Carbon nanotubes exhibit many unique intrinsic physical and chemical properties and have been intensively explored for biological and biomedical applications in the past few years. In this ...comprehensive review, we summarize the main results from our and other groups in this field and clarify that surface functionalization is critical to the behavior of carbon nanotubes in biological systems. Ultrasensitive detection of biological species with carbon nanotubes can be realized after surface passivation to inhibit the non-specific binding of biomolecules on the hydrophobic nanotube surface. Electrical nanosensors based on nanotubes provide a label-free approach to biological detection. Surface-enhanced Raman spectroscopy of carbon nanotubes opens up a method of protein microarray with detection sensitivity down to 1 fmol/L.
In vitro
and
in vivo
toxicity studies reveal that highly water soluble and serum stable nanotubes are biocompatible, nontoxic, and potentially useful for biomedical applications.
In vivo
biodistributions vary with the functionalization and possibly also size of nanotubes, with a tendency to accumulate in the reticuloendothelial system (RES), including the liver and spleen, after intravenous administration. If well functionalized, nanotubes may be excreted mainly through the biliary pathway in feces. Carbon nanotube-based drug delivery has shown promise in various
In vitro
and
in vivo
experiments including delivery of small interfering RNA (siRNA), paclitaxel and doxorubicin. Moreover, single-walled carbon nanotubes with various interesting intrinsic optical properties have been used as novel photoluminescence, Raman, and photoacoustic contrast agents for imaging of cells and animals. Further multidisciplinary explorations in this field may bring new opportunities in the realm of biomedicine.
In this study, the Coriolis effects on the vibration behavior of the multilayer rotating piezoelectric nanobeam are investigated. The governing equations are obtained using the nonlocal continuum and ...surface elasticity theories. The axial and transverse governing equations are influenced by the Coriolis effects. The differential quadrature method (DQM) is applied to obtain the vibration frequencies of the multilayer piezoelectric nanobeams. A good correlation is obtained between the numerical results and the results presented in available literature. The influences of the different boundary conditions and the thermal change in the vibration behavior of multilayer piezoelectric nanobeams are studied. The present work shows that the Coriolis effects strongly affect the vibration behavior of multilayer piezoelectric nanobeams. The numerical results show that the Coriolis effects under the flexible boundary conditions are more significant than rigid boundary conditions. The results of this study can be used to design and manufacture nanosensors, biosensors, atomic force microscopes, nanoelectromechanical systems, and micro-electromechanical systems (NEMS/MEMS) devices.
For the early diagnosis and effective evaluation of treatment effects of inflammation, a de novo bioanalytical method is urgently needed to monitor the metabolite nitric oxide (NO) associated with ...inflammatory diseases. However, developing a reliable detection method with excellent water solubility, biocompatibility, long retention time, and blood circulation is still challenging. In this work, we reported for the first time a de novo host–guest self-assembled nanosensor CTA for the quantitative detection and visualization of NO levels in inflammatory models. CTA mainly consists of two parts: (i) an adamantyl-labeled guest small-molecule RN-adH containing a classical response moiety o-phenylenediamine for a chemical-specific response toward NO and fluorophore rhodamine B with excellent optical properties as an internal reference for self-calibration and (ii) a remarkable water-soluble and biocompatible supramolecular β-cyclodextrin polymer (Poly-β-CD) host. In the presence of NO, the o-phenylenediamine unit was reacted with NO at a low pH value of ∼7.0, accompanied by changes in the intensity of the two emission peaks corrected for each other and the change in fluorescence color of the CTA solution from fuchsia to pink. Furthermore, CTA was an effective tool for NO detection with a fast response time (∼60 s), high selectivity, and sensitivity (LOD: 22.3 nM). Impressively, the CTA nanosensor has successfully achieved the targeted imaging of NO in living inflammatory RAW 264.7 cells and mice models with satisfactory results, which can provide a powerful molecular tool for the visualization and assessment of the occurrence and development of NO-related inflammatory diseases in complex biosystems.
We present a pH nanosensor conceived for single intracellular measurements. The sensing architecture consisted of a two-electrode system evaluated in the potentiometric mode. We used solid-contact ...carbon nanopipette electrodes tailored to produce both the indicator (pH nanosensor) and reference electrodes. The indicator electrode was a membrane-based ion-selective electrode containing a receptor for hydrogen ions that provided a favorable selectivity for intracellular measurements. The analytical features of the pH nanosensor revealed a Nernstian response (slope of −59.5 mV/pH unit) with appropriate repeatability and reproducibility (variation coefficients of <2% for the calibration parameters), a fast response time (<5 s), adequate medium-term drift (0.7 mV h–1), and a linear range of response including physiological and abnormal cell pH levels (6.0–8.5). In addition, the position and configuration of the reference electrode were investigated in cell-based experiments to provide unbiased pH measurements, in which both the indicator and reference electrodes were located inside the same cell, each of them inside two neighboring cells, or the indicator electrode inside the cell and the reference electrode outside of (but nearby) the studied cell. Finally, the pH nanosensor was applied to two cases: (i) the tracing of the pH gradient from extra-to intracellular media over insertion into a single PC12 cell and (ii) the monitoring of variations in intracellular pH in response to exogenous administration of pharmaceuticals. It is anticipated that the developed pH nanosensor, which is a label-free analytical tool, has high potential to aid in the investigation of pathological states that manifest in cell pH misregulation, with no restriction in the type of targeted cells.
O6-Methylguanine-DNA-methyltransferase (MGMT) is a demethylation protein that dynamically regulates the O6-methylguanine modification (O6 MeG), and dysregulated MGMT is implicated in various ...malignant tumors. Herein, we integrate demethylation-activated DNAzyme with a single quantum dot nanosensor to sensitively detect MGMT in breast tissues. The presence of MGMT induces the demethylation of the O6 MeG-caged DNAzyme and the restoration of catalytic activity. The activated DNAzyme then specifically cleaves the ribonucleic acid site of hairpin DNA to expose toehold sequences. The liberated toehold sequence may act as a primer to trigger a cyclic exponential amplification reaction for the generation of enormous signal strands that bind with the Cy5/biotin-labeled probes to form sandwich hybrids. The assembly of sandwich hybrids onto 605QD obtains 605QD-dsDNA-Cy5 nanostructures, inducing efficient FRET between the 605QD donor and Cy5 acceptor. Notably, the introduction of a mismatched base in hairpin DNA can greatly minimize the background and improve the signal-to-noise ratio. This nanosensor achieves a dynamic range of 1.0 × 10–8 to 0.1 ng/μL and a detection limit of 155.78 aM, and it can screen MGMT inhibitors and monitor cellular MGMT activity with single-cell sensitivity. Moreover, it can distinguish the MGMT level in tissues of breast cancer patients and healthy persons, holding great potential in clinical diagnostics and epigenetic research studies.
Abstract
The growth in human population is estimated to reach 9.8 billion by mid-2050. To meet the food requirements, reducing the judicious use of fertilizers, agrochemicals and their impact on ...environment, soil, water, humans and the surrounding biodiversity we have to shift towards sustainable methods. Nanotechnology is one such technology that will help in crop production by improving the input use efficiency by minimizing their losses, site-specific, controlled delivery of fertilizers or agrochemical as per the requirement, increases shelf life, efficiency of the agrochemicals and reduces their recommended dosage. Nanoparticles are organic, inorganic or hybrid materials whose dimensions may range from 1 to 100 nm. Nanosensors can detect environmental stress and enhance the plant’s ability to combat diseases, used in automation of irrigation; it is a rapid and accurate tool to detect insect and pest, which helps in timely application of agrochemicals. Nano-iron fertilizer was found to improve essential oil content, nano-zinc and boron fertilizers improved fruit yield and quality, nano zeolite can sustain the nutrients in the soil for long term and it enhance germination and plant growth. As nanoparticles enhances growth, they aid in early maturity of the crop, improves the plant’s ability to tolerate stresses, hence they are effective tools in drought and flood-prone areas, they detoxify harmful pollutants especially heavy metals, pesticide residues. As nanoparticles have greater persistence, they may have long-term effect on plants, humans and also environment, but it has less impact than that of the normal agrochemicals. Advanced research is required to conclude in this aspect.
Here, a molecular imprinting technique was employed to create an SPR-based nanosensor for the selective and sensitive detection of organophosphate-based coumaphos, a toxic insecticide/veterinary drug ...often used. To achieve this, UV polymerization was used to create polymeric nanofilms using
-methacryloyl-l-cysteine methyl ester, ethylene glycol dimethacrylate, and 2-hydroxyethyl methacrylate, which are functional monomers, cross-linkers, and hydrophilicity enabling agents, respectively. Several methods, including scanning electron microscopy (SEM), atomic force microscopy (AFM), and contact angle (CA) analyses, were used to characterize the nanofilms. Using coumaphos-imprinted SPR (CIP-SPR) and non-imprinted SPR (NIP-SPR) nanosensor chips, the kinetic evaluations of coumaphos sensing were investigated. The created CIP-SPR nanosensor demonstrated high selectivity to the coumaphos molecule compared to similar competitor molecules, including diazinon, pirimiphos-methyl, pyridaphenthion, phosalone,
-2,4(dimethylphenyl) formamide, 2,4-dimethylaniline, dimethoate, and phosmet. Additionally, there is a magnificent linear relationship for the concentration range of 0.1-250 ppb, with a low limit of detection (LOD) and limit of quantification (LOQ) of 0.001 and 0.003 ppb, respectively, and a high imprinting factor (I.F.4.4) for coumaphos. The Langmuir adsorption model is the best appropriate thermodynamic approach for the nanosensor. Intraday trials were performed three times with five repetitions to statistically evaluate the CIP-SPR nanosensor's reusability. Reusability investigations for the two weeks of interday analyses also indicated the three-dimensional stability of the CIP-SPR nanosensor. The remarkable reusability and reproducibility of the procedure are indicated by an RSD% result of less than 1.5. Therefore, it has been determined that the generated CIP-SPR nanosensors are highly selective, rapidly responsive, simple to use, reusable, and sensitive for coumaphos detection in an aqueous solution. An amino acid, which was used to detect coumaphos, included a CIP-SPR nanosensor manufactured without complicated coupling methods and labelling processes. Liquid chromatography with tandem mass spectrometry (LC/MS-MS) studies was performed for the validation studies of the SPR.
Fluorescent DNA nanosensors have been widely used due to their unique advantages, among which the near-infrared (NIR) imaging mode can provide deeper penetration depth and lower biological background ...for the nanosensors. However, efficient NIR quenchers require ingenious design, complex synthesis, and modification, which severely limit the development of NIR DNA nanosensors. Label-free strategies based on G-quadruplex (G4) and NIR G4 dyes were first introduced into in situ extracellular imaging, and a novel NIR sensing strategy for the specific detection of extracellular targets is proposed. The strategy avoids complex synthesis and site-specific modification by controlling the change of the NIR signal through the formation of a G4 nanostructure. A light-up NIR DNA nanosensor based on potassium ion (K+)-sensitive G4 chain PS2.M was constructed to verify the strategy. PS2.M forms a stable G4 nanostructure in the presence of K+ and activates the NIR G4 dye CSTS, thus outputting NIR signals. The nanosensor can rapidly respond to K+ with a linear range of 5–50 mM and has good resistance to interference. The nanosensor with cholesterol can provide feedback on the changes in extracellular K+ concentration in many kinds of cells, serving as a potential tool for the study of diseases such as epilepsy and cancer, as well as the development of related drugs. The strategy can be potentially applied to the NIR detection of a variety of extracellular targets with the help of functional DNAs such as aptamer and DNAzyme.
Fluorescent nanodiamonds are gaining increasing attention as fluorescent labels in biology in view of the fact that they are essentially nontoxic, do not bleach, and can be used as nanoscale sensors ...for various physical and chemical properties. To fully realize the nanosensing potential of nanodiamonds in biological applications, two problems need to be addressed: their limited colloidal stability, especially in the presence of salts, and their limited ability to be taken up by cells. We show that the physical adsorption of a suitably designed recombinant polypeptide can address both the colloidal stability problem and the problem of the limited uptake of nanodiamonds by cells in a very straightforward way, while preserving both their spectroscopic properties and their excellent biocompatibility.
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