Elsevier最新文献

Directly detecting biomarkers in liquid biopsy for diagnosis and personalized treatment plays a crucial role in managing cancer relapse and increasing survival rates. Typically, the standard analysis of circulating tumour DNA requires lengthy isolation, extraction, and amplification steps, leading to sample contamination, longer turnaround time and higher assay costs. Surface plasmon resonance is an emerging and promising technology for rapid and real-time dynamic biomarker monitoring in liquid biopsy. Here, we propose a new SPR imaging biosensing approach to detect tumour DNA circulating in the blood of colorectal cancer patients by exploiting the unique properties of superparamagnetic particles. Micrometer beads functionalized with a biotinylated oligonucleotide can directly capture DNA target sequences bearing single-nucleotide variations of KRAS oncogene in human blood plasma. Mutated and wild-type peptide nucleic acid probes immobilized on an SPR gold surface recognize complementary and non-complementary DNA targets by discriminating a single nucleotide mismatch. The new assay allows for detecting p.G13D mutated DNA in buffer and spiked human plasma at attomolar level (down to 300 copies mL^-1) with minimal sample manipulation and in just a few microliters. The assay was validated using plasma samples from colorectal cancer patients and healthy donors, by discriminating mutated DNA circulating in patients and wild-type DNA found in healthy blood donors. This feature underscores the potential of the liquid biopsy assay as a valuable tool for the diagnosis and monitoring of cancer.

Cancer Antigen 125 (CA125), is a high molecular weight mucinous glycoprotein found on the surface of ovarian cancer cells. Generally, 90 % of women may appear a high concentration of CA125 when they got the cancer; thus, CA125 can act as a marker for ovarian cancer diagnosis and therapeutic evaluation. COFs have been widely used for disease detection due to their structural stability, high loading capacity and biocompatibility. However, the limited variety of electroactive COFs used as signal probes, fewer enriched signaling molecules, weaker electrical signals generated, and higher oxidation or reduction potentials of electroactive substances, a series of side reactions are easily triggered causing serious interference. To solve the above problems, [Fe(CN)6]^3/4- as a signal probe and COFs for signal amplification were selected to creating a highly sensitive electrochemical immunosensor for glycan antigen CA125. Firstly, two-dimensional (2D) EP-TD-COF with ultra-high specific surface area was modified on bare GCE, which could covalently bound numerous Ab1 molecules due to the epoxy-rich functional groups. Then, the electropositive AuNPs@2DCOFBTT-DGMH was prepared by the in situ growth of AuNPs, proved an effective platform for loading Ab2 molecules via Au-S bonds. Based on the positively charged AuNPs@COFBTT-DGMH/Ab2 and negatively charged [Fe(CN)6]^3/4- of electrostatic interactions, which could significantly enchaned signal for quantitative and sensitive detection of CA125. The constructed immunosensor exhibits excellent stability performance and high sensitivity, enabling ultrasensitive detection of trace glycan antigens. This study provided a new idea for the use of non-electroactive substances for the construction of electrochemical immunosensors and provided an effective signal amplification strategy.

Measuring the radioactivity of organically bound tritium in environmental samples is difficult. For the past twenty years, many laboratories have been working on the development of reliable tritium measurement methods. In this context, several interlaboratory comparisons have been organised to develop these methods and enable laboratories to compare themselves. However, the trueness of the measurement methods has never been estimated due to the lack of certified reference materials available for use during the analyses. This document presents the production of the first certified reference material for the measurement of organically bound tritium radioactivity in environmental samples.

The low sensitivity of Lateral flow assay (LFA) limits its application in rapid detection for trace targets. LFAs with nanozyme (nanozyme-LFA) as signal labels have demonstrated excellent performance in point of care testing (POCT). However, additional operational steps for substrate catalysis in nanozyme LFA are required, which makes the nanozyme-LFA operation complicated. In this work, we designed a LFA based on delayed substrate release (SGF-LFA), in which a commercialized glass fiber membrane embedded with substrate (SGF) was fixed at the sample pad. The SGF could automatically execute substrate delivery and catalysis, thus eventually achieving a one-step LFA operation for the nucleic acid detection of influenza A virus H1N1. In this SGF-LFA, 3,3 '- diaminobenzidine (DAB) was oxidized and deposited, producing a strong signal amplification under the catalysis of Au@PtNP nanozyme. The SGF-LFA could detect the nucleic acid of H1N1, with a linear range of 0.02-50 nM and a limit of detection (LOD) as low as 0.02 nM, which was 25-fold lower than that of the nanozyme-LFA before catalysis. In addition, the analytical performance was close to that of a manual operation mode of catalysis amplification. The application of SGF-LFA for detecting the H1N1 nucleic acid in serum samples obtained a recovery rate of 96 %-102.7 %, indicating that SGF-LFA has great potential in point-of-care testing.

Anthropogenic activities have led to increased stress on our marine and other aquatic environments. There is a pressing need to monitor, measure, understand and mitigate causes of these pressures. This paper presents a novel optical head for monitoring and measuring marine based optical phenomena. The development and preliminary testing of the optical head were designed to detect optically active constituents in the marine and coastal environments. Potential applications may include the detection of Harmful Algal Blooms (HAB), which due to their production of toxins have deleterious effects on marine ecosystems, dissolved organic matter (DOM), oil spills, through the measurement of dissolved fluorescent petroleum compounds and turbidity, a key metric in marine and water quality measurements. Preliminary laboratory based results indicate that the optical head is well suited for measuring in-vivo Chlorophyll a (Chl a) fluorescence, turbidity, fluorescent dissolved organic matter (fDOM) and petroleum. For turbidity and in-vivo Chl a, analytical performance was benchmarked against off-the-shelf commercial sensors. The developed optical head demonstrates good analytical performance with certified reference standards and a very good agreement with the reference instrument.

A novel strategy for cytochrome c selective recognition assisted with cucurbit[6]uril by host-guest interaction via N-terminal epitope imprinting and reversible addition-fragmentation chain transfer (RAFT) polymerization was developed. N-terminal nonapeptide of cytochrome c (GI-9) was used as the epitope template to achieve highly selective recognition of cytochrome c. As a common supramolecule in recent years, cucurbit[6]uril can encapsulate the butyrammonium group of lysine residue to capture the peptide and improve the corresponding spatial orientation by the host-guest interaction for GI-9 or cytochrome c recognition. After cucurbit[6]uril modification and epitope immobilization, the imprinted polymer was synthesized by RAFT polymerization with 2-dodecylsulfanylcarbothioylsulfanyl-2-methylpropanoic acid as chain transfer agent. After template removal, the obtained imprinted particles showed good binding ability to GI-9 (20.28 mg g^-1, IF = 4.11) and cytochrome c (36.12 mg g^-1, IF = 3.91). With the successive addition of cucurbit[6]uril and RAFT agent, the step-by-step improvement of the IF for cytochrome c recognition further illustrated the effects of supramolecular host-guest interaction and regulation of imprinted polymer chain. The imprinted polymers showed obvious advantages for cytochrome c recognition compared to competitive proteins and had good reusability with the repeated reproduction rate 80.8 % after five cycles of adsorption and desorption. Furthermore, the selective recognition for cytochrome c in adult bovine serum proved its potentiality to be applied in practical samples. All these results demonstrated that the combination of epitope imprinting, cucurbit[6]uril host-guest interaction and RAFT strategy presented an efficient new feasible control method for protein recognition with good selectivity, stability and reusability.

Formaldehyde (HCHO) is a harmful volatile organic pollutant, which is commonly found in interior decoration and furniture products. Therefore, it is necessary to develop a gas sensor that can quickly and accurately detect formaldehyde for human health and environmental protection. In order to achieve this goal, in this work, SnS₂/SnO₂ heterostructure was synthesized by in-situ sulfurization process on the basis of SnO₂ nanospheres, and its formaldehyde sensing performance was studied. After testing, it was found that the gas sensor based on SnS₂/SnO₂ heterojunction has more excellent gas sensing performance than pure SnO₂ gas sensor at the same operating temperature (100 °C). Specifically, SnS₂/SnO₂-2 (Sn:S = 3:2) has the advantages of high sensitivity (4.01 at 0.1 ppm), excellent selectivity, low theoretical detection limit (13.26 ppb), good humidity resistance and long-term stability. The excellent sensing performance of SnS₂/SnO₂ sensors for formaldehyde detection is mainly attributed to the n-n heterojunction formed by SnS₂ and SnO₂, which generates a built-in electric field to accelerate the electron transport in the material, the higher oxygen vacancy sites adsorb a large number of reactive gas molecules to promote the oxidation of formaldehyde molecules, and the unique porous structure to promote the transmission and diffusion of gases and increase the surface area to provide more adsorption sites and reactive centers for gas molecules. Therefore, the construction of SnS₂/SnO₂ heterostructures will be an effective way to develop next-generation formaldehyde gas sensors with higher sensing performance.

Glucose detection is crucial for diagnosis, prevention and treatment of diabetes mellitus. In this work, 10 nm Al₂O₃ thin film was introduced on the channel of diamond solution-gate field-effect transistor (SGFET) to improve the performance of glucose detection. AFM results show the roughness of channel surface increased after Al₂O₃ thin film deposition. Then, 1-pyrenebutyric acid-N-hydroxy succinimide ester (Pyr-NHS) and glucose oxidase (GOD) were linked on the channel. The morphology after each modification step was evaluated by SEM, and the result indicated an uneven Al₂O₃ distribution. XPS spectra further confirmed the effective modification of Pyr-NHS and GOD. In addition, the shifts of transfer characteristics for each concentration of glucose were analyzed, which illustrated a wide linear response (10^-8-10^-2 M), a high sensitivity (-44.01 mV/log₁₀[glucose concentration]) and a low detection limitation (10^-8 M). All these results show an excellent detection performance, which may provide a new idea for the design of diamond SGFET biosensor.

Searching for new alternative to tripropylamine (TPrA) with low toxicity and high chemical stability for the tris(4,4'-dicarboxylic acid-2,2'-bipyridyl)ruthenium (II) (Ru(dcbpy)₃²⁺) based coreactant electrochemiluminescence (ECL) system is essential for widespread analytical applications. Here, nitrogen-doped graphene quantum dots (NGQDs) have been discovered to significantly amplify the ECL emission and increase the ECL efficiency of Ru(dcbpy)₃²⁺ for the first time. However, the mechanism by which NGQDs act as coreactants is not well comprehended. Therefore, various optical and electrochemical technologies were employed to investigate the ECL mechanism. It is proposed that the amino and carboxyl groups on the surface of NGQDs play crucial roles as the coreactant active sites, catalyzing the oxidation of Ru(dcbpy)₃²⁺. Based on this foundation, an "on-off-on" ECL aptasensor for the quantification of acetamiprid was developed, exhibiting a broad linear range and a detection limit of 0.056 pM. Satisfactory recoveries, ranging from 98.0 % to 101.6 %, were achieved in pakchoi samples. Consequently, NGQDs could serve as coreactants for Ru(dcbpy)₃²⁺, offering new opportunities for constructing a variety of sensors with extensive analytical applications in the ECL field.

Photocatalytic reduction of CO₂ to valuable chemicals is an effective strategy to address the environmental problems and energy crisis. Covalent organic frameworks (COFs) are emerging materials known for their excellent diverse properties, albeit limited by special synthetic methods, including high temperature (120 °C) and the necessity of inert gas atmosphere. Herein, a novel synthesis method under room temperature and air was optimized to form TpPa-COF (TP-COF) by p-phenylenediamine (Pa) and 2,4,6-triformyl phloroglucinol (Tp) through electrostatic self-assembly. To further expand the application scope of TP-COF, a heterojunction structure was constructed by in-situ growth of TP-COF onto TiO₂ to form TiO₂@TP-COF. In the photocatalytic CO₂ reaction of TiO₂@TP-COF composites, TiO₂ acts as a reduction site to reduce CO₂ to CO, and triethanolamine (TEOA) acts as a hole-sacrificing reagent. It was demonstrated by in situ X-ray photoelectron spectroscopy (XPS) that the direction of electron transfer in the TiO₂@TP-COF composites flowed from TP-COF to TiO₂. Meanwhile, TEOA on TP-COF was oxidized to consume holes and produce protons for the reduction of CO₂. Combining the advantages of organic and inorganic semiconductors, the heterojunction structure effectively improves the photocatalytic properties of TiO₂@TP-COF under visible light irradiation. TiO₂@TP-COF demonstrates a remarkable photocatalytic CO₂ reduction rate of 133.37 μmol/g/h at λ = 420 nm, which is 3.19 and 2.88 times higher than that of TP-COF and TiO₂, respectively, while exhibiting a selectivity of 73 % for CO. This convenient method of synthesizing TiO₂@TP-COF catalysts will open up new perspectives for future COF-based materials.