One-pot biosynthesis of silver nanoparticle using Colocasia esculenta extract: Colorimetric detection of melamine in biological samples

Revolutionizing agriculture: Harnessing nano-innovations for sustainable farming and environmental preservation

The agricultural sector is currently confronted with a significant crisis stemming from the rapid changes in climate patterns, declining soil fertility, insufficient availability of essential macro and micronutrients, excessive reliance on chemical fertilizers and pesticides, and the presence of heavy metals in soil. These numerous challenges pose a considerable threat to the agriculture industry. Furthermore, the exponential growth of the global population has led to a substantial increase in food consumption, further straining agricultural systems worldwide. Nanotechnology holds great promise in revolutionizing the food and agriculture industry, decreasing the harmful effects of agricultural practices on the environment, and improving productivity. Nanomaterials such as inorganic, lipid, and polymeric nanoparticles have been developed for increasing productivity due to their unique properties. Various strategies can enhance product quality, such as the use of nano-clays, nano zeolites, and hydrogel-based materials to regulate water absorption and release, effectively mitigating water scarcity. The production of nanoparticles can be achieved through various methods, each of which has its own unique benefits and limitations. Among these methods, chemical synthesis is widely favored due to the impact that various factors such as concentration, particle size, and shape have on product quality and efficiency. This review provides a detailed examination of the roles of nanotechnology and nanoparticles in sustainable agriculture, including their synthetic methods, and presents an analysis of their associated advantages and disadvantages. To date, there are serious concerns and awareness about healthy agriculture and the production of healthy products, therefore the development of nanotech-enabled devices that act as preventive and early warning systems to identify health issues, offering remedial measures is necessary.

Metal-Organic Framework Fluorescence Sensors for Rapid and Accurate Detection of Melamine in Milk Powder

In this research, a simple, label-free, and ultra-sensitive fluorescent platform based on a metal-organic framework (MOF) has been developed to detect melamine in milk powder. This fluorescence sensor was fabricated from sensitized terbium (Tb)@NH₂-MIL-253 (Al) MOF using a hydrothermal method that involved combining the green emission of Tb (λ_em = 545 nm) with the blue emission of NH₂-MIL-253(Al) MOF (λ_em = 430 nm) under a single excitation wavelength (λ_ex = 335 nm). The fluorescence sensor was then used under optimized conditions (pH = 9.0; sensor concentration = 30 mg/L; response time = 30 s) to quantify melamine in milk powder. The accuracy, sensitivity, and reproducibility of this sensor were established compared to the high-performance liquid chromatography (HPLC) method. The linear range and lower limit of detection (LLOD, computed with 3σ/S) of the sensor were between 40-396.45 nM (equal to 25 µg/kg-0.25 mg/kg) and 40 nM (equal to 25 µg/kg), respectively, which is much less than the maximum residual level (MRL) for the detection of melamine in infant formula (1 mg/kg) and other foods/feeds (2.5 mg/kg). Additionally, the results had good agreement with the HPLC outcomes, suggesting that the NH₂-MIL-253(Al) MOF sensing probe has great precision and repeatability. To conclude, the new fluorescence sensor developed in this study can accurately and sensitively detect melamine in food samples, which may be useful for screening for adulteration of milk powders and other foods.

Synthesis and Characterization of Ferrous and Copper Nanoparticles from E-Waste Using Biological Reduction by Lichen-Associated Bacteria and Their Application in Antifouling Activity

The largest and fastest growing industry in the world is electronic industries and the generation of waste are emerging problem. Electronic wastes are the source of precious metals that contributes 40 to 50 times more than the ore extracted from mines. The recycling of the waste is very important as it can protect the earth's natural resources. There are various methods for recycling e-waste such as chemical, fire, physical, and mechanical method. Currently, chemical treatment is in practice for recycling but, due to the usage of inorganic chemicals, it gives more environmental issues. Therefore, this paper used the biological method to prepare the nanoparticle from e-waste as it is an eco-friendly method. The copper and ferrous nanoparticle was extracted from the e-waste and biologically reduced using lichen-associated bacterial such as Parmotrema tintorum and P. recticulatum. The characteristics of these nanoparticles such as size, shape, and functional group were analyzed using UV, PSA, SEM, and FTIR respectively. The size of the synthesized particle was in the range of 10-100 nm using PSA. At the 2.5% concentration, the synthesis of ferrous nanoparticles was confirmed by the peak value obtained at 430 nm and 540 nm for copper nanoparticles. The antifouling properties of synthesized nanoparticles were analyzed by colliding them with the paint and applying to the iron surface. In recent research, the nanomaterials were able to use to reduce the fouling activity, also prevent harmful effects to the other marine species and the resistance of some microorganisms to antifoulants. This study helps to prevent environmental contaminants by using the copper and ferrous nanoparticle substances synthesized from the e-waste materials with the help of bacterial reduction.

Two-step aggregation of gold nanoparticles based on charge neutralization for detection of melamine by colorimetric and surface-enhanced Raman spectroscopy platform

A colorimetric and surface-enhanced Raman scattering (SERS) signal amplification platform based on 2-step aggregation of gold nanoparticles (AuNP) was constructed for the sensitive detection of melamine. In this study, the positively charged SYBR Green I was used for the first step of aggregation of AuNP, via charge neutralization, to obtain small-sized AuNP aggregates. The positively charged SYBR Green I decreased the negative charges of the surface of AuNP, which was beneficial to the aggregation of AuNP. In addition, the melamine could aggregate AuNP by decreasing the negative charges of the surface of AuNP and self-assemble with each other on the surface of AuNP by hydrogen bonds. Therefore, the second efficient aggregation of small-sized AuNP aggregates could be achieved with melamine at low concentration, resulting in significant signal changes of color and SERS. The sensitivity of a colorimetric (0.60 mg/L) and SERS (0.089 mg/L) platform, based on 2-step aggregation of AuNP, was 15 and 2.2 times higher than that based on 1-step aggregation of AuNP for detecting melamine.

Rapid Detection of Nonprotein Nitrogen Adulterants in Milk Powder Using Point-Scan Raman Hyperspectral Imaging Technology

To develop a rapid detection method for nonprotein nitrogen adulterants, this experiment sets up a set of point-scan Raman hyperspectral imaging systems to qualitatively distinguish and quantitatively and positionally analyze samples spiked with a single nonprotein nitrogen adulterant and samples spiked with a mixture of nine nonprotein nitrogen adulterants at different concentrations (5 × 10-3 to 2.000%, w/w). The results showed that for samples spiked with single nonprotein nitrogen adulterants, the number of pixels corresponding to the adulterant in the region of interest increased linearly with an increase in the analyte concentration, the average coefficient of determination (R 2) was above 0.99, the minimum detection concentration of nonprotein nitrogen adulterants reached 0.010%, and the relative standard deviation (RSD) of the predicted concentration was less than 6%. For the sample spiked with a mixture of nine nonprotein nitrogen adulterants, the standard curve could be used to accurately predict the additive concentration when the additive concentration was greater than 1.200%. The detection method established in this study has good accuracy, high sensitivity, and strong stability. It provides a method for technical implementation of real-time and rapid detection of adulterants in milk powder at the port site and has good application and promotion prospects.

In Situ Functionalization of Silver Nanoparticles by Gallic Acid as a Colorimetric Sensor for Simple Sensitive Determination of Melamine in Milk

A simple and green colorimetric sensing assay strategy for highly efficient determination of melamine has been fabricated, which is based on the redox reaction of gallic acid with Ag+. Monodispersed Ag nanoparticles (AgNPs) were obtained using gallic acid as a reducing and stabilizing agent. However, the aggregate behavior of AgNPs was observed, while the melamine was present in the reaction medium. As a result, the color of the solution changed from vivid yellow to brown, and the density of the color was quantitatively correlated with the melamine concentration. The aggregation of AgNPs could be attributable to the formation of hydrogen bonds between melamine and gallic acid. The designed sensor exhibited a good detection limit of 0.099 μM (0.012 ppm), which was much lower than the safety limit in China (1.0 ppm) and EU (2.0 ppm). Additionally, the sensing assay displayed good selectivity toward melamine over other coexisting substances. Consequently, the proposed colorimetric sensor was successfully used for the determination of melamine detection in raw milk samples.

Ganoderma lucidum inspired silver nanoparticles and its biomedical applications with special reference to drug resistant Escherichia coli isolates from CAUTI

In the search for alternative therapy for infections and other ailments, metallic nanoparticles, mainly silver nanoparticles (AgNPs) synthesized through bioengineered sources are extensively explored. Fungal bioactive compounds and their nanoparticles were reported with the potential biomedical application. A medicinal mushroom Ganoderma lucidum was reported as a repository of rich medicinal properties. In the current study, silver nanoparticles were synthesized using the extracts of G. lucidum and its antimicrobial activity was tested against drug-resistant Escherichia coli isolated from the catheter used for urinary tract infection (CAUTI). The GC-MS study of G. lucidum extracts showed the presence of ethyl acetoacetate ethylene acetal with the highest area percentage of 72.2% and retention time (RT 5873). Pyridine-3-ol is the second primary compound with a peak height of 6.44% and a retention time of 2.143. The third compound is l,4-Dioxane-2,3-diol, with an area of 8.09% and RT 5450. Butylated Hydroxy Toluene [BHT] is the fourth major compound with an area of 3.32%, and 9-Cedranone constitutes the fifth position in occupying the area percentage [1.88] and height 1.56%. Pyrrole is the sixth primary compound registering an area size of 0.96% and height 2.06%. The AgNPs synthesized using G. lucidum extract were in size range 23 and 58 nm as per SEM analysis and within the range wavelength 0.556-0.796 nm as per UV-Vis spectral study. FTIR Spectroscopy and X-ray diffraction analysis (XRD) were made to characterize the formed nanoparticles. The AgNPs synthesized effectively inhibited the growth of E. coli isolated from catheter-associated urinary tract infection and showed resistance to many drugs. The antioxidant potential of the synthesized nanoparticles assessed using DPPH radical scavenging activity, EC50 (µg/ml), and ARP data showed that the prepared nanoparticles were more potent in free radical scavenging activity than the standard quercetin. The cytotoxicity effect of Ag-NPs on breast cancer cell line- MDA-MB-231 confirmed its anticancer potential. The half-maximal inhibitory concentration (IC50) of Ag-NPs to inhibit 50% of the tumor was 9.2 g/mL. The synthesized GL-AgNPs was exhibited a multifocal biomedical potential.