Tunable synthesis solid or hollow Au-Ag nanostructure, assembled with GO and comparative study of their catalytic properties

In this work, we demonstrated a simple and efficacious two-step method for the synthesis of Ag@Au core-shell nanoparticles （Ag@AuNPs） and the Ag/Au hollow nanocages （Ag/AuNCs） with Ag nanoparticles （AgNPs） as seeds by adjusting pH, and the preparation of hybrid Ag@AuNPs- or Ag/AuNCs-graphene oxide nanocomposites （Ag@AuNPs-GO or Ag/AuNCs-GO） based on the self-assembly. It was noticed from the elec- trostatic assembly experiment that the loading amount of Ag/AuNCs on GO nanosheet was more than that of Ag@AuNPs. The as-synthesized hybrid materials were characterized by transmission electron microscopy, atomic force microscopy, ξ-potential, high-angle annular dark- field scanning transmission electron microscopy, thermo- gravimetric analyzer and X-ray diffraction. Catalytic activities of Ag@AuNPs, Ag/AuNCs and Ag/AuNCs-GO nanostructures were investigated in the reduction of 4-, 3-or 2-nitrophenol to 4-, 3- or 2-aminophenol, and on the basis of comparative kinetic studies the following trend was obtained for the related catalytic activity： Ag/AuNCs- GO 〉 Ag/AuNCs 〉 Ag@AuNPs. These observations were attributed to the simultaneous effects of surface area available for catalytic reaction and composition of the hybrid nanostructures.

Recent Advances in Carbon Nanodots:Properties and Applications in Cancer Diagnosis and Treatment

Cancer is a serious threat to human health.Survival rates of cancer patients are highly dependent on the early diagnosis and treatment.Carbon nanodots(CDs),a rising star of carbon nanomaterial family,can be developed as a promising terrace for cell labeling,bioimaging,drug delivery,diagnosis,and therapy by virtue of many superior properties including unique photo-luminescence properties,low toxicity,excellent biocompatibility,and easy functionalization.In this mini review,we present the recent progress in fundamental properties of CDs,and highlight their bioapplications in cancer diagnosis and treatment.

Nanotechnology Powered CRISPR-Cas Systems for Point of Care Diagnosis and Therapeutic

Inspired by the successful application of Cas9 gene editing for“genome surgery,”we are looking back at what has been accomplished in the ten years of CRISPR editing.Intense effort is now focused on how to utilize the unique functions of CRISPR-Cas systems for molecular diagnostics and the next generation of therapeutic tools.CRISPR-Cas systems have two major advantages for gene editing that render them attractive for these new applications,specifically the ability to easily control their target recognition specificity and to couple this specificity to a targeted or secondary cleavage activity.However,despite the great potential of CRISPR/Cas for both gene editing and diagnosis,its medical applications have yet to be fully realized due factors that limit their delivery or utility for point-of-care(POC)applications.In this editorial note,we discuss how nanotechnology can address challenges associated with new CRISPR applications and what nanotechnology-specific advances are needed to circumvent remaining barriers that limit the development or use of new CRISPR/CAS-based genome editing and diagnostic approaches.

基于核酸探针的光学传感方法和细胞成像研究

许多疾病的特征在于各种生物分子表现出的异常活性,这些物质通常在细胞内外显示过表达现象,因此对其灵敏靶向识别可以提供诊断和治疗效用。由于基因诊疗和化学传感技术的发展,用于灵敏检测细胞内外生物化学物质的核酸探针突显优势。核酸探针可以在稳定进入细胞的同时,特异性地结合目标物质,通过光学方法检测或通过成像技术标识出来。本文综述了采用光学传感方法和成像技术,基于核酸探针检测生物分子的新进展。根据检测对象进行分类,概括分析了几个代表性体系:核酸序列、蛋白质和酶、化学物质和物理化学条件,并详细阐述其关键设计原理、灵敏度及样品检测等结果,同时指出了各类核酸探针的优缺点。

A novel-green adsorbent based on betaine-modified magnetic nanoparticles for removal of methyl blue

A potential adsorbent based on betaine-modified magnetic iron oxide nanoparticles(BMNPs) was successfully synthesized by facile method, characterized and applied for methyl blue(MB) removal from aqueous solution. The characterization results of FTIR, transmission electron microscopy(TEM), X-ray diffraction(XRD) and vibrating sample magnetometer(VSM) showed that the prepared nanoparticles could be well dispersed in water and exhibited excellent superparamagnetism. These properties imply the potential to recycle BMNPs from wastewater through magnetic field. In the adsorption process, the effects of main experimental parameters such as p H of MB solution, initial concentration of MB, contact time, and adsorption capacity for MB were studied and optimized. These results demonstrated that large amounts of quaternary ammonium groups existing on the surface of BMNPs could promote absorption of MB via electrostatic forces. Additionally, the adsorption kinetics of MB was found to follow a pseudosecond-order kinetic model and the adsorption equilibrium data fitted very closely to the Langmuir adsorption isotherm model. The maximum adsorption capacity for MB was calculated to be 136 mg g 1at room temperature. Moreover, the BMNPs showed good reusability with 73.33% MB adsorption in the5 th cycle.

Smart-phone,paper-based fluorescent sensor for ultra-low inorganic phosphate detection in environmental samples

A major goal of environmental agencies today is to conduct point-of-collection monitoring of excess inorganic phosphate(Pi)in environmental water samples for tracking aquatic“dead zones”caused by algae blooms.However,there are no existing commercial devices which have been miniaturized and are suitable for the point-of-need-testing(“PONT”)that is required to fully map a large region,such as the Florida Everglades.To solve this challenge,a reflection-mode fluorescence-sensing apparatus was developed,leveraging an environmentally sensitive fluorophore(MDCC)bound to a bacterial phosphate-binding protein to generate a fluorescent optical signal proportional to the concentration of(Pi)present.The combined end-to-end integrated sensor system had a response time of only 4 s,with minimal effects of common interfering agents and a linear range spanning from 1.1 to 64 ppb.To support easeof-use during PONT,the platform incorporated disposable wax-printed paper strip sample pads and a smartphone camera detection system.Since the EPA threshold is currently 30 ppb to prevent eutrophication,this system serves as a rapid test of whether a region is compliant.

β-Amyloid Biomarker Detection for Alzheimer’s Disease

Alzheimer’s disease(AD)is a neurodegenerative disease.It is a type of dementia and it mainly deals with thinking,memory and behavioral aspects.It is a progressive disease,which in course of time damages most sections of the brain.Beta amyloid peptides(Aβ)have been recognized as potential biomarkers to monitor AD.The Ab protein is made up of 39–42 amino acids,which are the main components of the plaques found in the AD brain.This beta amyloid is toxic to the neurons and causes degeneration.In order to measure these biomarkers,nanobiosensing techniques are used.Timely monitoring of Ab levels helps in the detection of the irreversible disease called AD.These techniques fall in two categories,viz.,in vitro and in vivo.Several techniques like electrochemical techniques,cantilever-based liposome biosensor,ELISA,PET scan,microdialysis,etc.,are discussed further in the article.These techniques can prove to be effective methods for quantifying amyloid deposition within specific brain regions.

A label-free colorimetric assay for detection of c-Myc mRNA based on peptide nucleic acid and silver nanoparticles

A label-free colorimetric protocol based on peptide nucleic acid/silver nanoparticles(PNA/Ag NPs) has been initially proposed for specific recognition of m RNA.Making use of the controlled silver nanoparticles aggregation/dispersion by PNA/PNA–RNA complex, proto-oncogene c-Myc m RNA detection can be achieved. Moreover, the PNA/Ag NPs platform can undergo color change in response to target c-Myc m RNA with single-base-mismatch sensitivity, which could further help in visually identify single nucleotide differences in target genes.

Sweat-Based in Vitro Diagnostics(IVD):From Sample Collection to Point-of-Care Testing(POCT)

Sweat-based diagnostics offer an exciting avenue to noninvasively monitor analytes which had previously only been avail-able through painful blood draws.Sweat is enriched with physiologically valuable information,and recent proteomic studies have identified numerous critical analytes which have highly correlated levels in blood,interstitial fluid and sweat.How-ever,usage of sweat for health monitoring has not been studied extensively due to the substantial challenge of assembling a composite clinic-ready device.Recent advances in soft electronics have made this goal realizable,as these devices can perform electronic or optical monitoring on a flexible substrate using small volumes of liquid.While this field is still in its infancy,this review examines the physiological composition of sweat,various improvements in material science that improve sensor design,existing FDA approvals,methods of extracting sweat and comparisons to blood-based tests.Furthermore,this review assesses the critical challenges which must be overcome for this type of technology to make it out of research laboratories and into continuous clinical use.We believe that once properly harnessed,sweat-based diagnostics can provide patients a painless monitoring tool which can be customized to track a wide variety of medical conditions from the comfort of a patient’s own home.

Microfluidic Electrochemical Devices for Biosensing

The integration of the electrochemical detection system together with microfluidic technology is an attractive choice for the construction of miniaturized components in a single platform.Microchannel networks fabricated on conductive substrates prevent environmental contaminants and require only a tiny(μL or nL)sample for electroanalysis.Microfluidics coupled electrochemical detection system is particularly advantageous compared to traditional electrochemical sensing systems due to its flexibility,rapid analysis,low fabrication costs,ease of implementation and disposability.With these electrochemical sensing platforms,biochemical assays that require complex pre-processing of biological samples can be conducted on a chip.In this review,a comprehensive overview of the basic concepts of microfluidics and its recent applications in the design of miniaturized electrochemical sensors for biosensing applications are presented.

Special Topic:Point-of-Care Testing(POCT)and In Vitro Diagnostics(IVDs)

In last two decades,substantial efforts have been made to develop in vitro diagnostic(IVD)technologies.Their distinct features,including:rapid results,reduced patient discomfort,simplicity,cost-effectiveness,enablement of early diagnosing and accessibility in remote areas,make these technologies attractive to the medical profession.IVD tests are generally performed on biological samples such as blood,sweat,urine or tissue,in a controlled environment outside a living organism,with the goal of obtaining a diagnosis from the assays.

An insight into the cells' glycans and lectin-glycosensing sites

Glycosylation produces a diverse and abundant repertoire of glycans that help protein folding and cellular secretion[1].Glycoproteins often sprout sialic acid(alias N-acetyl neuraminic acid,abbreviated as Neu5Ac)at the termini of their N-and O-glycans in a process called sialylation[2].Alterations to the normal function of the glycosylation machinery,including increased branching of N-linked glycans and sialylation,are major hallmarks of cancer progression.Particularly,increased sialylation on the

PC12 cell integrated biosensing neuron devices for evaluating neuronal exocytosis function upon silver nanoparticles exposure

In this research, we explored a rapid assessment of silver nanoparticles(Ag-NPs) neurotoxicity at a single-cell level. Traditional nanotoxicity assays on large cell-populations may hide the important heterogeneity of individual cells often found in neuronal cells. The development in the area of new nanomaterial discoveries is far ahead of the development of advanced tools to measure these materials' toxicity. Development of alternative approaches to assess nanomaterials toxicity rapidly, reliably, and accurately is desirable. Here, we present a chip-based, cell-integrated microwell-array device for rapid assessment of neurotoxicity of Ag-NPs by monitoring the exocytosis function of a PC12 cell. Results presented here confirm the dose-dependent toxicity of Ag-NPs and the immediate alteration of their exocytosis function when exposed to NPs.