Colorimetric As (V) detection based on S-layer functionalized gold nanoparticles

Nanomaterial-based optical colorimetric sensors for rapid monitoring of inorganic arsenic species: a review

Health concerns about the toxicity of arsenic compounds have therefore encouraged the development of new analytical tools for quick monitoring of arsenic in real samples with improved sensitivity, selectivity, and reliability. An overview of advanced optical colorimetric sensor techniques for real-time monitoring of inorganic arsenic species in the environment is given in this review paper. Herein, several advanced optical colorimetric sensor techniques for arsenite (As+3) and arsenate (As+5) based on doping chromogenic dyes/reagents, biomolecule-modified nanomaterials, and arsenic-binding ligand tethered nanomaterials are introduced and discussed. This review also highlights the benefits and limitations of the colorimetric sensor for arsenic species. Finally, prospects and future developments of an optical colorimetric sensor for arsenic species are also proposed. For future study in this sector, particularly for field application, authors recommend this review paper will be helpful for readers to understand the design principles and their corresponding sensing mechanisms of various arsenic optical colorimetric sensors.

Identification of heavy metal ions from aqueous environment through gold, Silver and Copper Nanoparticles: An excellent colorimetric approach

Heavy metal pollution has become a severe threat to human health and the environment for many years. Their extensive release can severely damage the environment and promote the generation of many harmful diseases of public health concerns. These toxic heavy metals can cause many health problems such as brain damage, kidney failure, immune system disorder, muscle weakness, paralysis of the limbs, cardio complaint, nervous system. For many years, researchers focus on developing specific reliable analytical methods for the determination of heavy metal ions and preventing their acute toxicity to a significant extent. The modern researchers intended to utilize efficient and discerning materials, e.g. nanomaterials, especially the metal nanoparticles to detect heavy metal ions from different real sources rapidly. The metal nanoparticles have been broadly utilized as a sensing material for the colorimetric detection of toxic metal ions. The metal nanoparticles such as Gold (Au), Silver (Ag), and Copper (Cu) exhibited localized plasmon surface resonance (LPSR) properties which adds an outstanding contribution to the colorimetric sensing field. Though, the stability of metal nanoparticles was major issue to be exploited colorimetric sensing of heavy emtal ions, but from last decade different capping and stabilizing agents such as amino acids, vitmains, acids and ploymers were used to functionalize the metal surface of metal nanoparticles. These capping agents prevent the agglomeration of nanoparticles and make them more active for prolong period of time. This review covers a comprehensive work carried out for colorimetric detection of heavy metals based on metal nanoparticles from the year 2014 to onwards.

Recent Advances in Colorimetric Detection of Arsenic Using Metal-Based Nanoparticles

Nowadays, arsenic (III) contamination of drinking water is a global issue. Laboratory and instrument-based techniques are typically used to detect arsenic in water, with an accuracy of 1 ppb. However, such detection methods require a laboratory-based environment, skilled labor, and additional costs for setup. As a result, several metal-based nanoparticles have been studied to prepare a cost-effective and straightforward detector for arsenic (III) ions. Among the developed strategies, colorimetric detection is one of the simplest methods to detect arsenic (III) in water. Several portable digital detection technologies make nanoparticle-based colorimetric detectors useful for on-site arsenic detection. The present review showcases several metal-based nanoparticles that can detect arsenic (III) colorimetrically at a concentration of ~0.12 ppb or lower in water. A literature survey suggests that biomolecule-based metal nanoparticles could serve as low-cost, facile, susceptible, and eco-friendly alternatives for detecting arsenic (III). This review also describes future directions, perspectives and challenges in developing this alternative technology, which will help us reach a new milestone in designing an effective arsenic detector for commercial use.

Bio-Nanocarriers for Lung Cancer Management: Befriending the Barriers

Lung cancer is a complex thoracic malignancy developing consequential to aberrations in a myriad of molecular and biomolecular signaling pathways. It is one of the most lethal forms of cancers accounting to almost 1.8 million new annual incidences, bearing overall mortality to incidence ratio of 0.87. The dismal prognostic scenario at advanced stages of the disease and metastatic/resistant tumor cell populations stresses the requisite of advanced translational interdisciplinary interventions such as bionanotechnology. This review article deliberates insights and apprehensions on the recent prologue of nanobioengineering and bionanotechnology as an approach for the clinical management of lung cancer. The role of nanobioengineered (bio-nano) tools like bio-nanocarriers and nanobiodevices in secondary prophylaxis, diagnosis, therapeutics, and theranostics for lung cancer management has been discussed. Bioengineered, bioinspired, and biomimetic bio-nanotools of considerate translational value have been reviewed. Perspectives on existent oncostrategies, their critical comparison with bio-nanocarriers, and issues hampering their clinical bench side to bed transformation have also been summarized.

Development of a Gold Nanoparticle-Based Colorimetric Sensor for Water for Injection At-Line Impurity Testing

The best-known rapid test using gold nanoparticles (AuNPs) is the human chorionic gonadotropin pregnancy test. AuNPs are a powerful tool in point-of-care testing because of their flexibility, modifiability, and visibility. Here, we report a method to detect impurities for at-line process control in water-for-injection (WFI) manufacturing through the example of endotoxins. If a distinct concentration of these amphipathic molecules, originated from gram-negative bacteria, enters the human body, it will result in septic shock, followed by organ failure and possibly death. Every fluid given parenterally is subject to strict regulatory requirements and therefore endotoxin testing. Through use of traditional methods like the limulus amebocyte lysate (LAL) test, it takes more than 2 h to complete. With the presented method, one-fifth of the sample volume is sufficient compared with the LAL test. Once the assay components have been mixed, the result can be interpreted visually within 2 min without the use of further instruments.

A novel electrochemical sensor based on double-walled carbon nanotubes and graphene hybrid thin film for arsenic(V) detection

In this work, we demonstrate the preparation of hybrid thin films based on double-walled carbon nanotubes and graphene for electrochemical sensing applications. The hybrid films were synthesized on polycrystalline copper foil by thermal chemical vapor deposition under low pressure. This carbonaceous hybrid film has exhibited high transparency with a transmittance of 94.3 %. The occurrence of this hybrid material on the electrode surface of screen-printed electrodes was found to increase electroactive surface area by 1.4 times, whereas electrochemical current was enhanced by 2.4 times. Such a highly transparent and conductive hybrid film was utilized as a transducing platform of enzymatic electrochemical arsenic(V) sensor. The as-prepared sensor shows the linear detection of arsenic(V) in the range from 1 to 10 ppb, with a limit of detection as low as 0.287 ppb. These findings provide a promising approach to develop new multifunctional electrochemical sensing systems for environmental monitoring and biomedical diagnostics.

A simple paper-based approach for arsenic determination in water using hydride generation coupled with mercaptosuccinic-acid capped CdTe quantum dots

This research aims to develop a simple paper-based device for arsenic detection in water samples where a hydride generation technique coupled with mercaptosuccinic acid-capped CdTe quantum dots (MSA-CdTe QDs) as a detection probe was applied to the detection system. MSA-CdTe QDs were coated on a paper strip, inserted into the cover cap of a reaction bottle, to react with the developed arsine gas. Fluorescent emission of the QDs was quenched upon the presence of arsenic in solutions, whereby only a small amount of the MSA-CdTe QDs was required. The excitation and emission wavelengths for fluorescent detection were 278.5 nm and 548.5 nm, respectively. The proposed system provided a limit of detection of 0.016 mg L-1 and a limit of quantitation of 0.053 mg L-1, and a detection range of 0.05-30.00 mg L-1. In addition, the tolerance level of the detection approach to interference by other vapor-generated species was successfully improved by placing another paper strip coated with a solution of saturated lead acetate in front of the detection paper strip. This developed approach offered a simple and fast, yet accurate and selective detection of arsenic contaminated in water samples. In addition, the mechanism of fluorescent quenching was also proposed.

S-layer protein-AuNP systems for the colorimetric detection of metal and metalloid ions in water

Bacterial surface layer proteins (S-layer) possess unique binding properties for metal ions. By combining the binding capability of S-layer proteins with the optical properties of gold nanoparticles (AuNP), namely plasmonic resonance, a colorimetric detection system for metal and metalloid ions in water was developed. Eight S-layer proteins from different bacteria species were used for the functionalization of AuNP. The thus developed biohybrid systems, AuNP functionalized with S-layer proteins, were tested with different metal salt solutions, e.g. Indium(III)-chloride, Yttrium(III)-chloride or Nickel(II)-chloride, to determine their selective and sensitive binding to ionic analytes. All tested S-layer proteins displayed unique binding affinities for the different metal ions. For each S-layer and metal ion combination markedly different reaction patterns and differences in concentration range and absorption spectra were detected by UV/vis spectroscopy. In this way, the selective detection of tested metal ions was achieved by differentiated analysis of a colorimetric screening assay of these biohybrid systems. A highly selective and sensitive detection of yttrium ions down to a concentration of 1.67 × 10^-5 mol/l was achieved with S-layer protein SslA functionalized AuNP. The presented biohybrid systems can thus be used as a sensitive and fast sensor system for metal and metalloid ions in aqueous systems.

S-Layer Protein-Based Biosensors

The present paper highlights the application of bacterial surface (S-) layer proteins as versatile components for the fabrication of biosensors. One technologically relevant feature of S-layer proteins is their ability to self-assemble on many surfaces and interfaces to form a crystalline two-dimensional (2D) protein lattice. The S-layer lattice on the surface of a biosensor becomes part of the interface architecture linking the bioreceptor to the transducer interface, which may cause signal amplification. The S-layer lattice as ultrathin, highly porous structure with functional groups in a well-defined special distribution and orientation and an overall anti-fouling characteristics can significantly raise the limit in terms of variety and the ease of bioreceptor immobilization, compactness of bioreceptor molecule arrangement, sensitivity, specificity, and detection limit for many types of biosensors. The present paper discusses and summarizes examples for the successful implementation of S-layer lattices on biosensor surfaces in order to give a comprehensive overview on the application potential of these bioinspired S-layer protein-based biosensors.

Seed-mediated grown silver nanoparticles as a colorimetric sensor for detection of ascorbic acid

A simple and sensitive approach was demonstrated for detection of ascorbic acid (AA) based on seed-mediated growth of silver nanoparticles (Ag NPs). According to the seeding strategy, silver ions existing in the growth solution were reduced to silver atoms on the surface of silver seeds via redox reaction between silver ions and AA. This process -led to appear an absorption band in near 420nm owing to the localized surface plasmon resonance peak of the generated Ag NPs. This change in absorption spectra of Ag NPs caused a change in color of the mixture from colorless to yellow. It was found that the changes in absorption intensity at 420nm have a good relationship with the concentration of AA. Also, detection of AA was achieved through the established colorimetric sensor in the range of 0.25-25μM with detection limit of 0.054μM. Moreover, the selectivity of the method was evaluated with considering potential interferences. The method showed high selectivity toward AA rather than potential interferences and coexisted molecules with AA. It was successfully applied for detection and determination of AA in pharmaceutical tablets and commercial lemonade.

Simple and fast colorimetric detection of inorganic arsenic selectively adsorbed onto ferrihydrite-coated silica gel using silver nanoplates

The optical detection for inorganic arsenic (As) semi-quantitative determination is presented by using silver nanoplates (AgNPls). The color of AgNPs is immediately changed in the presence of As(III) and As(V) with the same sensitivity. To improve the selectivity of AgNPls for As detection, ferrihydrite-coated silica gel (SiO2-Fh) was specifically exploited as adsorbent for arsenic prior to As detection by AgNPls. The developed method provides the detection limit of 0.5ppm with the detection range between 0.5ppm and 30.0ppm for As determination observed with naked eye, and allows to determine total inorganic arsenic. This is the first report of As detection approach combining As removal technology together with nanotechnology. This combined technique provides a rapid, sensitive and selective method for monitoring As levels in aqueous samples, and can be employed as a testing field kit to screen arsenic contamination outside of a laboratory.

Colorimetric detection based on localised surface plasmon resonance of gold nanoparticles: Merits, inherent shortcomings and future prospects

Localised surface plasmon resonance (LSPR) of gold nanoparticles (AuNPs) has been exploited for two decades in analytical science and has proven to be a powerful tool for the detection of various kinds of substances including small molecules, ions, macro biomolecules and microbes. Detection can be performed by visual colour change observations, photometry or resonance light scattering. A wide range of applications have been studied in the areas of environmental, pharmaceutical and biological analysis and clinical diagnosis. In this article, some fundamental aspects and important applications involving LSPR of AuNPs are reviewed. Several inherent shortcomings of these techniques and possible strategies to circumvent them are discussed.