Nano-Engineered Surface Comprising Metallic Dendrites for Biomolecular Analysis in Clinical Perspective

Metallic dendrites, a class of three-dimensional nanostructured materials, have drawn a lot of interests in the recent years because of their interesting hierarchical structures and distinctive features. They are a hierarchical self-assembled array of primary, secondary, and terminal branches with a plethora of pointed ends, ridges, and edges. These features provide them with larger active surface areas. Due to their enormous active areas, the catalytic activity and conductivity of these nanostructures are higher as compared to other nanomaterials; therefore, they are increasingly used in the fabrication of sensors. This review begins with the properties and various synthetic approaches of nanodendrites. The primary goal of this review is to summarize various nanodendrites-engineered biosensors for monitoring of small molecules, macromolecules, metal ions, and cells in a wide variety of real matrices. Finally, to enlighten future research, the limitations and future potential of these newly discovered materials are discussed.

MOF-derived Carbon-Coated Cuprous Phosphide Nanosheets for Electrocatalytic Glucose Oxidation

The exploitation of cheap and stable electrode materials to improve the electrocatalytic detection of blood glucose has recently been attracting much attention. Herein, a type of carbon-coated cuprous phosphide (Cu3P)...

Progress of Advanced Nanomaterials in the Non-Enzymatic Electrochemical Sensing of Glucose and H2O2

Non-enzymatic sensing has been in the research limelight, and most sensors based on nanomaterials are designed to detect single analytes. The simultaneous detection of analytes that together exist in biological organisms necessitates the development of effective and efficient non-enzymatic electrodes in sensing. In this regard, the development of sensing elements for detecting glucose and hydrogen peroxide (H₂O₂) is significant. Non-enzymatic sensing is more economical and has a longer lifetime than enzymatic electrochemical sensing, but it has several drawbacks, such as high working potential, slow electrode kinetics, poisoning from intermediate species and weak sensing parameters. We comprehensively review the recent developments in non-enzymatic glucose and H₂O₂ (NEGH) sensing by focusing mainly on the sensing performance, electro catalytic mechanism, morphology and design of electrode materials. Various types of nanomaterials with metal/metal oxides and hybrid metallic nanocomposites are discussed. A comparison of glucose and H₂O₂ sensing parameters using the same electrode materials is outlined to predict the efficient sensing performance of advanced nanomaterials. Recent innovative approaches to improve the NEGH sensitivity, selectivity and stability in real-time applications are critically discussed, which have not been sufficiently addressed in the previous reviews. Finally, the challenges, future trends, and prospects associated with advanced nanomaterials for NEGH sensing are considered. We believe this article will help to understand the selection of advanced materials for dual/multi non-enzymatic sensing issues and will also be beneficial for researchers to make breakthrough progress in the area of non-enzymatic sensing of dual/multi biomolecules.

Multi-color carbon dots for white light-emitting diodes

Single metal-doped CDs with color-tunable properties have been successful synthesized by regulating the precursor molar ratios.

Highly fluorescent Zn-doped carbon dots as Fenton reaction-based bio-sensors: an integrative experimental-theoretical consideration

Heteroatom doped carbon dots (CDs), with high photoluminescence quantum yield (PLQY), are of keen interest in various applications such as chemical sensors, bio-imaging, electronics, and photovoltaics. Zinc, an important element assisting the electron-transfer process and an essential trace element for cells, is a promising metal dopant for CDs, which could potentially lead to multifunctional CDs. In this contribution, we report a single-step, high efficiency, hydrothermal method to synthesize Zn-doped carbon dots (Zn-CDs) with a superior PLQY. The PLQY and luminescence characteristic of Zn-CDs can be tuned by controlling the precursor ratio, and the surface oxidation in the CDs. Though a few studies have reported metal doped CDs with good PLQY, the as prepared Zn-Cds in the present method exhibited a PLQY up to 32.3%. To the best of our knowledge, there is no report regarding the facile preparation of single metal-doped CDs with a QY more than 30%. Another unique attribute of the Zn-CDs is the high monodispersity and the resultant highly robust excitation-independent luminescence that is stable over a broad range of pH values. Spectroscopic investigations indicated that the superior PLQY and luminescence of Zn-CDs are due to the heteroatom directed, oxidized carbon-based surface passivation. Furthermore, we developed a novel and sensitive biosensor for the detection of hydrogen peroxide and glucose leveraging the robust fluorescence properties of Zn-CDs. Under optimal conditions, Zn-CDs demonstrated high sensitivity and response to hydrogen peroxide and glucose over a wide range of concentrations, with a linear range of 10-80 μM and 5-100 μM, respectively, indicating their great potential as a fluorescent probe for chemical sensing.

Rapid green assembly of antimicrobial nanobunches

Antimicrobial nanobunches with different amounts of chitosan-capped Ag were prepared by continuous gas-liquid green route under ultrasound irradiation. Spark-produced aerosol Cu nanoparticles were directly injected into an ultrasound Ag(I)-chitosan reaction cell for efficient hydrosolization of the Cu particles and the subsequent incorporation of Ag and chitosan on Cu. Subsequently, electrospraying was used to form of chitosan-capped Cu-Ag nanobunch coatings. The time required for reducing the bacterial proliferation to 50% dropped to ~1 h at a nanobunch concentration of 10 μg mL⁻¹ from the 2.0 min Ag(I) reaction time, and was further decreased to ~0.5 h by increasing the concentration of the nanobunches to 90 μg mL⁻¹. The nanobunches were directly coated onto the substrate using an electrospray device to fabricate transparent films and composite fibers. The antimicrobial activity of the composite carbon fibers was then evaluated via the disc diffusion method.

Recent developments in nanostructure based electrochemical glucose sensors

Diabetes is a major health problem causing 4 million deaths each year and 171 million people suffering worldwide. Although there is no cure for diabetes, nevertheless, the blood glucose level of diabetic patients should be monitored tightly to avoid further complications. Thus, monitoring of glucose in blood has become an inevitable need leading to fabrication of accurate and sensitive advanced blood sugar detection devices for clinical diagnosis and personal care. It led to the development of enzymatic glucose sensing approach. Later on, various types of nanostructures have been utilized owing to their high surface area, great stability, and cost effectiveness for the fabrication of enzymatic as well as for nonenzymatic glucose sensing approach. This work reviews on both categories, however it is not intended to discuss all the research reports published regarding nanostructure based enzymatic and nonenzymatic approaches between mid-2010 and mid-2015. We, do, however, focused to describe the details of many substantial articles explaining the design of sensors, and utilities of the prepared sensors, so that readers might get the principles behind such devices and relevant detection strategies. This work also focuses on biocompatibility and toxicity of nanomaterials as well as provides a critical opinion and discussions about misconceptions in glucose sensors.

Chitosan-Conjugated Dendritic Ag Nanopowders for Photothermal Therapy Applications

We report the development of Ag nanodendrites where ultrafine Pd particles served as seeds for the subsequent deposition of Ag on their surfaces. By applying chitosan as both a reductant and a stabilizer, chitosan-conjugated Ag dendritic nanopowders were continuously synthesized using a serial system consisting of a spark discharge, an ultrasound-assisted polyol cell, and a collison atomizer with a heated tubular reactor. The resulting materials were then employed to kill cancerous cells photothermally. A spark discharge between Pd electrodes was employed to vaporize Pd components into a N₂ flow, and finally Pd particles were injected into an ultrasound irradiating Ag polyol cell to initiate Ag deposition on incoming Pd primary particles (∼4 nm in lateral dimension). The chitosan-conjugated Ag nanodendrites (∼240 nm in lateral dimension) were formed through collison atomization, and the nanodendrites were employed as sensitizers for photothermal cancerous cell killing under near-infrared irradiation in vitro.

Effective electrocatalysis based on Ag2O nanowire arrays supported on a copper substrate

Silver oxide nanowire arrays (Ag2O NWAs) were first synthesized on a copper (Cu) rod by a simple and facile wet-chemistry approach without using any surfactants. The as-synthesized Ag2O NWA/Cu rod not only can be used as an integrated electrode (called a Ag2O NWA/CRIE) to detect hydrazine (HZ) but also can serve as the catalyst layer for a direct HZ fuel cell. The current density of HZ oxidation on Ag2O NWA (94.4 mA cm(-2)) is much bigger than that on a bare Cu rod (3.9 mA cm(-2)) at -0.6 V, and other Ag2O NWAs have the lowest onset potential (-0.85 V). This suggests that a Ag2O NWA integrated electrode has potential application in catalytic fields that contain the HZ fuel cell.