Dopamine functionalized CuO nanoparticles: A high valued “turn on” colorimetric biosensor for detecting cysteine in human serum and urine samples

Nitrodopamine modified MnO2 NS-MoS2QDs hybrid nanocomposite for the extracellular and intracellular detection of glutathione

We have developed a highly sensitive and reliable fluorescence resonance energy transfer (FRET) probe using nitro-dopamine (ND) and dopamine (DA) coated MnO2 nanosheet (ND@MnO2 NS and DA@MnO2 NS) as an energy acceptor and MoS2 quantum dots (QDs) as an energy donor. By employing surface-modified MnO2 NS, we can effectively reduce the fluorescence intensity of MoS2 QDs through FRET. It can reduce MnO2 NS to Mn2+ and facilitate the fluorescence recovery of the MoS2 QDs. This ND@MnO2 NS@MoS2 QD-based nanoprobe demonstrates excellent sensitivity to GSH, achieving an LOD of 22.7 nM in an aqueous medium while exhibiting minimal cytotoxicity and good biocompatibility. Moreover, our sensing platform shows high selectivity to GSH towards various common biomolecules and electrolytes. Confocal fluorescence imaging revealed that the nanoprobe can image GSH in A549 cells. Interestingly, the ND@MnO2 NS nanoprobe demonstrates no cytotoxicity in living cancer cells, even at concentrations up to 100 μg mL-1. Moreover, the easy fabrication and eco-friendliness of ND@MnO2 NS make it a rapid and simple method for detecting GSH. We envision the developed nanoprobe as an incredible platform for real-time monitoring of GSH levels in both extracellular and intracellular mediums, proving valuable for biomedical research and clinical diagnostics.

A dual-channel sensor array for discrimination of biothiols based on manganese dioxide nanosheets

A dual-signal sensor array for highly sensitive identification of biothiols is reported based on different optical responses of MnO₂/curcumin (CUR) system to different biothiols. The addition of MnO₂ nanosheets (MnO₂ NSs) quenches the fluorescence of CUR, and the color of the mixture changes from yellow to brown. In the presence of reductive biothiols, MnO₂ NSs are etched and lose their fluorescence quenching ability, resulting in an increase in the fluorescence intensity of CUR at 540 nm and a decrease in the absorbance at 430 nm. The sensor array generates specific response modes based on the varying reduction abilities of different biothiols, which can be distinguished by linear discriminant analysis (LDA). The sensor array successfully distinguished five biothiols (glutathione (GSH), dithiothreitol (DTT), cysteine (Cys), mercaptoethanol (ME), and homocysteine (Hcy)) across a wide concentration range (1 μM-100 μM) and biothiol mixtures with varing molar ratios.

Recent innovations in the technology and applications of low-dimensional CuO nanostructures for sensing, energy and catalysis

Low-dimensional copper oxide nanostructures are very promising building blocks for various functional materials targeting high-demanded applications, including energy harvesting and transformation systems, sensing and catalysis. Featuring a very high surface-to-volume ratio and high chemical reactivity, these materials have attracted wide interest from researchers. Currently, extensive research on the fabrication and applications of copper oxide nanostructures ensures the fast progression of this technology. In this article we briefly outline some of the most recent, mostly within the past two years, innovations in well-established fabrication technologies, including oxygen plasma-based methods, self-assembly and electric-field assisted growth, electrospinning and thermal oxidation approaches. Recent progress in several key types of leading-edge applications of CuO nanostructures, mostly for energy, sensing and catalysis, is also reviewed. Besides, we briefly outline and stress novel insights into the effect of various process parameters on the growth of low-dimensional copper oxide nanostructures, such as the heating rate, oxygen flow, and roughness of the substrates. These insights play a key role in establishing links between the structure, properties and performance of the nanomaterials, as well as finding the cost-and-benefit balance for techniques that are capable of fabricating low-dimensional CuO with the desired properties and facilitating their integration into more intricate material architectures and devices without the loss of original properties and function.

Flexible-fabricated sensor module with programmable magnetic actuators coupled to L-cysteine functionalized Ag@Fe3O4 complexes for Cu2+ detection in fish tissues

Heavy metal contamination for seafood, particularly fish, is arising great concerns, and consequentially it is necessary to develop a simple and direct detection method. In this work, Ag@Fe₃O₄ is successfully prepared by simple solvothermal method, and we present a flexible-fabricated sensor module with assembled programmable magnetic actuators. The resulting sensor integrates a three-electrode system with two programmable magnetic actuators at the bottom of the device, which regulates the amount of current by adjusting the brake to control the adsorption force and vibration. The L-Cysteine functionalized Ag@Fe₃O₄ is coated on the surface of the electrode, then the Cu²⁺ is dropped into the reaction tank. Its performance is studied by cyclic voltammetry and electrochemical impedance spectroscopy, and the key experimental conditions such as deposition potential, deposition time, and electrolyte pH are gradually optimized. Under optimal conditions, Cu²⁺ can be detected over a wide linear range (0.01 ~ 4 μM) and at a low LOD (0.34 nM). The results show that the proposed method has a good application prospect in the detection of Cu²⁺. This method is successfully applied to Cu²⁺ analysis in fish samples with an acceptable recovery of 93 ~ 102%.

Polydopamine-assisted tranilast immobilization on a PLA chamber to enhance fat flaps regeneration by reducing tissue fibrosis

Tissue engineering chambers (TECs) have been shown to be useful in regenerating adipose tissue. However, tissue fibrosis caused by the chambers compromises the final volume of the newly formed adipose tissue. Surface modifications can compensate for the lack of biocompatibility of an implant. Tranilast (Tra) is an antifibrotic drug used to treat fibrotic pathologies, including keloids and scleroderma. In this study, a polydopamine-assisted tranilast coating (pDA + Tra) was prepared on a polylactic acid (PLA) chamber to minimize tissue fibrosis and achieve a large volume of fat flap regeneration. The in vitro results showed that, in contrast to a PLA chamber, roughness increased, and the fibroblast adhesion and smooth muscle antibody-positive immunoreactivity decreased in the PLA + pDA + Tra chamber. In addition, pedicled adipose tissue flaps were separated from the back of the rabbit and inserted into each chamber using the classic TEC procedure. After 16 weeks, the marked attenuation of fibrosis and promotion of fat regeneration was observed in the PLA + pDA + Tra chamber in contrast to the PLA chamber. Moreover, in contrast to the PLA chamber, Q-PCR results showed that fibrotic factor TGF-β was significantly reduced, associated with a remarkable increase in adipogenic differentiation transcription factors PPAR-γ and C/EBPα in the PLA + pDA + Tra chamber after 16 weeks (p < 0.05). Thus, PLA chambers loaded with pDA + Tra on the surface have good biocompatibility, and chemical anti-fibrosis reagents can synergistically reduce fibrosis formation while excellently promoting adipose tissue regeneration.

Prospects of Biosensors Based on Functionalized and Nanostructured Solitary Materials: Detection of Viral Infections and Other Risks

Advances in nanotechnology over the past decade have emerged as a substitute for conventional therapies and have facilitated the development of economically viable biosensors. Next-generation biosensors can play a significant role in curbing the spread of various viruses, including HCoV-2, and controlling morbidity and mortality. Pertaining to the impact of the current pandemic, there is a need for point-of-care biosensor-based testing as a detection method to accelerate the detection process. Integrating biosensors with nanostructures could be a substitute for ultrasensitive label-free biosensors to amplify sensing and miniaturization. Notably, next-generation biosensors could expedite the detection process. An elaborate description of various types of functionalized nanomaterials and their synthetic aspects is presented. The utility of the functionalized nanostructured materials for fabricating nanobiosensors to detect several types of viral infections is described in this review. This review also discusses the choice of appropriate nanomaterials, as well as challenges and opportunities in the field of nanobiosensors.

A highly selective quinolizinium-based fluorescent probe for cysteine detection

A novel fluorescent quinolizinium-based turn-off probe has been developed for selective detection of cysteine. The probe showed high selectivity and sensitivity towards cysteine over other amino acids including the similarly structured homocysteine and glutathione with a detection limit of 0.18 μM (S/N = 3). It was successfully applied to cysteine detection in living cells with low cytotoxicity and quantitative analysis of spiked mouse serum samples with moderate to good recovery (96-109%).

Microwave mediated synthesis of dopamine functionalized copper sulphide nanoparticles: An effective catalyst for visible light driven degradation of methlyene blue dye

The current work highlights the potential aptitude of copper sulphide (CuS) nanoparticles as cost and energy-effective photo-catalyst for degrading methlyene blue dye under visible light. The surface modified CuS nanoparticles with dopamine (DOP) were prepared by using fast and cost effective microwave assisted methodology. Here, DOP act as biological ligand for the reduction and capping of CuS nanoparticles. The structural and morphological analyses revealed the size controlled synthesis of CuS in presence of DOP with higher thermal stability. The bio-compatibility and non-toxic behaviour of CuS@DOP nanoparticles was evaluated against L929 cell lines and on E. coli and S. aureus strains. The visible light driven photocatalytic activity of the synthesized CuS@DOP was scrutinized for the degradation of methylene blue (MB) dyes, as a model of water contaminants. The photocatalytic degradation of MB by CuS@DOP attained 97% after 10 min of visible light irradiation. The effect of catalyst dose, pH, initial concentration of MB dye, electrolytes, contact time, synergic effect of photolysis and catalysis were studied in detail for optimizing the degradation efficiency of CuS@DOP. The mechanism of CuS@DOP photocatalysis and the formed degraded products were analyzed by using LC/MS technique. The reusability and stability of photocatalyst was confirmed by reusing the catalyst for six successive runs with catalytic performance as high as 80%. Thus, CuS@DOP NPs acted as cost effective, non-toxic visible light driven photo-catalyst for the degradation of organic dye from waste water.

A novel magnetic fluorescent molecularly imprinted sensor for highly selective and sensitive detection of 4-nitrophenol in food samples through a dual-recognition mechanism

In this study, surface imprinting, magnetic separation, and fluorescent detection were integrated to develop a dual-recognition sensor (MF-MIPs), which was used for highly selective and sensitive detection of 4-nitrophenol (4-NP) in food samples. Silane-functionalized carbon dots (Si-CDs) participated in the imprinting process and were uniformly distributed into the MIPs layers. MF-MIPs sensor exhibited a high fluorescence response and selectivity based on the dual-recognition mechanism of imprinting recognition and fluorescence identification. The relative fluorescence intensity of MF-MIPs sensor presented a good linear relationship in the range of 0.08-10 μmol·L^-1 with a low limit of detection (23.45 nmol·L¹) for 4NP. MF-MIPs sensor showed high anti-interference, as well as excellent stability and reusability. The 4-NP recovery from spiked food samples ranged from 93.20 to 102.15%, and the relative standard deviation was lower than 5.0%. Therefore, MF-MIPs sensor may be a promising method for 4-NP detection in food samples.

Au–Ag core–shell composite nanoparticles as a selective and sensitive plasmonic chemical probe for l-cysteine detection in Lens culinaris (lentils)

The present work reported is a simple and selective method for the colorimetrical detection of l-cysteine in Lens culinaris (or lentils) using Au–Ag core–shell (Au core Ag shell) composite nanoparticles as a chemical probe.