Cardiac troponin I photoelectrochemical sensor: {Mo368} as electrode donor for Bi2S3 and Au co-sensitized FeOOH composite

A Lanthanide-Incorporated Phospho(III)tungstate Aggregate Constructed from [HPIIIW8O31]10- and [W11O39]12- Building Blocks and Its Nanocomposite with CdS for Ultrasensitive Photoelectrochemical Detection of Oxytetracycline

A novel tartronic acid decorated hexa-CeIII-incorporated phospho(III)tungstate aggregate (C4H12NO)6Na18H2[(HPW8O31)2[W11O39]2(H2TAD)4(H2O)4W4Ce6H2P2O14]·84H2O (1, H3TAD = tartronic acid) was synthesized by a one-step assembly strategy. Its main skeleton is constructed from two [W11O39]12- fragments, two [HPIIIW8O31]10- segments and one H2TAD--ornamented dodecanuclear heterometallic [W4Ce6H2PIII2O14(H2TAD)4(H2O)4]18+ cluster. In the structure, the [HPIIIO3]2- groups not only work as the heteroatom template to induce the formation of lacunary [HPIIIW8O31]10- segments but also function as the connector to bridge Ce3+ cations. With the help of a reaction strategy of combining ultrasonication treatment with the continuous ion layer adsorption method, the 1/CdS composite was constructed and exhibits prominent photoelectrochemical activity. The 1/CdS composite was used as a photoelectrochemical sensor for oxytetracycline detection at 0 V (vs Ag/AgCl), which displays excellent properties with quick response and low limit of detection (0.042 nM). This work can provide some helpful references in the construction of novel PIII-induced polyoxometalates consisting of different building blocks and can extend the applications of polyoxometalate-based nanocomposites into photoelectrochemical detection for antibiotics as well as biomolecules.

Huge Electron Sponge of Polyoxometalate toward Advanced Lithium-Ion Storage

The huge polyoxometalate, N a 48 [ H x M o 256 V I M o 112 V O 1032 ( H 2 O ) 240 ( SO 4 ) 48 ] ({Mo368}), which can be prepared by a facile solution process and can be applied in lithium-ion storage applications as the anode. The large and open hollow nanostructure is promising to store a larger number of lithium ions and expedite the diffusion of lithium ions. A single {Mo368} nanocluster can transfer 624 electrons, referred to as a "huge electron sponge". Pure {Mo368} without any support materials exhibits very high capacities of 964 mA h g-1 with hardly any decay for 100 cycles at 0.1 A g-1 and still maintains 761 mA h g-1 after 180 cycles at 0.5 A g-1, indicating great cycling stability. The {Mo368} anode provides excellent rate performance and reversibility during the lithiation/delithiation processes, which are contributed by both the diffusion-controlled process and the capacitive process. The capacitive contribution can reach 71.7% at a scan rate of 2 mV s-1. The high DLi+ value measured by GITT confirms the fast reaction kinetics of the {Mo368} electrode. The {Mo368}//NCM111-A full cell is practically applied to light LED lamps. These investigations indicate that {Mo368} nanoclusters are advanced energy storage materials with high capacities, fast charge transfer, and low-cost mass production for lithium-ion storage. Moreover, {Mo368} should be considered a clean energy material because there is no production of environmental pollution during the charge/discharge processes.

Self-powered photochemical cathode aptamer sensor based on ZnIn2S4 photoanode and Cu2O@Ag@Ag3PO4 photocathode for the sensitive detection of Hg2

A self-powered photoelectrochemical (PEC) aptamer sensor based on ZnIn2S4 as the photoanode and Cu2O@Ag@Ag3PO4 as the sensing cathode is designed for the detection of Hg2+. An indium tin oxide (ITO) electrode modified with ZnIn2S4 was used instead of a platinum (Pt) counter electrode to provide an obviously stable photocurrent signal. The suitable band gap width of ZnIn2S4 can generate photogenerated electrons well. The unique hydrangea structure of ZnIn2S4 can enhance light absorption and accelerate the separation and transfer of photocarriers. At the same time, Cu2O@Ag@Ag3PO4 with excellent electrical conductivity further enhances the photocurrent provided by the ZnIn2S4 photoanode. Because the reducing substances in the biological medium can change the photoanode characteristics of the photoanode interface, the separation of the photoanode and the sensing bicathode is beneficial to improve the anti-interference ability of the sensor. Under optimized conditions, the PEC aptamer sensor realizes the detection of Hg2+ (1 mM-1 fM), and the detection limit is 0.4 fM. In addition, the constructed self-powered PEC sensor has good selectivity, repeatability, and stability, which provides a new idea for the design of the PEC aptamer sensor platform.

Insights into the self-assembly of giant polyoxomolybdates from building blocks to supramolecular structures

Giant polyoxomolybdates are a special class of polyoxometalate clusters which can bridge the gap between small molecule clusters and large polymeric entities. Besides, giant polyoxomolybdates also show interesting applications in catalysis, biochemistry, photovoltaic and electronic devices, and other fields. Revealing the evolution route of the reducing species into the final cluster structure and also their further hierarchical self-assembly behaviour is undoubtedly fascinating, aiming to guide the design and synthesis. Herein, we reviewed the self-assembly mechanism study of giant polyoxomolybdate clusters, and the exploration of a new structure and new synthesis methodology is also summarized. Finally, we emphasize the importance of in-operando characterization in revealing the self-assembly mechanism of giant polyoxomolybdates, and especially for the further reconstruction of intermediates into the designable synthesis of new structures.

Pt Nanodot Inlaid Mesoporous NaBiOF Nanoblackberry for Remarkable Signal Amplification Toward Biomarker Detection

A new ultrasensitive sandwich-type electrochemical immunosensor has been successfully constructed to quantitatively detect carcinoembryonic antigen (CEA) using blackberry-like mesoporous bismuth-based nanospheres NaBiOF (NBOF NSs) inlaid with Pt nanodots (NDs) (BiPt NSs) as the antibody capture and signal-amplifying probe. The growth of Pt NDs inside the holes of NBOF NSs formed the nanozyme inlay outside NBOF NSs, greatly increasing the specific surface area and exposure of the catalytic active sites by minimizing the particle size of the Pt to nanodot scale. Such a blackberry-shaped heterojunction structure of BiPt NSs was well-suited to antibody capture and improved the catalytic performance of BiPt NSs in reducing H₂O₂, amplifying the signal, and yielding highly sensitive detection of CEA. The use of Au nanoparticle-modified multi-walled carbon nanotubes (Au@MWCNTs) as the electrode substrates significantly enhanced the electron transfer behavior over the electrode surface, further increasing the conductivity and sensitivity of the immunosensor. Remarkably, good compatibility with human body fluid was achieved using the newly developed BiPt-based immunosensor resulting from the favorable biocompatibility and stability of both BiPt NSs and Au@MWCNTs. Benefiting from the double signal amplification strategy and the high biocompatibility, the immunosensor responded linearly to CEA in a wide range from 50 fg/mL to 100 ng/ml with an extremely low detection limit of 3.52 fg/mL (S/N = 3). The excellent detection properties of this new immunosensor were evidenced by the satisfactory selectivity, reproducibility, and stability obtained, as well as the reliable and precise determination  of CEA in actual human blood samples. This work provides a new strategy for the early clinical diagnosis of cancer. Novel blackberry-like mesoporous NaBiOF nanospheres with Pt nanodot inlay were successfully usedto construct a sandwich-type electrochemical immunosensor for the ultra-sensitive detection ofcarcinoembryonic antigen in human blood plasma based on a remarkable signal amplification strategy.

A novel construction strategy of photoelectrochemical immunosensor for detecting neuron-specific enolase: Sensing mode integrating photoanode and photocathode

In the realm of photoelectrochemical (PEC) analysis, it is customary to employ a lone photoanode or photocathode system for analyte detection. Nonetheless, such a single detection scheme inherently carries some deficiencies. While photoanode-based PEC immunoassay methods do exhibit conspicuous photocurrent responses and heightened sensitivity, they do suffer from inadequate resistance to interference when detecting in real sample detection. Photocathode-based analysis methods are capable of effectively surmounting the limitations of photoanode-based analysis methods, but their stability is poor. Based on the above reasons, this paper reports a novel immunosensing system combining ITO/WO₃/Bi₂S₃ photoanode and ITO/CuInS₂ photocathode. The system that incorporates both photoanode and photocathode exhibits a steady and discernible photocurrent, possesses robust resistance to external interference, and has effectively accomplished the quantification of NSE in the linear range from 5 pg/mL to 30 ng/mL. Remarkably, the detection limit has been determined to be 1.59 pg/mL. Besides the notable advantages of satisfactory stability, exceptional specificity, and outstanding reproducibility, the sensing system also introduces an innovative approach to fabricate PEC immunosensors.

Polyoxometalate Functionalized Sensors: A Review

Polyoxometalates (POMs) are a class of metal oxide complexes with a large structural diversity. Effective control of the final chemical and physical properties of POMs could be provided by fine-tuning chemical modifications, such as the inclusion of other metals or non-metal ions. In addition, the nature and type of the counterion can also impact POM properties, like solubility. Besides, POMs may combine with carbon materials as graphene oxide, reduced graphene oxide or carbon nanotubes to enhance electronic conductivity, with noble metal nanoparticles to increase catalytic and functional sites, be introduced into metal-organic frameworks to increase surface area and expose more active sites, and embedded into conducting polymers. The possibility to design POMs to match properties adequate for specific sensing applications turns them into highly desirable chemicals for sensor sensitive layers. This review intends to provide an overview of POM structures used in sensors (electrochemical, optical, and piezoelectric), highlighting their main functional features. Furthermore, this review aims to summarize the reported applications of POMs in sensors for detecting and determining analytes in different matrices, many of them with biochemical and clinical relevance, along with analytical figures of merit and main virtues and problems of such devices. Special emphasis is given to the stability of POMs sensitive layers, detection limits, selectivity, the pH working range and throughput.

Enhancement of photocurrent by incorporation of Preyssler type polyoxometalate protected nanoparticles in polyporphyrin films

The introduction of nanoparticles (MNPs) at the surface of cationic poly-porphyrin films, obtained by electrostatic interaction between the bis-porphyrin copolymer and the Preyssler type polyoxometalate P5W30@MNPs, enhances the photocurrent (up to 2.5-3 times greater as a function of the used nanoparticle).

The trends in nanomaterial-based biosensors for detecting critical biomarkers in stroke

Acute ischemic stroke (AIS), is the second global cause of death after cardiovascular diseases, accounts for 80-85% of cerebrovascular disease. Stroke diagnosis could be challenging in the acute phase. Detection of biomarkers for evaluating the prognosis of diseases is essential for improving personalized treatment and decreasing mortality. At the present time, the absence of a broadly existing and rapid diagnostic test is an important limitation in the evaluation and treatment of diseases. The use of a biomarker-based diagnostic attitude has confirmed very valuable in acute coronary syndromes, which has been promoted in acute stroke to help early management decisions. Over the past decade, different detection procedures have developed for the assessment of human cardiac troponins (cTnI). This review emphasizes on summarizing optical, and electrochemical biosensors for the detection of cTnI, brain natriuretic peptide (BNP), and neuron-specific enolase (NSE) as a critical biomarker in stroke.