Nano Research & Applications

Description

Neuromodulation has been linked to the pathogenesis of numerous neurological and psychiatric disorders because of its dysregulation, which is critical to the regulation of brain function. However, optical tools have only become available in recent years to investigate the spatial and temporal profiles of neuromodulator signaling, including dopamine, with the necessary resolution to discover neuromodulation mechanisms. The state of synthetic nanomaterial-based optical nanosensors for high-resolution monitoring of neurotransmission is summarized in this review. In particular, we discuss how synthetic nanosensors can reveal the temporal dynamics and spatial diffusion of neuromodulator release as well as the spatial distribution of release sites in space. Next, we talk about the benefits and drawbacks of the nanosensors that are currently on the market, as well as their recent use for imaging dopamine release from within brain tissue. Lastly, we talk about ways to improve nanosensors for use in vivo, which could have an impact on translational applications. As the most prevalent intracellular reductive substances, Ascorbic Acid (AA) and glutathione (GSH) have been extensively utilized as biomarkers for the identification of cancer cells. Since AA and GSH share a mutual conversion relationship, the current methods for identifying cancer cells that rely solely on imaging of AA or GSH may result in systematic errors. A fluorescent nanosensor for simultaneously imaging intracellular reductive substances like AA and GSH is the idea presented here. It was made fluorescent, biocompatible silicon nanoparticles (SiNPs) with a lot of amine and carboxyl groups on the surface.

Nanosensor Based On Upconversion Nanoparticles

Chelation of Fe3+ ions initially stifled the SiNP's fluorescence, resulting in the fluorescent nanosensor's SiNP/Fe3+ complex. The nanosensor recovered with sensitivity and fluorescence during the redox reaction with reducing substances. In addition, by simultaneously imaging intracellular AA and GSH, the fluorescent nanosensor was able to precisely distinguish human breast carcinoma (MCF-7) cells from normal mammary epithelial (MCF-10A) cells thanks to the efficient cellular uptake of SiNP/Fe3+ and the overexpression of intracellular reductive substances in cancer cells. When it comes to imaging-guided precision cancer diagnosis, this strategy could be very useful. In clinics, heparin is an important anticoagulant that must be regularly detected and dose adjusted. While most fluorescent sensors suffer from spontaneous fluorescence for excitation under short-wavelength light, the occurrence of false positives, complex and time-consuming preparation, and expensive detection instruments, fluorimetry is a powerful tool because of its fast response and high sensitivity. For the purpose of colorimetric and fluorescent heparin detection, we developed a nanosensor based on upconversion nanoparticles in this section. The low Limit of Detection (LOD) for heparin detected by the nanosensor was 0.1 nM in fluorescent mode and 0.3 nM in colorimetric mode, respectively. We also used a smartphone-sensing platform to quantitatively detect heparin with a LOD of 2 nM. The designed nanosensor could effectively eliminate auto-fluorescence based on long-wavelength excitation and fluorescent-colorimetric dual-response detection signal, thereby expanding applications for bedside heparin assay and related medical safety. PANI (polyaniline) and PDMS (polydimethylsiloxane) have created a creatinine nanosensor.

The Tribo-Electric Nanogenerator (TENG)-creatinine enzymatic reaction coupling is cited as the mechanism. Due to a shift in the electroconductivity of PANI during the enzymatic reactions, the triboelectric outputs of PANI and PDMS carry information about the ambient creatinine concentration after enzymatic modification. At room temperature, the nanosensors demonstrate high sensitivity. When creatinine concentration is 103 mol/L, the response reaches 51.42 percent, and its selectivity for creatinine is superior to that of NaCl, glucose, and urea. Additionally, the nanosensor allows for a wide range of bending angle measurements (10°–40°), which raises the possibility of creatinine detection in wearable sensing applications. The flexible nanosensor can detect creatinine continuously and without any invasive procedures, paving the way for electronic skin and self-powered healthcare systems. It is still difficult to selectively sense these metal ions and image them in vivo due to their similar charges, atomic radii, and chemical properties. To image and detect Pb2+, a DNAzyme-assembled and light-excited near-infrared (NIR) nanosensor was developed.NaYF4: In this nanosensor: The donor of the luminescence resonance energy transfer (LRET) was Yb, Er upconversion nanoparticles (UCNPs), which were used as a NIR-to-Vis transducer. The acceptor of the energy transfer was DNAzyme-functionalized black hole quencher 1 (BHQ1). Pb2+ was detected in solution using this proposed nanosensor with high selectivity and sensitivity. In addition, we have successfully demonstrated that this nanosensor can image Pb2+ in living cells and early-stage zebrafish with good photostability and negligible autofluorescence. The UCNP-DNAzyme nanosensor would improve the imaging of Pb2+ in vivo and could be used to learn more about Pb2+'s metabolic pathways and lead poisoning's underlying mechanism. Alpha-Fetoprotein (AFP) and Golgi protein 73 (GP73) are biomarkers for Hepatocellular Carcinoma (HCC). A sensitive and specific multiplex immunoassay has been developed for these biomarkers. After being modified with active reactive groups from click chemistry, the enzymes Alkaline Phosphatase (ALP) and Horse Radish Peroxidase (HRP) self-assembled into the aggregates known as HRPn and ALPn, respectively.

Hydrothermally Synthesized Carbon Dots

The immuno nanosensor for AFP and GP73 was created by conjugating the Carbon Nanotubes (CNT) in a bioorthogonal reaction with biomarker detection antibody and enzyme aggregates. Chemiluminescences can be read out in a variety of time windows thanks to the nanosensor's enzymes' ability to catalyze their substrate's emission. The bioorthogonal reaction's high efficiency allowed for the conjugation of large amounts of catalytic enzymes to the surface of CNT, significantly increasing the signal intensity of chemiluminescence. The multiplex immunoassay has been used to find biomarkers in real serum samples, which can make the clinical diagnosis of HCC more accurate and precise. The biomarkers of HCC are highly specific for the nanosensors, and their sensitivities can be adjusted to meet actual demand. A novel clue to the development of an immunoassay for clinical HCC diagnosis is provided by this work. The creation of optical nanosensors based on hydrothermally synthesized Carbon Dots (CD) for measuring the pH and temperature of liquid media is the focus of this research. With an accuracy of 0.005 pH units and 0.67 °C, artificial neural networks were applied to the CD fluorescence spectra database to simultaneously determine pH and ambient temperature values. The results that were obtained are one of a kind because they show that it is possible to make a multifunctional CD-based nanosensor that works over a wide temperature range (22–81°C) and can measure pH with an accuracy that is higher than that of nanoscale analogs by an order of magnitude. While the "always on" mode frequently hinders its clinical applications, integration of disease diagnosis and treatment is essential for precise medicine. An integrated dual-mode glucose nanosensor as an activable theranostic platform is developed here, inspired by cascaded catalysis. This platform is further utilized for cancer cell recognition and enhanced synergistic therapy of lymph cancer. The in-situ growth of silver nanoparticles (AgNPs) is combined with the synergistic reduction of Tannic Acid (TA) and Graphene Quantum Dots (GQDs), which are further embellished with Glucose Oxidase (GOx), to create this nanosensor. When glucose initiates a cascaded catalytic reaction, GOx oxidizes glucose into gluconic acid and hydrogen peroxide (H2O2), and GQDs nanozyme with peroxidase-like activity catalyzes the production of hydroxyl radical (•OH), resulting in the degradation and the release of Ag+. As a result, a dual-mode glucose nanosensor with a "turn-off" colorimetric and "turn-on" fluorescence mode is constructed. This type of glucose nanosensor can quickly be used to identify cancer cells through fluorescence imaging based on the high glucose level in the tumor microenvironment. In addition, the cascades-enhanced synergistic treatment of lymphoma using a combination of starving-like therapy, metal ion therapy, and TA-induce apoptosis is made easier by the degradation of glucose. A glucose-activated theranostic nanoplatform is the focus of this study, which presents a significant opportunity for biosensing, bioimaging, and biomedical applications related to cancer.