SnO2-xNx based tpod nanostructure for SARS-CoV2 spike protein detection.

The worldwide spreading of severe acute respiratory syndrome SARS-CoV2 pandemic, a massive setback to every human being. In response to strategies actions against Covid-19 spreading many detection, prevention, and post-measures are being studied in large capacities. Association of SARS-CoV2 with ACE2 is well acknowledged and used for developing point-of-care detection kits. Recently, cases and studies have surfaced showing relation of ACE I/D polymorphism with spreading of SARS-CoV2 and highlighted a slip section towards detection and these studies show specificity with older males, high diabetes, and hypertension. To address the raised concern, we report synthesis of unique SnO2-xNx tpod nanostructure, showing affirmative attachment to both ACE1 and ACE2 efficiently. The attachment is examined in different ratios and studied with µ-Raman spectroscopy. The tpod nanostructure has served with its signature raman signals and used as probe for detection of SARS-CoV2 spike protein (S1). The linearity response for tpod raman signal at 630.4 cm-1 shows R2 0.9705, comparatively peak 1219.13 cm-1 show R2 0.9865 and calculated limit of detection of 35 nM.

"Synergistic effect" based novel and ultrasensitive approach for the detection of serotonin using DEM-modulated bimetallic nanosheets.

Neurotransmitters have been of immense scientific interest due to their importance as human-health biomarkers. Several reports suggest necessary improvisations in the sensing capabilities of these neurotransmitters. Herein, the authors report a novel synthesis methodology for bimetallic aluminum-tungsten (Al-W) nanosheets, with the hybrid nanostructure showing high specificity toward serotonin neurotransmitters. The inspiration to design hybrid metallic nanosheets depends on the inherited optical properties of the parent precursors. The interstate conversion (ISC) between Al-W nanosheets promoted photoluminescent behavior with serotonin. The PL study shows that serotonin drastically enhanced λem at 335 nm. The importance of emission below the visible spectrum is to modulate any possible aggregation-induced emissions, which earlier troubled analytical chemists. The understanding of the selective detection of serotonin from a group of similar neurotransmitters is discussed with nanomolar quantification. The quantified detection limit using Al-W nanosheets is 0.05 nm with high linearity (R2 = 0.9906). Furthermore, real-world quantification studies have been performed on human urine and serum samples with R2 of 0.9938 and 0.9801, respectively.

Photoluminescent hydrophilic cyclodextrin-stabilized cysteine-protected copper nanoclusters for detecting lysozyme.

Lysozyme (LYZ) sensors have attracted increased attention because rapid and sensitive detection of LYZ is highly desirable for various diseases associated with humans. In this research, we designed L-cysteine-protected ultra small photoluminescent (PL) copper nanoclusters (CuNCs) conjugated with ß-cyclodextrin (ß-CD) for rapid detection of LYZ in human serum samples at room temperature. The proposed ß-CD-CuNCs exhibited excellent water solubility, ultrafine size, good dispersion, bright photoluminescence, and good photostability. The ß-CD-CuNCs exhibit an excitation and emission maximum at 370 nm and 492 nm, respectively, with an absolute quantum yield (QY) of 54.6%. ß-CD-CuNCs showed a fluorescence lifetime of 12.7 ns. The addition of LYZ would result in PL quenching from ß-CD-CuNCs. The lowest detectable LYZ concentration was 50 nM for the naked eye and the limit of detection (LOD) and limit of quantification (LOQ) were 0.36 nM and 1.21 nM, respectively, by emission measurement observed in the LYZ concentration range from 30 to 100 nM. It is important to note that the PL ß-CD-CuNC strategy possessed great selectivity toward LYZ relative to other biomolecules. The proposed nanosensor was efficiently applied to determine the LYZ level in human serum sample average recoveries from 96.15 to 104.05% and relative standard deviation (RSD) values lower than 3.0%. Moreover, the proposed sensing system showed many advantages, including high speed, high sensitivity, high selectivity, low cost, and simple preparation.

The emergence of red fluorescence from two-dimensional nitrogenated-stanene oxide nanosheets.

The instigation of fluorescence in 2D metal oxide nanosheets is a daunting task to achieve. In the present work, we have synthesized bright red fluorescent stanene oxide (rStNS nanosheets) using an exceptionally simple method. Tin(ii) chloride added to a complex solvent (non-aqueous solution) of acetone and acetonitrile was sonicated and incubated at ambient temperature for ∼six days. After three days (72 h), the solution turned light yellow with bright red fluorescence; this is possible due to interactions between Sn and nitrogen atoms in a nanoscale environment. The emission from rStNS nanosheets (λex = 370 nm) covered a broad range of the optical spectrum (with a prominent peak at 590 nm). Interestingly, after day five, the colour of the solution became darker, and the colour of fluorescence changed from red to green (gStNS nanosheets).

Electrocatalytic synthesis of black tin oxide nanomaterial as photothermal agent for cancer therapy.

Photothermal therapy (PTT) is among the popular approach for treating solid tumours. The rapid killing of cancer cells under the influence of infrared radiation by a rapid increase in the temperature of the remote area now demands external agents with high photothermal transduction efficiency (PTE). Despite their improved PTE, black nanomaterials such as black phosphorus and titanium oxide are unable to meet the challenges in the physiological conditions. To address this major concern, we have developed black tin oxide (bSnO) with enhanced capabilities to respond in the physiological milieu. To make the synthesis cost-effective and eco-friendly, we have used electrochemical oxidation at 5 V and 100 mA to achieve ∼15 nm nanoparticle of bSnO. The as-synthesized bSnO exhibited high NIR absorption as well as high photothermal transduction efficiency. To circumvent the low aqueous solubility and photostability, bSnO was functionalized with polyethyleneimine (PEI). Upon exposure to 808 nm laser for ∼8-10 min, the temperature of the bSnO@PEI solution reached ∼58.5 °C. PTE of bSnO@PEI was calculated to be 51.2%. Owing to its high biological compatibility, tin offers relatively better stability when exposed to cancer cells in vitro and in vivo. In comparison to other black nanomaterials, bSnO@PEI was found to exhibit better response under NIR irradiance for non-invasive photothermal therapy of cancer.

Synthesis of fluorescent molybdenum nanoclusters at ambient temperature and their application in biological imaging.

We introduce for first time a facile protocol for the rapid synthesis of a molybdenum nanoclusters (MoNCs) at room temperature using thiolated dithiothreitol (DTT) as capping agents. The initial fluorescence from the MoNCs is observed in 30 min and further intensified in 48 h. The mean diameter of nanoclusters was found to be 1.5 nm with -77 mV zeta potential. The nanoclusters have good stability in all tested pH ranges, especially between pH 7 and 10. This property makes the nanomaterial to be ideal for many types of possible biological/biomedicine applications such as drug delivery or biological imaging. The quantum yield of thiolated MoNCs was calculated to be 59% which is higher than the noble metal nanoclusters reported earlier. The mechanism of formation of MoNCs was investigated using the UV-Vis spectroscopy and cyclic voltammetry. Owing to these characteristics, MoNCs were used for imaging of HaCaT and A549 cancer cells. The current approach on novel synthesis of MoNCs is found to be a superior alternative to conventional/popular MoS2 based on the method of synthesis, particle size, and fluorescence quantum yield. The current approach on the MoNCs has created a new platform for future biomedicine applications.