Developing highly sensitive multiplex immunoassays is urgently needed to guide medical research and improve clinical diagnosis. Here, we report the proximity electrochemiluminescence (ECL) generation enabled by gold microbeads (GMBs) for improving the detection sensitivity and multiplexing capacity of ECL immunoassays (ECLIAs). As demonstrated by microscopy and finite element simulation, GMBs can function as spherical ultramicroelectrodes for triggering ECL reactions in solutions. Employing GMBs as solid carriers in the bead-based ECLIA, the electrochemical oxidation of a coreactant can occur at both the GMB surface and the substrate electrode, allowing the coreactant radicals to diffuse only a short distance of ∼100 nm to react with ECL luminophores that are labeled on the GMB surface. The ECL generation via this proximity low oxidation potential (LOP) route results in a 21.7-fold increase in the turnover frequency of ECL generation compared with the non-conductive microbeads that rely exclusively on the conventional LOP route. Moreover, the proximity ECL generation is not restricted by the diffusion distance of short-lived coreactant radicals, which enables the simultaneous determination of multiple acute myocardial infarction biomarkers using size-encoded GMB-based multiplex ECLIAs. This work brings new insight into the understanding of ECL mechanisms and may advance the practical use of multiplex ECLIAs.
In addition to repressing proliferation, inhibiting the infiltration of tumor cells is an important strategy to improve the treatment of malignant tumors. Herein, a photocatalyst (pCNMC@Pt) is designed by sequentially assembling manganese dioxide, chlorin e6, and platinum (Pt) nanoparticles onto protonated graphitic carbon nitride. With the help of a Z-scheme structure and near-infrared (NIR) photosensitizer, pCNMC@Pt is capable of responding to NIR light to generate large amounts of hydrogen (H
Metasedimentary rock-hosted stratiform Cu-Co (MSC) deposits are one of the important types of Co deposits. Previous research has primarily concentrated on Cu mineralization. However, the occurrence, source, and enrichment mechanism of Co are still poorly understood. Here, we conducted an LA-ICP-MS trace elemental analysis of the pyrrhotite, chalcopyrite, and sphalerite from the Heiniudong MSC deposit, the largest one in western Sichuan, China. The results indicate that Co in Heiniudong primarily exists as an isomorphic substitution in pyrrhotite (393–1222 ppm) and sphalerite (162–393 ppm), with a small amount occurring in the form of costibite. Cu and Co in the Heiniudong deposit are highly likely homologous, and both probably originated from the metabasites of the Liwu Group. At different stages, sphalerite exhibits enrichment of elements such as Fe (58157–75386 ppm), Mn (781–2861 ppm), and In (855–1862 ppm), indicating a high temperature throughout the whole mineralization process. In combination with previous studies, our data indicate that Co and other metals were introduced into the metallogenic system early on and subsequently underwent multiple periods of superimposed transformation and enrichment, ultimately forming industrial orebodies. In addition, the lower salinity of the ore-forming fluids may be one of the reasons why the Co grades of the Heiniudong and other MSC deposits are usually lower than those of SSC deposits.
Past research on the process of extinguishing a fire typically used a traditional linear water jet falling point model and the results ignored external factors, such as environmental conditions and the status of the fire engine, even though the water jet falling point location prediction was often associated with these parameters and showed a nonlinear relationship. This paper constructed a BP (Back Propagation) neural network model. The fire gun nozzle characteristics were included as model inputs, and the water discharge point coordinates were the model outputs; thus, the model could precisely predict the water discharge point with small error and high precision to determine an accurate firing position and allow for the timely adjustment of the spray gun. To improve the slow convergence and local optimality problems of the BP neural network (BPNN), this paper further used a genetic algorithm to optimize the BPNN (GA-BPNN). The BPNN can be used to optimize the weights in the network to train them for global optimization. A genetic algorithm was introduced into the neural network approach, and the water jet landing prediction model was further improved. The simulation results showed that the prediction accuracy of the GA-BP model was better than that of the BPNN alone. The established model can accurately predict the location of the water jet, making the prediction results more useful for firefighters.
Abstract The direct electron transfer and electrocatalysis of horseradish peroxidase (HRP) immobilized on hexagonal mesoporous silicas (HMS) matrix was studied. The interaction between HRP and HMS was examined by using Fourier transform infrared spectroscopy, nitrogen adsorption isotherms and electrochemical methods. The immobilized HRP at a modified glassy carbon electrode showed a good direct electrochemical behavior, which depended on the specific properties of the HMS. Two couples of redox peaks corresponding to Fe(III) to Fe(II) conversion of the HRP intercalated in the mesopores and adsorbed on the external surface of the HMS were observed with the formal potentials of −0.315 and −0.161 V in 0.1 M pH 7.0 PBS, respectively. The amount of HRP intercalated in the mesopores of HMS proved to be related to the pore size. The HRP intercalated in the mesopores showed a surface controlled electrode process with a single proton transfer. The immobilized HRP displayed an excellent electrocatalytic response to the reduction of hydrogen peroxide (H 2 O 2 ) without the aid of an electron mediator. The HMS provided a novel matrix for protein immobilization and direct electron transfer study of the immobilized protein.
Carrier generation and migration are both pivotal to photoelectric (PE) response. Formation of a Schottky contact is conducive to promote carrier migration but cannot fundamentally magnify carrier generation, limiting the eventual PE performance. In this work, an Au@Ag/AgI Schottky contact is established by in situ growth of AgI nanotriangles on the surface of Au@Ag nanoparticles (NPs), and PE enhancement of the Schottky contact is realized by regulating localized surface plasmon resonance (LSPR) properties. In comparison with Ag/AgI Schottky contact, assembly of Au NPs in the center of Ag NPs adjusts the dominated LSPR property from hot-electron transfer (HET) to plasmon-induced resonance energy transfer (PIRET). With the concurrent manipulation of HET and PIRET, additional energy can be employed for carrier generation, while photogenerated electrons offset by hot electrons are reduced, which jointly enlarges PE responses of the Au@Ag/AgI Schottky contact up to 4 times. Benefitted from the etching of thiols to Ag-based materials, the Au@Ag/AgI Schottky contact is further applied to the construction of a photoelectrochemical cysteine sensor. This work proposes a general strategy to enhance PE responses of Schottky contacts, which may advance the design of LSPR-related PE systems.
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