The development of green and scalable syntheses for the preparation of size-and shape-controlled metal nanocrystals is of high interest in many areas, including catalysis, electrocatalysis, nanomedicine, and electronics. In this work, a new synthetic approach based on the synergistic action of physical parameters and reagents produces size-tunable octahedral Pt nanocrystals, without the use of catalyst-poisoning reagents and/or difficult-to-remove coatings. The synthesis requires sodium citrate, ascorbic acid, and fine control of the reduction rate in aqueous environment. Pt octahedral nanocrystals with particle size as low as 7 nm and highly developed {111} facets have been achieved, as demonstrated by transmission electron microscopy, X-ray diffraction, and electrochemical methods. The absence of sticky molecules together with the high quality of the surface renders these nanocrystals ideal candidates in electrocatalysis. Notably, 7 nm bismuth-decorated octahedral nanocrystals exhibit superior performance for the electro-oxidation of formic acid in terms of both specific and mass activities.
Early diagnostics and point-of-care (POC) devices can save people’s lives or drastically improve their quality. In particular, millions of diabetic patients worldwide benefit from POC devices for frequent self-monitoring of blood glucose. Yet, this still involves invasive sampling processes, which are quite discomforting for frequent measurements, or implantable devices dedicated to selected chronic patients, thus precluding large-scale monitoring of the globally increasing diabetic disorders. Here, we report a non-invasive colorimetric sensing platform to identify hyperglycemia from saliva. We designed plasmonic multibranched gold nanostructures, able to rapidly change their shape and color (naked-eye detection) in the presence of hyperglycemic conditions. This “reshaping approach” provides a fast visual response and high sensitivity, overcoming common detection issues related to signal (color intensity) losses and bio-matrix interferences. Notably, optimal performances of the assay were achieved in real biological samples, where the biomolecular environment was found to play a key role. Finally, we developed a dipstick prototype as a rapid home-testing kit.
In this study, we describe a monolithic and fully integrated paper-based device for the simultaneous detection of three prognostic biomarkers in saliva. The pattern of the proposed multiplexed device is designed with a central sample deposition zone and three identical arms, each containing a pre-treatment and test zone. Its one-step fabrication is realized by CO2 laser cutting, providing remarkable parallelization and rapidity (ca. 5 s/device). The colorimetric detection is based on the sensitive and selective target-induced reshaping of plasmonic multibranched gold nanoparticles, which exhibit a clear spectral shift (and blue-to-pink color change) in case of non-physiological concentrations of the three salivary biomarkers. A rapid and multiplexed naked-eye or smartphone-based readout of the colorimetric response is achieved within 10 min. A prototype kit for POCT testing is also reported, providing robustness and easy handling of the device.
Making frequent large-scale screenings for several diseases economically affordable would represent a real breakthrough in healthcare. One of the most promising routes to pursue such an objective is developing rapid, non-invasive, and cost-effective home-testing devices. As a first step toward a diagnostic revolution, glycemia self-monitoring represents a solid base to start exploring new diagnostic strategies. Glucose self-monitoring is improving people’s life quality in recent years; however, current approaches still present vast room for improvement. In most cases, they still involve invasive sampling processes (i.e., finger-prick), quite discomforting for frequent measurements, or implantable devices which are costly and commonly dedicated to selected chronic patients, thus precluding large-scale monitoring. Thanks to their unique physicochemical properties, nanoparticles hold great promises for the development of rapid colorimetric devices. Here, we overview and analyze the main instrument-free nanosensing strategies reported so far for glucose detection, highlighting their advantages/disadvantages in view of their implementation as cost-effective rapid home-testing devices, including the potential use of alternative non-invasive biofluids as samples sources.
We present a fast and sensitive nanosensor that can detect organic mercury, exploiting the combination of the catalytic and plasmonic properties of gold nanoparticles (AuNPs). The method is one‐step and completely instrument‐free, and has a colorimetric readout clearly detectable by simple visual inspection. The AuNPs catalyze efficient organic mercury reduction to the metallic form (Hg0), allowing its nucleation and amalgam formation on particle surface, with consequent aggregation‐induced plasmon shift. This leads to very rapid (1 min) and specific colorimetric detection of mercury species. The achieved limit of detection (20 ppb) is compliant with current regulatory limits in food.
Counterfeiting is a worldwide issue affecting many industrial sectors, ranging from specialized technologies to retail market, such as fashion brands, pharmaceutical products, and consumer electronics. Counterfeiting is not only a huge economic burden (>$ 1 trillion losses/year), but it also represents a serious risk to human health, for example, due to the exponential increase of fake drugs and food products invading the market. Considering such a global problem, numerous anticounterfeit technologies have been recently proposed, mostly based on tags. The most advanced category, based on encryption and cryptography, is represented by physically unclonable functions (PUFs). A PUF tag is based on a unique physical object generated through chemical methods with virtually endless possible combinations, providing remarkable encoding capability. However, most methods adopted nowadays are based on expensive and complex technologies, relying on instrumental readouts, which make them not effective in real-world applications. To achieve a simple yet cryptography-based anticounterfeit method, herein we exploit a combination of nanotechnology, chemistry, and artificial intelligence (AI). Notably, we developed platinum nanocatalyst-enabled visual tags, exhibiting the properties of PUFs (encoding capability >10300) along with fast (1 min) ON/OFF readout and full reversibility, enabling multiple onsite authentication cycles. The development of an accurate AI-aided algorithm powers the system, allowing for smartphone-based PUF authentications.
Nowadays, there is an increasing interest in Point-of-care (POC) devices for the noninvasive glucose assessment. Despite the recent progress in glucose self-monitoring, commercially available devices still use invasive samples such as blood or interstitial fluids, and they are not equipment-free and affordable for the whole population. Here, we report a fully integrated strip test for the semi-quantitative detection of glucose in whole saliva. The colorimetric mechanism consists of an enzyme-mediated reshaping of multibranched gold nanoparticles (MGNPs) into nanospheres with an associated plasmonic shift and consequent blue-to-red color change, clearly detectable in less than 10 min.
We present af ast and sensitive nanosensor that can detect organic mercury,e xploiting the combination of the catalytic and plasmonic properties of gold nanoparticles (AuNPs). The method is one-step and completely instrument-free,and has acolorimetric readout clearly detectable by simple visual inspection. The AuNPs catalyze efficient organic mercury reduction to the metallic form (Hg 0 ), allowing its nucleation and amalgam formation on particle surface,w ith consequent aggregation-induced plasmon shift. This leads to very rapid (1 min) and specific colorimetric detection of mercury species.T he achieved limit of detection (20 ppb) is compliant with current regulatory limits in food.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under https://doi.
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