes for on-site monitoring. Herein we presented a sensitive enzyme-free ratiometric probe for determination of methyl parathion (MP), as an organophosphate pesticide using TGA-capped CdTe QDs and carbon dots (CDs). Unlike previous methods in which hydrolysis product of MP is instrumental in the response of the sensors, here, self-assembly of cetyltrimethylammonium bromide (CTAB) on the surface of non-modified yellow-emissive CdTe QDs facilitates the quenching of CTAB-QDs upon addition of MP while the fluorescence intensity of CDs remains constant. Using a smartphone, the ratiometric... 

The study on the mechanism of the shape evolution of nanocrystaline particles is an important and emerging field, which is applicable in the shaped control synthesis of nanoparticles. As an alternative to transmittance electron microscopy (TEM), which is already used in the study of nanoparticles, in this article a simple spectrophotometric method has been proposed utilizing the advantages of chemometrics methods in analyzing overlapped and complex spectral data. The evolutionary visible absorbance data of CdSe quantum dots through particle formation were analyzed by factor analysis, evolving factor analysis, and multivariate curve resolution-alternative least-squares analysis, by which four... 

A novel, simple and rapid spectrophotometric method for the determination of nitrophenol (NP) isomer mixtures based on the catalytic activity of gold nanoparticles is described. Gold nanoparticle (∼13 nm) solution was used to catalyze the reduction of NP isomers to aminophenols with an excess amount of NaBH4. The second-order data were obtained by spectrophotometrically monitoring the reduction process of NP isomers. So, multivariate curve resolution optimized by alternative least squares (MCR-ALS) was used to analyze such data. MCR-ALS, an appropriate second-order method, can exploit the so-called 'second order advantage' (the ability to determine in the presence of uncalibrated... 

An indirect colorimetric method is presented for spectrophotometric determination of hydrazine, phenylhydrazine, and isoniazid. Reduction of silver ions to silver nanoparticles (AgNPs) by these analytes as active reducing agents in the presence of polyvinylpyrrolidone (PVP) and also cetyltrimethylammonium chloride (CTAC) as a stabilizer is the basis of the proposed method. The changes in plasmon absorbance of the AgNPs at λ = 415 nm in the presence of PVP were proportional to concentration of hydrazine, phenylhydrazine, and isoniazid in the ranges of 4.0-150.0 μM, 1.0-55.0 μM, and 2.0-30.0 μM, respectively, and the detection limit obtained was 0.79 μM. In the presence of CTAC, the linear... 

A multicomponent analysis method based on principal component analysis-artificial neural network model (PC-ANN) is proposed for the simultaneous determination of levodopa (LD) and benserazide hydrochloride (BH). The method is based on the reaction of levodopa and benserazide hydrochloride with silver nitrate as an oxidizing agent in the presence of PVP and formation of silver nanoparticles. The reaction monitored at analytical wavelength 440 nm related to surface plasmon resonance band of silver nanoparticles. Differences in the kinetic behavior of the levodopa and benserazide hydrochloride were exploited by using principal component analysis, an artificial neural network (PC-ANN) to resolve... 

A nano-based sensor array has been developed for identification and discrimination of catecholamine neurotransmitters based on optical properties of their oxidation products under alkaline conditions. To produce distinct fluorescence response patterns for individual catecholamine, quenching of thioglycolic acid functionalized cadmium telluride (CdTe) quantum dots, by oxidation products, were employed along with the variation of fluorescence spectra of oxidation products. The spectral changes were analyzed with hierarchical cluster analysis (HCA) and principal component analysis (PCA) to identify catecholamine patterns. The proposed sensor could efficiently discriminate the individual... 

In this paper, we present a simple platform for colorimetric detection of glutathione using gold nanorods (AR ∼ 6.5 ± 0.2) as a plasmonic sensor. The functional mechanism of the sensor is based on shifts of longitudinal plasmon resonance during selective transverse overgrowth induced by preferential binding of glutathione at the nanorod tips. Under the optimum conditions, a calibration curve showed two linear regimes at the range of 50 nM to 20 μM of glutathione with a detection limit as low as 40 nM. The nanosensor maintains relatively high selectivity for determination of glutathione in the presence of several other amino acids. However, cysteine at similar concentration levels strongly... 

There are, to date, few general answers to fundamental questions related to the interactions of nanoparticles (NPs) with living cells. Studies reported in the literature have delivered only limited principles about the nano-bio interface and thus the biological behavior of NPs is yet far from being completely understood. Combining computational tools with experimental approaches in this regard helps to precisely probe the nano-bio interface and allows the development of predictive and descriptive relationships between the structure and the activity of nanomaterials. In the present contribution, a nano-quantitative structure-activity relationship (nano-QSAR) model has been statistically... 

Developments of sensitive, rapid, and cheap systems for identification of a wide range of biomolecules have been recognized as a critical need in the biology field. Here, we introduce a simple colorimetric sensor array for detection of biological thiols, based on aggregation of three types of surface engineered gold nanoparticles (AuNPs). The low-molecular-weight biological thiols show high affinity to the surface of AuNPs; this causes replacement of AuNPs' shells with thiol containing target molecules leading to the aggregation of the AuNPs through intermolecular electrostatic interaction or hydrogen-bonding. As a result of the predetermined aggregation, color and UV-vis spectra of AuNPs... 

In this study, a multivariate-based strategy was developed for simultaneous determination of thirteen carcinogenic polycyclic aromatic hydrocarbons (PAHs) in water samples using gold nanoparticles (AuNPs) as solid-phase extraction (SPE) sorbent combined with gas chromatography (GC). The extraction technique is based on the strong affinity between citrate-capped AuNPs and PAHs. Furthermore, characterization of AuNPs was performed by UV-vis spectroscopy and transmission electron microscopy (TEM) techniques. A rotatable central composite design (CCD) combined with multiple linear regression (MLR) was used for designing the extraction procedure and developing models using the GC peak areas of 13... 

A nano-based sensor array has been developed for identification and discrimination of catecholamine neurotransmitters based on optical properties of their oxidation products under alkaline conditions. To produce distinct fluorescence response patterns for individual catecholamine, quenching of thioglycolic acid functionalized cadmium telluride (CdTe) quantum dots, by oxidation products, were employed along with the variation of fluorescence spectra of oxidation products. The spectral changes were analyzed with hierarchical cluster analysis (HCA) and principal component analysis (PCA) to identify catecholamine patterns. The proposed sensor could efficiently discriminate the individual... 

Herein, we demonstrate a simple yet novel luminescence assay for visual chiral discrimination of cysteine. Thioglycolic acid (TGA)-capped cadmium-telluride (CdTe) quantum dots (QDs) exposing green emission were directly synthesized in aqueous solution. The interaction between cysteine molecules and CdTe QDs induced the aggregation of QDs via hydrogen bonding. As a result of electronic coupling within these aggregates, a redshift both in the absorption and emission spectra of QDs occured. The difference in the kinetics of the interactions between L- A nd D-cysteine with CdTe QDs led to chiral recognition of these enantiomers. Addition of D-cysteine to CdTe QDs in a basic media caused a... 

This paper describes a simple and low-cost test strip for on-site monitoring of methiocarb insecticide. Hydrophilic filter paper soaked in agarose solution was bounded by hydrophobic solid wax and then was coated with unmodified gold nanoparticles (AuNPs). AuNPs aggregation caused by methiocarb served as colorimetric response. We demonstrated detection capability of methiocarb both in solution- and substrate-based sensor. A good linear relationship was obtained between the colorimetric response and the concentration of methiocarb ranging from 20 to 80 ng mL -1 with a limit of detection of 5 ng mL -1. Excellent selectivity toward methiocarb was observed among various pesticides and cationic...