Development of aptamer surface-enhanced Raman spectroscopy sensor based on Fe3O4@Pt and Au@Ag nanoparticles for the determination of acetamiprid

As a common chlorinated nicotinic pesticide with high insecticidal activity, acetamiprid has been widely used for pest control. However, the irrational use of acetamiprid will pollute the environment and thus affect human health. Therefore, it is crucial to develop a simple, highly sensitive, and rapid method for acetamiprid residue detection. In this study, the capture probe (Fe3O4@Pt-Aptamer) was connected with the signal probe (Au@DTNB@Ag CS-cDNA) to form an assembly with multiple SERS-enhanced effects. Combined with magnetic separation technology, a SERS sensor with high sensitivity and stability was constructed to detect acetamiprid residue. Based on the optimal conditions, the SERS intensity measured at 1333 cm-1 is in relation to the concentration of acetamiprid in the range 2.25 × 10-9-2.25 × 10-5 M, and the calculated limit of detection (LOD) was 2.87 × 10-10 M. There was no cross-reactivity with thiacloprid, clothianidin, nitenpyram, imidacloprid, and chlorpyrifos, indicating that this method has good sensitivity and specificity. Finally, the method was applied to the detection of acetamiprid in cucumber samples, and the average recoveries were 94.19-103.58%, with RSD < 2.32%. The sensor can be used to analyse real samples with fast detection speed, high sensitivity, and high selectivity.

Decoration of Au Nanoparticles over LaFeO3: A High Performance Electrocatalyst for Total Water Splitting

Electrocatalytic water splitting has emerged as a promising approach for clean and sustainable hydrogen production. The LaFeO3 perovskite structure exhibits intriguing properties such as mixed ionic-electronic conductivity, high stability, and abundant active sites for electrocatalysis. However, its OER and HER activities are limited by the sluggish kinetics of these reactions. To overcome this limitation, Au nanoparticles (NPs) are decorated onto the surface of LaFeO3 through a facile synthesis method. The Au NPs on the LaFeO3 surface provide additional active sites for water splitting reactions, promoting the adsorption and activation of water molecules. The presence of Au enhances the charge transfer kinetics via the heterostructure between Au NPs and LaFeO3 and facilitates electron transport during the OER and HER process. The catalyst requires only 318 and 199 mV as overpotential to attain a 50 mA cm-2 current density in 1 M KOH solution. Our results demonstrate that the Au@LaFeO3 catalyst exhibits significantly improved electrocatalytic activity compared to pure LaFeO3 and other catalysts reported in the literature. The enhanced performance is attributed due to the synergistic effects between Au NPs and LaFeO3, including an increased surface area, improved conductivity, and optimized surface energetics. Overall, the Au-decorated LaFeO3 catalyst presents a promising candidate for efficient electrocatalytic water splitting, providing a pathway for sustainable hydrogen production. The insights gained from this study contribute to the development of advanced catalysts for renewable energy technologies and pave the way for future research in the field of electrochemical water splitting.

Fabrication of highly stable platinum organosols over DNA-scaffolds for enriched catalytic and SERS applications

The use of nanomaterials (NMs) in various applications via multidisciplinary approaches is highly necessary in this era. In this line, the impact of noble metals in organic media for both catalysis and surface-enhanced Raman spectroscopic (SERS) studies is most interesting and also has a wider scope in various fields. Nonetheless, the catalytic reduction of aromatic nitro compounds is difficult with poor solubility in aqueous media, and reduction also is less feasible in the absence of noble metal-based catalysts. Thus, the choice of noble metal-based catalysts for the catalytic reduction of nitro compounds in organic media is one of the emerging methods with high selectivity towards products. Moreover, the superior catalytic activity of Pt NPs provides a higher rate constant value with a low dielectric constant of organic solvents. Herein, for the first time, we synthesised highly stable metallic Pt nanoparticles (NPs) anchored on bio-scaffold deoxyribonucleic acid (DNA) for two different applications. The advantage of highly controlled nucleation of NPs over DNA in organic media results in a spherical morphology with a particle diameter of 2.47 ± 2.11 nm and 2.84 ± 1.14 nm. A stable colloidal solution of Pt NPs was prepared by a simple wet chemical sodium borohydride reduction method within 15 minutes from the start of the reaction. Two sets of Pt NPs were synthesised by varying the molar ratio of the concentration of DNA to PtCl4 concentration and were named Pt@DNA (0.05 M) and Pt@DNA (0.06 M), respectively. The prepared Pt@DNA was effectively studied for two potential applications such as the SERS studies and catalytic reduction of nitro compounds. In catalysis, a higher catalytic rate was observed in the case of 4-nitrophenol (4-NP) at a rate of 8.43 × 10-2 min-1. In the SERS study, the reduction of the interparticle distance to below 5 nm facilitates the creation of a large number of hot spots for probe detection. Here, we used 10-3 M methylene blue (MB) as a probe molecule, and the enhancement factor (EF) value was calculated at different concentrations ranging from 10-3 M to 10-6 M. The highest enhancement factor (EF) value obtained was 2.91 × 105 for Pt@DNA (0.05 M). The as-synthesised stable Pt@DNA organosol can be exploited for other potential applications related to energy, sensor and medicinal fields in the near future.

Prospects in interfaces of biomolecule DNA and nanomaterials as an effective way for improvising surface enhanced Raman scattering: A review

Surface Enhanced Raman Scattering (SERS) is a field of research that has shown promising application in the analysis of various substrate molecules by means of rough metallic surfaces. In directing the enhancement of substrate molecules in micro and nano-molar concentrations, plasmonic coupling of metal nanoparticles (NPs), morphology of metal NPs and the closely arrangement of rough metal surfaces that produces 'hot spots' can effectively increase the so-called enhancement factor (EF) that will be applicable in various fields. As the mechanistic aspects are still not clear, research has been triggered all over the world for the past two decades to have a clear understanding in chemical and electromagnetic effects. As the reproducibility of intensity of signals at low concentrations of probe molecules is of a big concern, metal NPs with various scaffolds were prepared and recently bio-molecule, DNA has been studied and showed promising advantages. This review first time highlights metal NPs with DNA interface as an effective rough metallic surface for SERS with high intensity and also with better reproducibility. Based on this review, similar kinds of scaffolds like DNA can be used to further analyze SERS activities of various metal NPs with different morphologies to have high intense signals at low concentrations of probe molecules.

Developments in DNA metallization strategies for water splitting electrocatalysis: A review

The biomolecule DNA with the presence of different functionalities found to interact with different kinds of metal ions and show relatively higher stability over a long period of time when optimized appropriately. With the presence of A-T and G-C pairs, sugar moieties, phosphate functional groups and the double-helical structure, it can assemble both cationic and anionic species and forms a perfect metal-DNA self-assembly. Depending upon the aspect ratio of metal-DNA self-assemblies, metal content and their morphological outcomes, they could deliver variance in the catalytic activities. Such differences can be brought out by varying the synthesis reaction parameters focusing on a specific electrocatalytic application. In this review, recent developments in DNA metallization is elaborated first highlighting the underlying interactions between DNA and cationic/anionic species of various metals following which application of metal-DNA assemblies in electrocatalytic water oxidation and reduction are discussed critically. Knowledge provided in this review thus acts as the guide to various DNA metallization strategies and their subsequent application to water electrolysis for hydrogen generation.

Electrostatically PEGylated DNA enables salt-free hybridization in water

Chemically modified nucleic acids have long served as a very important class of bio-hybrid structures. In particular, the modification with PEG has advanced the scope and performance of oligonucleotides in materials science, catalysis and therapeutics. Most of the applications involving pristine or modified DNA rely on the potential of DNA to form a double-stranded structure. However, a substantial requirement for metal-cations to achieve hybridization has restricted the range of applications. To extend the applicability of DNA in salt-free or low ionic strength aqueous medium, we introduce noncovalent DNA-PEG constructs that allow canonical base-pairing between individually PEGylated complementary strands resulting in a double-stranded structure in salt-free aqueous medium. This method relies on grafting of amino-terminated PEG polymers electrostatically onto the backbone of DNA, which results in the formation of a PEG-envelope. The specific charge interaction of PEG molecules with DNA, absolute absence of metal ions within the PEGylated DNA molecules and formation of a double helix that is significantly more stable than the duplex in an ionic buffer have been unequivocally demonstrated using multiple independent characterization techniques.