Nitric Oxide/Peroxynitrite Redox Imbalance in Endothelial Cells Measured with Amperometric Nanosensors

The cytoprotective messenger nitric oxide (NO) and cytotoxic peroxynitrite (ONOO-) are the main components of oxidative stress and can be generated by endothelial cells. A tandem of electrochemical nanosensors (diameter 200-300 nm) were used to measure, in situ, the balance between NO and ONOO-produced by human umbilical vein endothelial cells (HUVEC’s). The amperometric nanosensors were placed 5 ± 2 μm from the surface of the endothelial cells and the concentration of NO and ONOO- was measured at 630 mV and -300 mV (vs Ag/AgCl) respectively. Normal, functional, endothelial cells produced maximal 450 ± 25 nmol.L-1 of NO and 180 ± 15 nmol.L-1 of ONOO- in about 3 s, after stimulation with calcium ionophore. The in situ measurements of NO and ONOO- were validated using nitric oxide synthase inhibitor L-NMMA, ONOO- scavenger Mn(III) porphyrin, and superoxide dismutase (PEG-SOD). The ratio of NO concentration to ONOO- concentration ([NO]/[ONOO-]) was introduced for quantification of both, the redox balance and the level of the nitroxidative stress in the endothelium. [NO]/[ONOO-] was 2.7 ± 0.1 in a functional endothelium. The model of the dysfunctional endothelium was made by the treatment of HUVEC’s with angiotensin II for 20 min. Dysfunctional HUVEC’s produced only 115 ± 15 nmol.L-1 of NO, but generated a significantly higher concentration of ONOO- of 490 ± 30 nmol.L-1. The [NO]/[ONOO-] ratio decreased to 0.23 ± 0.14 in the dysfunctional endothelium. Electrochemical nanosensors can be effectively used for in situ monitoring of changing levels of nitroxidative/ oxidative stress, and may be useful in early medical diagnosis of the cardiovascular system.

Current trends in nanomaterials-mediated biosensing platforms and signal amplification strategies for antibiotics detection in dairy products

Dairy products have become one of the most prevalent daily foods worldwide,but safety concerns are rising.In dairy farming,unscrupulous traders misuse antibiotics to treat some diseases such as mastitis in cows,leading to antibiotic residues in dairy products.Rapid,sensitive,and simple detection methods for antibiotic residues are particularly important for food safety in dairy products.Traditional detection technology can effectively detect antibiotics,but there are defects such as complicated pre-treatment and high cost.Biosensors are widely used in food safety due to fast detection speed,low detection cost,strong anti-interference ability,and suitability for the field application.Nevertheless,these sensors often fail to trigger the signal conversion output due to low target concentration.To cope with this issue,some high-efficiency signal amplification systems can be introduced to improve the detection sensitivity and linear range of biosensors.In this review,we focused on:(i)Sources and toxicity of major antibiotics in animal-derived foods.(ii)Nanomaterial-mediated biosensors for real-time detection of target antibiotics in animal-derived foods.(iii)Signal amplification techniques to increase the sensitivity of biosensors.Finally,future prospects and challenges in this research field are discussed.

Research of the relationship of intracellular acidification and apoptosis in Hela cells based on pH nanosensors

In this paper,the relationship of intracellular acidification and apoptosis in Hela cells induced by vin-cristine sulfate has been studied by use of the ratiometric pH nanosensors that have been developed by our group,employing fluorescein isothiocyanate(FITC) doped as the pH-sensitive dye and Tris(2,2'-bipyidyl) dichlororuthenium(II) hexahydrate(RuBpy) doped as reference dye. The pH change of the Hela cells induced by vincristine sulfate has been monitored in vivo,in situ and real time by use of the ratiometric pH nanosensors. The experimental results show that the pH of the apoptotic Hela cells induced by vincristine sulfate has been acidified from 7.11 to 6.51,and the percentage of intra-cellular acidification is correlated with the induced concentration and incubation time of the vincristine sulfate. The further study of the percentage of intracellular acidification and the percentage of apop-tosis of Hela cells at the same time reveals that apoptosis of Hela cells induced by vincristine sulfate is preceded by intracellular acidification. These results would provide theoretical foundation for the therapy of cancer through interfering the pH of cells by use of vincristine sulfate or other anti-cancer drugs.

Stable oligonucleotide-functionalized gold nanosensors for environmental biocontaminant monitoring

The global propagation of environmental biocontaminants such as antibiotic resistant pathogens and their antibiotic resistance genes（ARGs） is a public health concern that highlights the need for improved monitoring strategies. Here, we demonstrate the environmental stability and applicability of an oligonucleotide-functionalized gold nanosensor. The mec A ARG was targeted as model biocontaminant due to its presence in clinically-relevant pathogens and to its emergence as an environmental contaminant.mec A-specific nanosensors were tested for antibiotic resistance gene（ARG） detection in ARG-spiked effluent from four wastewater treatment plants（WWTPs）. The mec A-specific nanosensors showed stability in environmental conditions and in high ionic strength（[MgCl_2] 〈 50 m M）, and high selectivity against mismatched targets. Spectrophotometric detection was reproducible with an LOD of 70 pM（≈ 4 × 10~7 genes/μL）, even in the presence of interferences associated with non-target genomic DNA and complex WWTP effluent. This contribution supports the environmental applicability of a new line of cost-effective, field-deployable tools needed for wide-scale biocontaminant monitoring.

A highly sensitive ratiometric near-infrared nanosensor based on erbium-hyperdoped silicon quantum dots for iron(Ⅲ) detection

Ratiometric fluorescent detection of iron(Ⅲ)(Fe^(3+))offers inherent self-calibration and contactless analytic capabilities.However,realizing a dual-emission near-infrared(NIR)nanosensor with a low limit of detection(LOD)is rather challenging.In this work,we report the synthesis of water-dispersible erbium-hyperdoped silicon quantum dots(Si QDs:Er),which emit NIR light at the wavelengths of 810 and 1540 nm.A dual-emission NIR nanosensor based on water-dispersible Si QDs:Er enables ratiometric Fe^(3+)detection with a very low LOD(0.06μM).The effects of pH,recyclability,and the interplay between static and dynamic quenching mechanisms for Fe^(3+)detection have been systematically studied.In addition,we demonstrate that the nanosensor may be used to construct a sequential logic circuit with memory functions.

Review on the application of upconversion nanomaterials in heavy metal detection

As a widespread element,heavy metals have a significant impact on human health and threaten human health.It is of great significance to develop analytical technologies that can detect heavy metal ions quickly and accurately.In comparison to conventional fluorescent materials such as organic dyes,quantum dot(QD)labels,and carbon quantum dots(CD),fluorescence detection technology utilizing lanthanide(Ln)ion-doped upconversion nanoparticles(UCNPs)stands out due to its distinctive attributes.These include a notably reduced autofluorescence background,enhanced tissue penetration capabilities,biocompatibility with cellular tissues,and minimal photodamage inflicted on biological samples.The utilization of this technology has garnered considerable attention across multiple fields.In the domain of heavy metal detection,traditional laboratory methods necessitate costly instrumentation and a fully equipped laboratory,involving intricate sample processing procedures and protracted detection periods,as well as a demand for skilled personnel.In contrast,the implementation of this material offers rapid and cost-effective detection,significantly mitigating the technical barriers for operators.Consequently,this represents an exceptional avenue to curtail expenses and broaden the scope of detection within the analytical process.This paper reviews the research progress of UCNPs in the detection of heavy metal ions,encompassing a brief elucidation of the luminescence principle of upconversion nanomaterials and commonly used detection principles.Additionally,it provides a detailed overview of the research status of several common non-metal ions and essential heavy metals.Furthermore,it summarizes the current focal points in UCNP detection and discusses the challenges and prospects associated with it.

Thin films of α-Fe_(2)O_(3) nanoparticles using as nonmetallic SERS-active nanosensors for submicromolar detection

A new kind of nonmetallic nanosensors based on surface-enhanced Raman spectroscopy(SERS)have been successfully prepared by the assembly of α-Fe_(2)O_(3) nanoparticles(NPs)onto clean quartz surface via the cross-linker of hexamethylene diisocyanate(HDI).The resultant substrates have been characterized by electron micrographs,which show that the α-Fe_(2)O_(3) NPs distribute on the modified surface uniformly with a monolayer or sub-monolayer structure.4-mercaptopyridine(4-Mpy)and 2-mercaptobenzothiazole(2-MBT)molecules have been used as SERS probes to estimate the detection efficiency of the α-Fe_(2)O_(3) thin films.The SERS experiments show that it is possible to record high quality SERS spectra from probe molecules on the α-Fe_(2)O_(3) thin films at sub-micromolar(<10^(–6) mol/L)concentration.These results indicate that the highly ordered,uniformly roughed,highly sensitive and low-cost α-Fe_(2)O_(3) thin films are excellent candidates for nonmetallic SERS-active nanosensors.

Silicene nanoribbons as carbon monoxide nanosensors with molecular resolution

Applications based on silicene as grown on substrates are of high interest toward actual utilization of this unique material. Here we explore, from first principles, the nature of carbon monoxide adsorption on semiconducting silicene nanoribbons and the resulting quantum conduction modulation with and without silver contacts for sensing applications. We find that quantum conduction is detectably modified by weak chemisorption of a single CO molecule on a pristine silicene nanoribbon. This modification can be attributed to the charge transfer from CO to the silicene nanoribbon and the deformation induced by the CO chemisorption. Moderate binding energies provide an optimal mix of high detectability and recoverability. With Ag contacts attached to a -1 nm silicene nanoribbon, the interface states mask the conductance modulations caused by CO adsorption, emphasizing length effects for sensor applications. The effects of atmospheric gases--nitrogen, oxygen, carbon dioxide, and water--as well as CO adsorption density and edge-dangling bond defects, on sensor functionality are also investigated. Our results reveal pristine silicene nanoribbons as a promising new sensing material with single molecule resolution.

Surface-enhanced Raman scattering nanosensors for in vivo detection of nucleic acid targets in a large animal model

Although nanotechnology has led to important advances in in vitro diagnostics, the development of nanosensors for in vivo detection remains very challenging. Here, we demonstrated the proof-of-principle of in vivo detection of nudeic acid targets using a promising type of surface-enhanced Raman scattering （SERS） nanosensor implanted in the skin of a large animal model （pig）. The in vivo nanosensor used in this study involves the ＂inverse molecular sentinel＂ detection scheme using plasmonics-active nanostars, which have tunable absorption bands in the near infrared region of the ＂tissue optical window＂, rendering them efficient as an optical sensing platform for in vivo optical detection. Ex vivo measurements were also performed using human skin grafts to demonstrate the detection of SERS nanosensors through tissue. In this stud, a new core--shell nanorattle probe with Raman reporters trapped between the core and shell was utilized as an internal standard system for self-calibration. These results illustrate the usefulness and translational potential of the SERS nanosensor for in vivo biosensing.

Exploring ratiometric endolysosomal pH nanosensors with hydrophobic indicators responding at the nanoscale interface and multiple fluorescence resonance energy transfers

Compared with conventional water-soluble fluorescence probes,pH-sensitive fluorescent nanosensors based on hydrophobic indicators remain largely unexplored.We report here the unique pH response of the nanosensors with a hydrophobic indicator(Ch3,a Nile Blue derivative)in polymeric nanoparticles(NPs).At the aqueous-organic interface of the NPs,spectral overlap and dye accumulation caused significant Förster resonance energy transfer(FRET)not only between the protonated and deprotonated Ch3(hetero-FRET),but also between the protonated and deprotonated Ch3 themselves(homo-FRET).The pH response was simulated according to an interfacial response mechanism and the dynamic range was found to depend on the size of the NPs and dye distribution(Kp).Therefore,adjusting the size of the NPs and the local dye concentration gave rise to a series of dynamic sensing ranges with apparent pKa values from 2.7 to 9.6 based on a single indicator.The nanosensors were successfully delivered to HeLa cells to monitor subcellular pH values in the endosomes and lysosomes.Based on cellular calibrations,the average pH in the organelles were determined to be ca.4.7.Moreover,the pH neutralization process during lysosome membrane permeabilization(LMP)induced by hydrogen peroxide stimulation was also successfully visualized with the nanosensors.

Recent advances in nano-enabled agriculture for improving plant performance

Nano-enabled agriculture is an emerging hot topic.To facilitate the development of nano-enabled agriculture,reviews addressing or discussing the applications,knowledge gap,future research needs,and possible new research field of plant nanobiotechnology in agricultural production are encouraged.Here we review the following topics in plant nanobiotechnology for agriculture:1)improving stress tolerance,2)stress sensing and early detection,3)targeted delivery and controlled release of agrochemicals,4)transgenic events in non-model crop species,and 5)seed nanopriming.We discuss the knowledge gaps in these topics.Besides the use of nanomaterials for harvesting more electrons to improve photosynthetic performance,they could be used to convert n IR and UV to visible light to expand the light spectrum for photosynthesis.We discuss this approach to maintaining plant photosynthesis under light-insufficient conditions.Our aim in this review is to aid researchers to learn quickly how to use plant nanobiotechnology for improving agricultural production.

Analysis and Trends for Future MEMS Markets

Micro and Nano technology are engineering on an extremely small scale. Already they are being applied to create many new products. Nanotechnology is predicted to become the basis for remarkably powerful and inexpensive computers, fundamentally new medical technologies that could save millions of lives, sensors important in military application as well as environmental protection. The main aim of this review is to concentrate information from different printed and online sources and help to make a right decision in very dynamic sensor market as well as let know what we should expect in the nearest future.

Peptide Functionalized Nanoplasmonic Sensor for Explosive Detection

In this study, a nanobiosensor for detecting explosives was developed, in which the peptide was synthesized with trinitrotoluene(TNT)-specific sequence and immobilized on nanodevice by Au–S covalent linkage, and the nanocup arrays were fabricated by nanoimprint and deposited with Au nanoparticles to generate localized surface plasmon resonance(LSPR). The device was used to monitor slight change from specific binding of 2,4,6-TNT to the peptide. With high refractive index sensing of ~10~4nm/RIU, the nanocup device can detect the binding of TNT at concentration as low as3.12×10^(-7)mg mL^(-1) by optical transmission spectrum modulated by LSPR. The nanosensor is also able to distinguish TNT from analogs of 2,4-dinitrotoluene and 3-nitrotoluene in the mixture with great selectivity. The peptide-based nanosensor provides novel approaches to design versatile biosensor assays by LSPR for chemical molecules.

Remote Tracking Gas Molecular via the Standalone-Like Nanosensor-Based Tele-Monitoring System

Remote tracking the variation of air quality in an effective way will be highly helpful to decrease the health risk of human short-and long-term exposures to air pollution.However,high power consumption and poor sensing performance remain the concerned issues,thereby limiting the scale-up in deploying air quality tracking networks.Herein,we report a standalone-like smart device that can remotely track the variation of air pollutants in a power-saving way.Brevity,the created smart device demonstrated satisfactory selectivity(against six kinds of representative exhaust gases or air pollutants),desirable response magnitude(164–100 ppm),and acceptable response/recovery rate(52.0/50.5 s),as well as linear response relationship to NO2.After aging for 2 weeks,the created device exhibited relatively stable sensing performance more than 3 months.Moreover,a photoluminescence-enhanced light fidelity(Li-Fi)telecommunication technique is proposed and the Li-Fi communication distance is significantly extended.Conclusively,our reported standalone-like smart device would sever as a powerful sensing platform to construct high-performance and low-power consumption air quality wireless sensor networks and to prevent air pollutant-induced diseases via a more effective and low-cost approach.

Protein-mimicking nanoparticle(Protmin)-based nanosensor for intracellular analysis of metal ions

In this study, we designed and applied proteinmimicking nanoparticles(Protmin) as an intracellular nanosensor for in vivo detection of lead ions(Pb^(2+)).Monodispersed gold nanoparticles(Au NPs) of 13 nm in diameter were modified using poly-adenine-tailed Pb^(2+)-specific 8–17 DNAzyme to form a spherical and functional Protmin. Substrate strands modified with a fluorophore at the 50 end and a quencher at the 30 end were bound to DNAzyme. Pb^(2+) facilitated cleavage of DNAzyme to release the fluorophore-modified short strands to generate fluorescence. We observed rapid kinetics of the Protmin nanosensor, for which the typical assay time was 10 min.Further, we demonstrated the Protmin nanosensor could readily enter living cells and respond to Pb^(2+) in the intracellular environment. The broad of range of Protmindesigns will be useful for advancing biological and medical applications.

Enhancing UV photosensitivity of a ZnO UV nanosensor using electrical stimulation at megahertz frequency

We report a novel technique to enhance the ultraviolet （UV） photosensitivity of a ZnO nanosensor with ZnO nanowires bridged on micromachined metallic electrodes. The experimental results reveal that the photoconductivity and the time response of the ZnO nanowire sensor with either Schottky or Ohmic contacts are significantly improved by electrifying the nanowire sensors using an alternating current at the frequency of megahertz. An integrated UV sensor incorporating ZnO nanowires with a constant current mode driving circuit is developed, which demonstrates promising sensitivity and time response to UV illumination with a low power consumption.

Novel Formaldehyde Sensor based on Hydrogen Peroxide/Melamine Modulated Photoluminescence of Nitrogen-doped Graphene Quantum Dots

A modulated photoluminescence nanosensor was developed for the quantitative detection of formaldehyde with nitrogen-doped graphene quantum dots and melamine. The sensing system was based on the different activated effects of melamine and hydrogen peroxide on the photoluminescence intensity of nitrogendoped graphene quantum dots. Under the optimal conditions, the modulated photoluminescence sensing system can be used to detect formaldehyde with a good linear relationship between the nitrogen-doped graphene quantum dots photoluminescence difference and the concentration of formaldehyde. The novel sensing system provided new directions for the detection of formaldehyde with high selectivity and quick response.

New Silver Nanosensor for Nickel Traces. Part II： Urinary Nickel Determination Associated to Smoking Addiction

A new fluorescence silver nanosensor assisted by surfactant has been recently synthesized and applied to ultra trace nickel determination. The methodology was validated by the standard addition method and satisfactorily applied to nickel determination in urine without previous treatment, coming from subjects with different smoking addiction levels and second hand smokers. Within-day precision was better than 0.011 CV. The reproducibility （between-days precision） was also evaluated over 3 days by performing six determinations each day with a CV of 0.025. The proposed methodology represents a promising approach in the area of biological monitoring due to its low operation cost, simplicity of instrumentation, high sampling speed and non-polluting solvents. Obtained results of urinary nickel concentration were successfully correlated with the tobacco addiction.

New Silver Nanosensor for Nickel Traces： Synthesis, Characterization and Analytical Parameters

A new fluorescence silver nanosensor assisted by surfactant has been synthesized and applied to ultra trace nickel determination. Operational variables which influence nanomaterial synthesis have been studied and optimized. Synthesis was very fast and simple using non polluting solvents; silver chemical reduction was carried out at room temperature. Spectroscopic studies were carried out in order to assure the uniformed of nanomaterial obtained. Fluorescent signal of silver nanoparticles resulted enhanced in presence of Ni（II）. At optimal experimental conditions, a detection limit of 0.036 pg＇L1 and quantification limit 0.12 pg＇L~ were obtained. The calibration sensitivity was 2 x 1014 L.pg-l.cm1 for the new methodology, with a range of linearity of six orders of magnitude between 0.12 and 2.93 × 10^5 pg L^-1. The tolerance levels for potential interferent ions were studied with good results. The proposed methodology represents a promising approach for Ni（II） traces quantification due to its low operation cost, simplicity of instrumentation, high sampling speed and non-polluting solvents.

Design of Environmental Biosensor Based on Photonic Crystal Fiber with Bends Using Finite Element Method

In this paper, a biosensor based on photonic crystal fiber (PCF) is proposed and designed using Full-Vectorial Finite Element Method (FVFEM). The proposed PCF sensor consists of three concentric circles surrounding the core. The key optical sensor characteristics such as sensitivity, the field profiles and real part of the refractive index of the proposed PCF structure are investigated by employing the FVFEM. The proposed sensor can be deployed for environmental sensing when the PCF active region is filled with either analytes such as liquids or gas. By careful selection of the design parameters such as the radius of the sensing circle, the diameter of air holes in the core region and hole to hole spacing, Λ, the sensitivity analytes is determined. Our simulation results show that, the electric field distribution is primary localized in the third concentric circle with a radius of 16 μm. Effects of PCF bending on the sensitivity is also studied and reported.