A carbon quantum dot-decorated g-C3N4 composite as a sulfur hosting material for lithium-sulfur batteries

Although lithium-sulfur (Li-S) batteries have attracted strong consideration regarding their fundamental mechanism and energy applications, the inferior cycling performance and low reaction rate caused by the "shuttling effect" and the sluggish reaction kinetics of lithium polysulfides (LiPSs) impede their practical application. In this work, graphitic C3N4 (g-C3N4) assembled with highly-dispersed nitrogen-containing carbon quantum dots (CQDs) is designed as a cooperative catalyst to accelerate the reaction kinetics of LiPS conversion, the precipitation of Li2S during discharging, and insoluble Li2S decomposition during the charging process. Meanwhile, the introduction of CQDs improves the conductivity of the g-C3N4 substrate, showing great significance for the construction of high-performance electrocatalysts. As a result, the as-obtained composite shows efficient adsorption and electrochemical conversion of LiPSs, and the Li-S batteries assembled with CQDs/g-C3N4 exhibit an initial specific capacity of 1300.0 mA h g-1 at the current density of 0.1C and retain 582.3 mA h g-1 after 200 cycles. The electrode with the modified composite displays a greater capacity contribution of Li2S precipitation (175.7 mA h g-1), indicating an enhanced catalytic activity of g-C3N4 decorated by CQDs. The rational design of CQDs/g-C3N4 as a sulfur host could be an effective strategy for developing high performance Li-S batteries.

Effect of plasmonic excitation on mature insulin amyloid fibrils

Interactions between amyloid protein structures and nanomaterials have been extensively studied to develop effective inhibitors of amyloid aggregation. Limited investigations are reported on the impact of nanoparticles on mature fibrils. In this work, gold nanoparticles are used as photothermal agents to alter insulin fibrils. To this end, gold colloids bearing a negatively charged capping shell, with an average diameter of 14 nm and a plasmon resonance maximum at 520 nm are synthesized. The effects on mature insulin fibril morphology and structure upon plasmonic excitation of the nanoparticles-fibril samples have been monitored by spectroscopic and microscopic methods. The obtained data indicate that an effective destruction of the amyloid aggregates occur upon irradiation of the plasmonic nanoparticles, allowing the development of emerging strategies to alter the structure of amyloid fibrils.

Current Progress in Aptasensor for Ultra-Low Level Monitoring of Parkinson's Disease Biomarkers

In today's world, Parkinson's disease (PD) has been introduced as a long-term degenerative disorder of the central nervous system which mainly affects approximately more than ten million people worldwide. The vast majority of diagnostic methods for PD have operated based on conventional sensing platforms, while the traditional laboratory tests are not efficient for diagnosis of PD in the early stage due to symptoms of this common neurodegenerative syndrome starting slowly. The advent of the aptasensor has revolutionized the early-stage diagnosis of PD by measuring related biomarkers due to the myriad advantages of originating from aptamers which can be able to sensitive and selective capture various types of related biomarkers. The progress of numerous sensing platforms and methodologies in terms of biosensors based on aptamer application for PD diagnosis has revealed promising results. In this review, we present the latest developments in myriad types of aptasensors for the determination of related PD biomarkers. Working strategies, advantages and limitations of these sensing approaches are also mentioned, followed by prospects and challenges.

Sensitive photoelectrochemical determination of T4 polynucleotide kinase using AuNPs/SnS2/ZnIn2S4 photoactive material and enzymatic reaction-induced DNA structure switch strategy

We report here Au nanoparticles (AuNPs)/SnS₂/ZnIn₂S₄ as a high-performance active material for sensitive photoelectrochemical (PEC) determination of T4 polynucleotide kinase (T4 PNK) using an enzymatic reaction-induced DNA structure switch strategy. To construct the PEC biosensor, a double-stranded DNA probe consisting of a CdS quantum dots (QDs)-labeled single-stranded DNA (sDNA) and its complementary DNA (cDNA) is immobilized on the AuNPs/SnS₂/ZnIn₂S₄ photoactive material. T4 PNK can catalyze the phosphorylation of 5'-OH-terminated sDNA in the double-stranded DNA probe when ATP is present, and λ-exonuclease can catalyze the degradation of the phosphorylated sDNA into small fragments. Then the cDNA forms a hairpin structure so that CdS QDs and AuNPs are in close contact, which can induce exciton-plasma interactions between CdS QDs and AuNPs. The exciton-plasma interactions significantly boost the photocurrent, enabling the "signal on" PEC determination of T4 PNK in the range of 10^-4 - 1 U mL^-1 with a detection limit of 6 × 10^-5 U mL^-1. The PEC biosensor can also be used to screen enzyme inhibitors.

In Situ Formation of Bi2MoO6-Bi2S3 Heterostructure: A Proof-Of-Concept Study for Photoelectrochemical Bioassay of l-Cysteine

A novel signal-increased photoelectrochemical (PEC) biosensor for l-cysteine (L-Cys) was proposed based on the Bi₂MoO₆–Bi₂S₃ heterostructure formed in situ on the indium–tin oxide (ITO) electrode. To fabricate the PEC biosensor, Bi₂MoO₆ nanoparticles were prepared by a hydrothermal method and coated on a bare ITO electrode. When L-Cys existed, Bi₂S₃ was formed in situ on the interface of the Bi₂MoO₆/ITO electrode by a chemical displacement reaction. Under the visible light irradiation, the Bi₂MoO₆–Bi₂S₃/ITO electrode exhibited evident enhancement in photocurrent response compared with the Bi₂MoO₆/ITO electrode, owing to the signal-increased sensing system and the excellent property of the formed Bi₂MoO₆–Bi₂S₃ heterostructure such as the widened light absorption range and efficient separation of photo-induced electron–hole pairs. Under the optimal conditions, the sensor for L-Cys detection has a linear range from 5.0 × 10⁻¹¹ to 1.0 × 10⁻⁴ mol L⁻¹ and a detection limit of 5.0 × 10⁻¹² mol L⁻¹. The recoveries ranging from 90.0% to 110.0% for determining L-Cys in human serum samples validated the applicability of the biosensor. This strategy not only provides a method for L-Cys detection but also broadens the application of the PEC bioanalysis based on in situ formation of photoactive materials.

Non-Noble Plasmonic Metal-Based Photocatalysts

Solar-to-chemical energy conversion via heterogeneous photocatalysis is one of the sustainable approaches to tackle the growing environmental and energy challenges. Among various promising photocatalytic materials, plasmonic-driven photocatalysts feature prominent solar-driven surface plasmon resonance (SPR). Non-noble plasmonic metals (NNPMs)-based photocatalysts have been identified as a unique alternative to noble metal-based ones due to their advantages like earth-abundance, cost-effectiveness, and large-scale application capability. This review comprehensively summarizes the most recent advances in the synthesis, characterization, and properties of NNPMs-based photocatalysts. After introducing the fundamental principles of SPR, the attributes and functionalities of NNPMs in governing surface/interfacial photocatalytic processes are presented. Next, the utilization of NNPMs-based photocatalytic materials for the removal of pollutants, water splitting, CO₂ reduction, and organic transformations is discussed. The review concludes with current challenges and perspectives in advancing the NNPMs-based photocatalysts, which are timely and important to plasmon-based photocatalysis, a truly interdisciplinary field across materials science, chemistry, and physics.

Application electrochemical sensor based on nanosheets G-C3N4/CPE by square-wave anodic stripping voltammetric for measure amounts of toxic tartrazine color residual in different drink and foodstuffs

The present work describes a method (SWASV) techniques for measure of tartrazine color a harmful compound present in real samples, and the extremely harmful to humans and animals even at low concentrations using G-C₃N₄ nanosheets sensor. Here, we report the use of an electrochemical approach for analytical determination of toxic tartrazine that takes 150 s. The calibration curve was linear in range of the (0.02-18.0 µmol L^-1). The current response was linearly proportional to the tartrazine concentration with a R²∼ 0.999. We demonstrated a sensitivity a limit of detection of (0.022 µmol L^-1). Finally, sensor nanosheets G-C₃N₄/CPE introduced to measure toxic tartrazine in different drink and foodstuff samples was used and the chemical nanosheets G-C₃N₄/CPE sensor made it possible as an excellent sensor with reproducibility for determination other samples.

POD Nanozyme optimized by charge separation engineering for light/pH activated bacteria catalytic/photodynamic therapy

The current feasibility of nanocatalysts in clinical anti-infection therapy, especially for drug-resistant bacteria infection is extremely restrained because of the insufficient reactive oxygen generation. Herein, a novel Ag/Bi₂MoO₆ (Ag/BMO) nanozyme optimized by charge separation engineering with photoactivated sustainable peroxidase-mimicking activities and NIR-II photodynamic performance was synthesized by solvothermal reaction and photoreduction. The Ag/BMO nanozyme held satisfactory bactericidal performance against methicillin-resistant Staphylococcus aureus (MRSA) (~99.9%). The excellent antibacterial performance of Ag/BMO NPs was ascribed to the corporation of peroxidase-like activity, NIR-II photodynamic behavior, and acidity-enhanced release of Ag⁺. As revealed by theoretical calculations, the introduction of Ag to BMO made it easier to separate photo-triggered electron-hole pairs for ROS production. And the conduction and valence band potentials of Ag/BMO NPs were favorable for the reduction of O₂ to ·O₂⁻. Under 1064 nm laser irradiation, the electron transfer to BMO was beneficial to the reversible change of Mo⁵⁺/Mo⁶⁺, further improving the peroxidase-like catalytic activity and NIR-II photodynamic performance based on the Russell mechanism. In vivo, the Ag/BMO NPs exhibited promising therapeutic effects towards MRSA-infected wounds. This study enriches the nanozyme research and proves that nanozymes can be rationally optimized by charge separation engineering strategy.

Ag0 decorated Cr2S3 NPs embedded on PVP matrix: A colorimetric probe for selective and rapid detection of sulphide ions from environmental samples

Globally, the environmental pollution is one of the major issues causing toxicity towards human and aquatic life. We have developed a facile and innovative sensing approach for detection of sulphide ions (S^2-) present in the aqueous media using Ag⁰ decorated Cr₂S₃ NPs embedded on PVP matrix (Ag/Cr₂S₃-PVP). Based on the SPR phenomena, the detection of S^2- ions was established. The nanohybrid was characterized using various techniques such as UV-vis spectrophotometer, High-Resolution Transmission Electron Microscopy (HR-TEM), Thermal Gravimetric Analysis (TGA), X-ray diffraction analysis(XRD), Energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The yellowish colour of Ag/Cr₂S₃-PVP nanohybrid turned to brown colour in presence of S^2- ions. The selectivity and sensitivity of the prepared probe was studied against the other interfering metal ions. In addition, the effect of different concentration of S^2- ions in the nanohybrid solution was investigated and the Limit of detection (LOD) was found to be 6.6 nM. The good linearity was found over the range of 10 nM to 100 μM with R² value of 0.981. The paper strip based probe was developed for rapid onsite monitoring of S^2- ions. The proposed method is found to be cost-effective, rapid, and simple. We have validated the practical applicability of the prepared probe for determining the concentration of S^2- ions in real water samples.

Detection of monoamine oxidase B using dark-field light scattering imaging and colorimetry

Detection of MAO-B using dark-field light scattering imaging and colorimetry based on localized surface plasmon resonance induced by silver deposited gold nanostars.

Surface Plasmon Coupling Electrochemiluminescence Immunosensor Based on Polymer Dots and AuNPs for Ultrasensitive Detection of Pancreatic Cancer Exosomes

Polymer dots (Pdots) have become attractive electrochemiluminescence (ECL) luminophores due to their facile synthesis, easy modification, and stable electrochemical and optical properties. However, their ECL efficiency is not high enough for practical applications. In this work, we proposed an ECL immunosensor based on localized surface plasmon resonance (LSPR) between AuNPs and Pdots for the determination of pancreatic cancer exosomes. Based on the finite-difference time-domain simulations and the band energy of Pdots and AuNPs, we proposed the possible LSPR mechanism. The hot electrons of plasmonic AuNPs were photoexcited to surface plasmon states by ECL emission of Pdots, and then the excited hot electrons were transferred to the conduction band of Pdots, which significantly improved the ECL efficiency of Pdots. The ECL immunosensor displayed a wide calibration range of 1.0 × 10³ to 1.0 × 10⁶ particles/mL with a detection limit of 400 particles/mL. Cancer-related protein profiling revealed high selectivity toward different expressions of exosomal surface proteins from PANC-01, HeLa, MCF-7, and HPDE6-C7 cell lines. The proposed ECL system exhibits a promising prospect for protein biomarker profiling and early cancer-related diagnosis.

The electrochemical detection of prostate specific antigen on glassy carbon electrode modified with combinations of graphene quantum dots, cobalt phthalocyanine and an aptamer

Herein, a novel aptasensor is developed for the electrochemical detection of prostate specific antigen (PSA) on electrode surfaces modified using various combinations of a Cobalt phthalocyanine (CoPc), an aptamer and graphene quantum dots (GQDs). Electrochemical impedance spectroscopy (EIS) as well as differential pulse voltammetry (DPV) are employed for the detection of PSA. In both analytical techniques, linear calibration curves were observed at a concentration range of 1.2-2.0 pM. The glassy carbon electrode where CoPc and GQDs are placed on the electrode when non-covalently linked followed by addition of the aptamer (GQDs-CoPc(ππ)-aptamer (sequential)) showed the best performance with a limit of detection (LoD) as low as 0.66 pM when using DPV. The detection limits were much lower than the dangerous levels reported for PSA in males tested for prostate cancer. This electrode showed selectivity for PSA in the presence of bovine serum albumin, glucose and L-cysteine. The aptasensor showed good stability, reproducibility and repeatability, deeming it a promising early detection device for prostate cancer.

Self-passivated CuV2O6 as a universal photoelectrode material for reliable and accurate photoelectrochemical sensing

Photoelectrochemical (PEC) detection has attracted intensive attention during the past decade. Currently, most research focuses on improving the sensitivity and selectivity of the PEC sensor, but the issue of the stability of the photoelectrode material under the testing environment is often ignored or lacks in-depth investigation. Herein, we develop a novel CuV2O6 photoelectrode exhibiting superior stability under the testing environment through self-passivation. CuV2O6-based PEC sensors are fabricated for the first time for highly selective carcinoembryonic antigen (CEA) and human serum alpha fetoprotein (AFP) detection. The CuV2O6 shows great potential as a universal photoelectrode material for reliable and accurate PEC detection of macromolecules.

Continuous in situ portable SERS analysis of pollutants in water and air by a highly sensitive gold nanoparticle-decorated PVDF substrate

The increasingly serious environmental pollution worldwide has posed a great threat to the ecosystem and human health, and yet the development of portable in situ monitoring techniques that are sensitive to gaseous and water pollutants remains incomplete. Herein, we report a highly active surface-enhanced Raman spectroscopy (SERS) substrate fabricated by immobilizing gold nanoparticles (AuNPs) onto a polyvinylidene fluoride (PVDF) membrane for continuous in situ SERS detection of pollutants in water and atmosphere. 4-Mercaptobenzoic acid (4-MBA) was adopted as a probe molecule to evaluate the performance of the substrate, and the results indicate that the polymer-based flexible substrate features high sensitivity, uniformity, and repeatability. The fabricated PVDF/SERS substrate was integrated with a portable Raman spectrometer operating under both passing-by and passing-through modes. The integrated system accomplishes quantitative detection and real-time online monitoring of pH in a liquid environment with a response speed of less than 10 s and the rapid SERS response to gas molecules at a low concentration within 30 s. We also demonstrated the highly sensitive detection for mainstream smoke (MS) and sidestream (SS) of cigarette smoke and verified their differences in the main constituent which contributes to the harmful secondhand smoke in public. The developed portable Raman system has excellent application prospects in online liquid and gas environmental detection.

Ultrasensitive photoelectrochemical platform with micro-emulsion-based p-type hollow silver iodide enabled by low solubility product (Ksp) for H2S sensing

Since visible-light (VL) accounting for massive solar radiation energy, a large amount of attention has been paid to the development of highly efficient visible-light-driven (VLD) semiconductor materials. However, despite recent efforts to construct VL active material, hollow structure-based silver iodide (AgI) with appropriate band gap and a large surface area are limited because of lack of a proper synthesis method. Herein, hollow AgI with p-type semiconductor behavior is constructed on the basis of micro-emulsion strategy, which enables admirable cathode photoelectrochemical (PEC) response. The as-prepared hollow AgI is applied to fabricate the PEC sensing platform and reveals a low limit of detection of 0.04 fM and a wide dynamic range up to 5 orders of magnitude toward H₂S. The PEC sensing mechanism is supposed to the 'signal-off' pattern on account of the ultralow solubility product (K_sp) of Ag₂S, derived from the precipitation reaction due to the high affinity between sulfide ion and Ag⁺. Besides, the hollow structure of AgI provides sufficient surface area forin situproducing Ag₂S that serves as recombination center of carrier, thus causing the efficient quenching of photocurrent signals. This work broadens the horizon of structuring VLD semiconductor nanomaterials andK_sp-based H₂S sensing.

Aptamer-based sensing of breast cancer biomarkers: a comprehensive review of analytical figures of merit

INTRODUCTION

Accurate determination of the aberrantly expressed biomarkers such as human epidermal growth factor receptor 2 (HER2), carcinoembryonic antigen (CEA), platelet-derived growth factor (PDGF), mucin 1 (MUC1), and vascular endothelial growth factor VEGF₁₆₅ have played an essential role in the clinical management of the breast cancer. Assessment of these cancer-specific biomarkers has conventionally relied on time-taking methods like the enzyme-linked immunosorbent assay and immunohistochemistry. However, recent development in the aptamer-based diagnostics has allowed developing tools that may substitute the conventional means of biomarker assessment in breast cancer. Adopting the aptamer-based diagnostic tools (aptasensors) to clinical practices will depend on their analytical performance on clinical samples.

AREAS COVERED

In this review, we provide an overview of the analytical merits of HER2, CEA, PDGF, MUC1, and VEGF₁₆₅ aptasensors. Scopus and Pubmed databases were searched for studies reporting aptasensor development for the listed breast cancer biomarkers in the past one decade. Linearity, detection limit, and response time are emphasized.

EXPERT OPINION

In our opinion, aptasensors have proven to be on a par with the antibody-based methods for detection of various breast cancer biomarkers. Though robust validation of the aptasensors on significant sample size is required, their ability to detect pathophysiological range of biomarkers suggest the possibility of future clinical adoption.

Gold based nano-photonic approach for point-of-care detection of circulating long non-coding RNAs

Development of a rapid, sensitive and easy to use point of care assay for detection of circulating long non-coding RNAs (lncRNAs) is of great importance. These biomolecules possess the ability to regulate vital cellular processes and act as biomarkers for various human non-communicable diseases. The present work aimed to develop a simplified and reliable cytometric fluorescence-based approach for precise recognition of circulating lncRNAs in a given sample using biotinylated uracil-modified oligonucleotide tethered AlexaFluor488-labeled streptavidin gold colloidal (BiO-StrAG) nano-conjugates. The fluorophores in close proximity to the gold nanoparticles result in quenching of fluorescence; however, specific recognition of target lncRNAs increases this distance which causes plasmonic enhancement of fluorescence. As per the flow cytometry and fluorometry investigations, the developed methodology provides a precise and sensitive approach for detection of the target lncRNAs (up to 5 nM in any given sample). With advantages of high selectivity and feasibility, our strategy offers great potential of being developed as a promising tool for interrogating aberrant regulation of lncRNAs functions, especially indicated in various diseased states.

Synergizing Functional Nanomaterials with Aptamers Based on Electrochemical Strategies for Pesticide Detection: Current Status and Perspectives

Owing to the high toxicity and large-scale use of pesticides, it is imperative to develop selective, sensitive, portable, and convenient sensors for rapid monitoring of pesticide. Therefore, the electrochemical detection platform offers a promising analytical approach since it is easy to operate, economical, efficient, and user-friendly. Meanwhile, with advances in functional nanomaterials and aptamer selection technologies, numerous sensitivity-enhancement techniques alongside a widespread range of smart nanomaterials have been merged to construct novel aptamer probes to use in the biosensing field. Hence, this study intends to highlight recent development and promising applications on the functional nanomaterials with aptamers for pesticides detection based on electrochemical strategies. We also reviewed the current novel aptamer-functionalized microdevices for the portability of pesticides sensors. Furthermore, the major challenges and future prospects in this field are also discussed to provide ideas for further research.

Nanostructure-based photoelectrochemical sensing platforms for biomedical applications

As a newly developed and powerful analytical method, the use of photoelectrochemical (PEC) biosensors opens up new opportunities to provide wide applications in the early diagnosis of diseases, environmental monitoring and food safety detection. The properties of diverse photoactive materials are one of the essential factors, which can greatly impact the PEC performance. The continuous development of nanotechnology has injected new vitality into the field of PEC biosensors. In many studies, much effort on PEC sensing with semiconductor materials is highlighted. Thus, we propose a systematic introduction to the recent progress in nanostructure-based PEC biosensors to exploit more promising materials and advanced PEC technologies. This review briefly evaluates the several advanced photoactive nanomaterials in the PEC field with an emphasis on the charge separation and transfer mechanism over the past few years. In addition, we introduce the application and research progress of PEC sensors from the perspective of basic principles, and give a brief overview of the main advances in the versatile sensing pattern of nanostructure-based PEC platforms. This last section covers the aspects of future prospects and challenges in the nanostructure-based PEC analysis field.

An aptasensor using ceria electrodeposited-screen-printed carbon electrode for detection of epithelial sodium channel protein as a hypertension biomarker

Epithelial sodium channel (ENaC) is a transmembrane protein that has an essential role in maintaining the levels of sodium in blood plasma. A person with a family history of hypertension has a high enough amount of ENaC protein in the kidneys or other organs, so that the ENaC protein acts as a marker that a person is susceptible to hypertension. An aptasensor involves aptamers, which are oligonucleotides that function similar to antibodies, as sensing elements. An electrochemical aptasensor for the detection of ENaC was developed using a screen-printed carbon electrode (SPCE) which was modified by electrodeposition of cerium oxide (CeO2). The aptamer immobilization was via the streptavidin-biotin system. The measurement of changes in current of the active redox [Fe(CN)6]3-/4- was carried out by differential pulse voltammetry. The surfaces of SPCE and SPCE/CeO2 were characterized using scanning electron microscopy, voltammetry and electrochemical impedance spectroscopy. The Box-Behnken experimental optimization design revealed the streptavidin incubation time, aptamer incubation time and streptavidin concentrations were 30 min, 30 min and 10.8 µg ml-1, respectively. Various concentrations of ENaC were used to obtain the linearity range of 0.05-3.0 ng ml-1, and the limits of detection and quantification were 0.012 ng ml-1 and 0.038 ng ml-1, respectively. This aptasensor method has the potential to measure the ENaC protein levels in urine samples as well as to be a point-of-care device.

ZnO-reduced graphene oxide composite based photoelectrochemical aptasensor for sensitive Cd(II) detection with methylene blue as sensitizer

In this paper a photoelectrochemical (PEC) aptasensor based on specific recognition with conformational changed after the target Cd(II) identification was fabricated. A ZnO and reduced graphene oxide (ZnO-rGO) nanocomposite with enhanced PEC activity was designed as photoactive material. After the further incorporation of gold nanoparticles (AuNPs) with ZnO-rGO nanocomposite, the enhanced photocurrent signal could be detected owing to the localized surface plasmon resonance and good conductivity of AuNPs. In addition, AuNPs were used as anchors for immobilization of -SH modified aptamer S1. After that aptamer S2 was paired with S1 sequence to form complementary double stranded DNA (dsDNA) on the electrode surface. Methylene blue (MB) was acted as sensitizer and assembled in dsDNA structure to amplify photocurrent response. When Cd(II) was bound to the aptamer presented on the sensing interface, S2 specifically recognized and captured Cd(II), which resulted in the unwinding of dsDNA structure and the separation of MB molecules from the electrode surface with photocurrent response decreased. The photocurrent was detected by a double-working-electrode system, which used the modified electrode as the first working electrode and glassy carbon electrode (GCE) as the second working electrode. Dopamine (DA) was added to the electrolyte and acted as the electron donor, which could be oxidized on the modified electrode and reduced on the GCE to form a cyclic reaction, leading to the enhanced photocurrent response with improved photocurrent stability. This MB sensitized PEC aptasensor exhibited a high sensitivity with a detection limit of 1.8 × 10^-12 mol/L (3σ). Thus, a highly sensitive aptasensor with double-working-electrode detection method for Cd(II) determination were established and further applied to the water samples analysis.

Coordination-induced exfoliation to monolayer Bi-anchored MnB2 nanosheets for multimodal imaging-guided photothermal therapy of cancer

Background: Rapid advance in biomedicine has recently vitalized the development of multifunctional two-dimensional (2D) nanomaterials for cancer theranostics. However, it is still challenging to develop new strategy to produce new types of 2D nanomaterials with flexible structure and function for enhanced disease theranostics. Method: We explore the monolayer Bi-anchored manganese boride nanosheets (MBBN) as a new type of MBene (metal boride), and discover their unique near infrared (NIR)-photothermal and photoacoustic effects, X-ray absorption and MRI imaging properties, and develop them as a new nanotheranostic agent for multimodal imaging-guided photothermal therapy of cancer. A microwave-assisted chemical etching route was utilized to exfoliate the manganese boride bulk into the nanosheets-constructed flower-like manganese boride nanoparticle (MBN), and a coordination-induced exfoliation strategy was further developed to separate the MBN into the dispersive monolayer MBBN by the coordination between Bi and B on the surface, and the B-OH group on the surface of MBBN enabled facile surface modification with hyaluronic acid (HA) by the borate esterification reaction in favor of enhanced monodispersion and active tumor targeting. Result: The constructed MBBN displays superior NIR-photothermal conversion efficiency (η=59.4%) as well as high photothermal stability, and possesses versatile imaging functionality including photoacoustic, photothermal, CT and T1 -wighted MRI imagings. In vitro and in vivo evaluations indicate that MBBN had high photothermal ablation and multimodal imaging performances, realizing high efficacy of imaging-guided cancer therapy. Conclusion: We have proposed new MBene concept and exfloliation strategy to impart the integration of structural modification and functional enhancement for cancer theranostics, which would open an avenue to facile fabrication and extended application of multifunctional 2D nanomaterials.

Two-dimensional transition metal dichalcogenides assisted biofunctionalized optical fiber SPR biosensor for efficient and rapid detection of bovine serum albumin

The present study reports an alternative method of functionalizing the optical fiber Surface Plasmon Resonance (SPR) sensing probe with antibodies for label-free detection of bovine serum albumin (BSA) protein. In this novel approach, the gold coated fiber was first modified with Molybdenum disulfide (MoS₂) nanosheets followed by its bio-functionalization with Anti-BSA antibodies. The developed technique not only allowed the amplification of the SPR signals by synergic effects of MoS₂ and gold metallic thin film but also enabled a direct and chemical-free attachment of representative antibodies through hydrophobic interactions. The sensitivity of the MoS₂ modified sensing probe with detection limit of 0.29 µg/mL was improved as compared to the fiber optic SPR biosensor without MoS₂ overlayer (Detection limit  for BSA was 0.45 μg/mL). The developed biosensor has good specificity, and environmental stability. Accordingly, the proposed design of the MoS₂ based SPR optical biosensor can offer the development of a simplified optical device for the monitoring of various biomedical and environmental parameters.

A surface plasmon resonance enhanced photoelectrochemical immunoassay based on perovskite metal oxide@gold nanoparticle heterostructures

A visible light-driven photoelectrochemical immunoassay was designed for PSA detection by using perovskite metal oxide@gold nanoparticle heterostructures.

Target-triggered dynamic hairpin assembly for signal amplification of microRNA and oncogenes and its application in live-cell imaging

DNA nanobrushes are constructed based on target-triggered dynamic hairpin assembly in both unidirectional and bilateral growth manners, and realize sensitive and selective detection of short miRNA and long target DNA, respectively.

Employing AgNPs doped amidoxime-modified polyacrylonitrile (PAN-oxime) nanofibers for target induced strand displacement-based electrochemical aptasensing of CA125 in ovarian cancer patients

In this study, a high-performance biosensing nanoplatform based on amidoxime-modified polyacrylonitrile nanofibers decorated with Ag nanoparticles (AgNPs-PAN-oxime NFs) is described. The AgNPs-PAN-oxime NFs were prepared by the combination of electrospinning technique and chemical modification of nitrile group in the PAN. The proposed signal amplifiying nanoplatform was applied in the fabrication of an electrochemical aptasensor for the sensitive detection of CA 125 based on aptamer-cDNA duplex and target induced strand displacement recognition mechanism. The aptasensing interface offers high sensitivity and selectivity for detection of tumor marker due to inherent advantages such as high specific surface area of NFs, good conductivity by doping AgNPs into the polymer NFs and especially the ideal selectivity of anti CA 125 aptamer to its target. The electrochemical aptasensor revealed a wide dynamic linear range (DLR) from 0.01 to 350 U mL^-1 with a correlation coefficient of 0.991 and limit of detection (LOD) of 0.0042 U mL^-1. Additionally, the designed aptasensor showed acceptable selectivity, reproducibility, repeatability and stability. The satisfactory results for determination of CA 125 in serum samples compared to ELISA method (p-value > 0.05) indicated the potential application of aptasensor in clinical monitoring of tumor biomarker for early diagnosis and management of ovarian cancer.

Construction of Acetaldehyde-Modified g-C3N4 Ultrathin Nanosheets via Ethylene Glycol-Assisted Liquid Exfoliation for Selective Fluorescence Sensing of Ag. ACS APPLIED MATERIALS & INTERFACES 2018;10:44624-44633. [PMID: 30511564 DOI: 10.1021/acsami.8b15501]

We successfully prepared acetaldehyde-modified graphitic carbon nitride (g-C₃N₄) ultrathin nanosheets (ACNNSs) by a simple ethylene glycol-assisted liquid exfoliation method. The introduction of acetaldehyde regulated the surface energy of g-C₃N₄ to better match with that of water, which improved the exfoliation efficiency. Moreover, acetaldehyde introduces defects into the g-C₃N₄ structure, which can act as excitation energy traps and cause considerable variation in the fluorescence emission. Benefiting from the stable photoluminescence emission, good water solubility, and biocompatibility, the obtained ACNNSs showed a selective fluorescent response to Ag⁺ in both aqueous solution and living cells. The strong absorption and intimate contact with Ag⁺ and its appropriate redox potential of ACNNSs contributed to this excellent fluorescent response. A simple and environmental friendly approach was proposed to simultaneously achieve modification and exfoliation of g-C₃N₄ in aqueous solution. These findings might lead to wider applications of carbon-based nanomaterials as active materials for fluorescence detection in the environment.

Hydrodynamic Layer-by-Layer Assembly of Transferable Enzymatic Conductive Nanonetworks for Enzyme-Sticker-Based Contact Printing of Electrochemical Biosensors

Realizing high-performance electrochemical biosensors in a simple contact-printing-based approach significantly increases the applicability of integrated flexible biosensors. Herein, an enzyme-sticker-based approach that enables flexible and multielectrochemical sensors via simple contact-transfer printing is reported. The enzyme sticker consists of an enzymatic conductive network film and a polymeric support. The enzyme-incorporated nanostructured conductive network showing an efficient electrical coupling was assembled via the hydrodynamic layer-by-layer assembly of redox enzymes, polyelectrolytes, single-walled carbon nanotubes, and a biological glue material, M13 phage. The enzymatic conductive network on a polymeric membrane support was facilely wet contact-transfer printed onto integrated electrode systems by exploiting varying degrees of hydrophilicity displayed by the enzymatic electronic film, polymeric support, and receiving electrodes of the sensor system. The glucose sensors fabricated using the enzyme sticker detected glucose at a concentration of as low as 35 μM and showed high selectivity and stability. Furthermore, a flexible dual-sensor array capable of detecting both glucose and lactate was demonstrated using the versatile enzyme sticker concept. This work presents a new route toward assembling and integrating hybrid nanomaterials with efficient electrochemical coupling for high-performance biosensors and health-monitoring devices as well as for emerging bioelectronics and electrochemical devices.

A ratiometric photoelectrochemical immunosensor based on g-C3N4@TiO2 NTs amplified by signal antibodies–Co3O4 nanoparticle conjugates

Herein, we report a ratiometric photoelectrochemical (PEC) immunosensor coupled with secondary antibodies–Co₃O₄ nanoparticle conjugates (Ab₂–Co₃O₄ NPs) for signal amplification.