Handheld Crop Pest Sensor Using Binary Catalyst-Loaded Nano-SnO2 Particles for Oxidative Signal Amplification.

In agriculture, pest management is a major challenge. Crop releases volatiles in response to the pest; hence, sensing these volatile signals at a very early stage will ease pest management. Here, binary catalyst-loaded SnO2 nanoparticles of <5 nm were synthesized for the repeated capture and oxidation of the signature volatile and its products to amplify the chemoresistive signal to detect concentrations as low as ≈120 ppb. The sensitivity may be due to the presence of the elements in the Sn-Fe-Pt bond evidenced by extended X-ray absorption fine-structure spectroscopy (EXAFS) that captures and oxidize the volatile without escaping. This strong catalyst may oxidize nontarget volatiles and can cause false signals; hence, a molecular sieve filter has been coupled to ensure high selectivity for the detection ofTuta absolutainfestation in tomato. Finally, with the support of a mobile power bank, the optimized sensor has been assembled into a lightweight handheld device.

Starch wall of urea: Facile starch modification to residue-free stable urea coating for sustained release and crop productivity.

Quick leaching of urea fertilizer encourages different coatings, but achieving a stable coating without toxic linkers is still challenging. Here, the naturally abundant bio-polymer, i.e., starch, has been groomed to form a stable coating through phosphate modification and the support of eggshell nanoparticles (ESN) as a reinforcement agent. The ESN offers a calcium ion binding site for the phosphate to cause bio-mimetic folding. This coating retains hydrophilic ends in the core and gives an excellent hydrophobic surface (water contact angle 123°). Further, the phosphorylated starch+ESN led the coating to release only ∼30 % of the nutrient in the initial ten days and sustained for up to 60 days to show ∼90 % release. The stability of the coating has been attributed to its resistance to major soil factors viz., acidity and amylase degradation. The ESN also increases elasticity, cracking control, and self-repairing capacity by serving as buffer micro-bots. The coated urea enhanced the yield of rice grain by ∼10%.

Phone Camera Nano-Biosensor Using Mighty Sensitive Transparent Reusable Upconversion Paper.

Lycopene, a natural colorant and antioxidant with a huge growing market, is highly susceptible to photo/thermal degradation, which demands real-time sensors. Hence, here a transparent upconversion nanoparticles (UCNPs) strip having 30 mol % Yb, 0.1 mol % Tm, and ß-NaYF4 UCNPs, which shows an intense emission at 475 nm, has been developed. This strip has been found to be sensitive to lycopene with a detection limit as low as 10 nM using a smartphone camera, which is due to static quenching that is confirmed by the lifetime study. In comparison to previous paper strips, here the transparent strip has minimal scattering with maximum sensitivity in spite of not using any metal quenchers. An increase in strip hydrophobicity during the fabrication process complements the strip to selectively permeate and present an extraction-free substitute analysis for chromatography. Hydrophobicity endows the strip with the capability to reuse the strip with ∼100% luminescence recovery.