Dual-microRNA-Controlled Electrochemiluminescence Biosensor for Breast Cancer Diagnosis and Supplemental Identification of Breast Cancer Metastasis.

Breast cancer remains the most frequently diagnosed cancer globally, and the metastasis of this malignancy is the primary cause of mortality in breast cancer patients. Hence, prompt diagnosis and timely detection of metastatic breast cancer are critical for effective therapeutic intervention. Both progression and metastasis of this malignancy are closely associated with aberrant expression of specific microRNAs (miRNAs) and enzymes. To facilitate breast cancer diagnosis and concomitant identification of metastatic breast cancer, we have engineered an innovative electrochemiluminescence (ECL)-based sensing platform integrated with enzyme-free DNA amplification circuits for dual functionality. Specifically, microRNA-21 (miR-21) is employed as a biomarker for breast cancer, and miR-21 induces the quenching of the ECL signal from luminophores via a strategically designed catalytic three-hairpin assembly (CTHA) circuit. Subsequently, miR-105 levels are measured via toehold-mediated strand displacement reactions (TSDR). Here, miR-105 restores the initially quenched ECL signal, enabling the assessment of the metastatic propensity. Our experimental data demonstrate that the devised ECL biosensor offers broad linear detection ranges and low detection limits for both miR-21 and miR-105. Importantly, our novel platform was also successfully validated by using cellular and serum samples. This biosensor not only discriminates breast cancer cell lines MCF-7 and MDA-MB-231 from nonbreast cancer cells like HepG2, TPC-1, and HeLa, but it also distinguishes between malignant MCF-7 and metastatic MDA-MB-231 cells. Consequently, our novel approach holds significant promise for clinical applications and precise cancer screening.

A Dual-Mode Fluorescent Nanoprobe for the Detection and Visual Screening of Pathogenic Bacterial Spores.

Bacterial vegetative cells turn into metabolically dormant spores in certain environmental situations. Once suitable conditions trigger the germination of spores belonging to the pathogenic bacterial category, public safety and environmental hygiene will be threatened, and lives will even be endangered when encountering fatal ones. Instant identification of pathogenic bacterial spores remains a challenging task, since most current approaches belonging to complicated biological methods unsuitable for onsite sensing or emerging alternative chemical techniques are still inseparable from professional instruments. Here we developed a polychromatic fluorescent nanoprobe for ratiometric detection and visual inspection of the pathogenic bacterial spore biomarker, dipicolinic acid (DPA), realizing rapidly accurate screening of pathogenic bacterial spores such as Bacillus anthracis spores. The nanoprobe is made of aminoclay-coated silicon nanoparticles and functionalized with europium ions, exhibiting selective and sensitive response toward DPA and Bacillus subtilis spores (simulants for Bacillus anthracis spores) with excellent linearity. The proposed sensing strategy allowing spore determination of as few as 0.3 × 105 CFU/mL within 10 s was further applied to real environmental sample detection with good accuracy and reliability. Visual quantitative determination can be achieved by analyzing the RGB values of the corresponding test solution color via a color recognition APP on a smartphone. Different test samples can be photographed at the same time, hence the efficient accomplishment of examining bulk samples within minutes. Potentially employed in various on-site sensing occasions, this strategy may develop into a powerful means for distinguishing hazardous pathogens to facilitate timely and proper actions of dealing with multifarious security issues.

A Pyroglutamate Aminopeptidase 1 Responsive Fluorescence Imaging Probe for Real-Time Rapid Differentiation between Thyroiditis and Thyroid Cancer.

Current diagnostic methods for thyroid diseases, including blood tests, ultrasound, and biopsy, always have difficulty diagnosing thyroiditis accurately, occasionally mistaking it for thyroid cancer. To address this clinical challenge, we developed Ox-PGP1, a novel fluorescent probe realizing rapid, noninvasive, and real-time diagnostic techniques. This is the first imaging tool capable of noninvasively distinguishing between thyroiditis and thyroid cancer. Ox-PGP1 was introduced as a fluorescent probe custom-built for the specific detection and quantification of pyroglutamate aminopeptidase 1 (PGP-1), a known pivotal biomarker of inflammation. Ox-PGP1 overcame the disadvantages of traditional enzyme-responsive fluorescent probes that relied on the intramolecular charge transfer (ICT) mechanism, including the issue of high background fluorescence, while offering exceptional photostability under laser irradiation. The spectral properties of Ox-PGP1 were meticulously optimized to enhance its biocompatibility. Furthermore, the low limit of detection (LOD) of Ox-PGP1 was determined to be 0.09 µg/mL, which demonstrated its remarkable sensitivity and precision. Both cellular and in vivo experiments validated the capacity of Ox-PGP1 for accurate differentiation between normal, inflammatory, and cancerous thyroid cells. Furthermore, Ox-PGP1 showed the potential to rapidly and sensitively differentiate between autoimmune thyroiditis and anaplastic thyroid carcinoma in a mouse model, achieving results in just 5 min. The successful design and application of Ox-PGP1 represent a substantial advancement in technology over traditional diagnostic approaches, potentially enabling earlier interventions for thyroid diseases.

Dual-Signal Triple-Mode Optical Sensing Platform for Assisting in the Diagnosis of Kidney Disorders.

As known biomarkers of kidney diseases, N-acetyl-ß-d-glucosaminidase (NAG) and ß-galactosidase (ß-GAL) are of great importance for the diagnosis and treatment of diseases. The feasibility of using multiplex sensing methods to simultaneously report the outcome of the two enzymes in the same sample is even more alluring. Herein, we establish a simple sensing platform for the concurrent detection of NAG and ß-GAL using silicon nanoparticles (SiNPs) as a fluorescent indicator synthesized by a one-pot hydrothermal route. p-Nitrophenol (PNP), as a common enzymatic hydrolysis product of the two enzymes, led to the attenuation of fluorometric signal caused by the inner filter effect on SiNPs, the enhancement of colorimetric signal due to the increase of intensity of the characteristic absorption peak at around 400 nm with increasing reaction time, and the changes of RGB values of images obtained through a color recognition application on a smartphone. The fluorometric/colorimetric approach combined with the smartphone-assisted RGB mode was able to detect NAG and ß-GAL with good linear response. Applying this optical sensing platform to clinical urine samples, we found that the two indicators in healthy individuals and patients (glomerulonephritis) with kidney diseases were significantly different. By expanding to other renal lesion-related specimens, this tool may show great potentials in clinical diagnosis and visual inspection.

Leucine Aminopeptidase-Mediated Multifunctional Molecular Imaging Tool for Diagnosis, Drug Evaluation, and Surgical Guidance of Liver-Related Diseases.

Traditional molecular imaging tools used for detecting liver diseases own several drawbacks, such as poor optical performance and limited applicability. Monitoring the concentration of leucine aminopeptidase (LAP), which is closely related to liver diseases such as liver cancer and liver injury, and analyzing it in diagnosis, drug evaluation, and surgical treatment is still a challenging task. Herein, we construct an intramolecular charge-transfer mechanism-based, ultrasensitive, near-infrared fluorescent probe (LAN-lap) for dynamic monitoring of LAP fluctuations in living systems. LAN-lap, with high specificity, stability, sensitivity, and water solubility, can achieve in vitro monitoring of LAP through both fluorescence and colorimetric methods. Moreover, LAN-lap can successfully be used for the localization imaging of endogenous LAP, confirming the upregulation of LAP expression in liver cancer and liver injury cells. In addition, LAN-lap can realize the imaging of liver tumors in living organisms. Meanwhile, it can intuitively present the degree of drug-induced liver injury, achieving semi-quantitative imaging evaluation of the hepatotoxicity of two drugs. Furthermore, LAN-lap can track liver cancer tumors in mice with peritoneal metastasis and can assist in fluorescence-guided surgical resection of liver cancer tumors. This multifunctional LAN-lap probe could play an important role in facilitating simultaneous diagnoses, imaging, and synergistic surgical navigation to achieve better point-of-care therapeutic efficacy.

A Strategy for the Determination of Alkaline Phosphatase Based on the Self-Triggered Degradation of Metal-Organic Frameworks by Phosphate.

Alkaline phosphatase (ALP) is widely present in the human body and is an important biomarker. Numerous ALP detection studies have been carried out, and ascorbic acid (AA) is often used as the reducing component in the sensors to monitor ALP levels since it can be produced from ascorbic acid 2-phosphate (AA2P) hydrolysis in the presence of ALP. However, it is well-known that AA is a strong reducing agent and can be easily oxidized. The disproportion between oxidized AA and reduced AA reactions results in the generation of AA free radicals with single electrons that may lead to inaccurate results in assays. To solve this problem, we synthesized a core-shell metal-organic framework sensor (PATP-Au@ZIF-8 NP) and used it as a sensitive and accurate ALP detection sensor with self-triggered control of phosphate ions (Pi) to avoid the potential inaccuracy of the method that uses AA as the reducing component. By establishing a physical shell on the surface of the gold nanoparticles (Au NPs), the sensor not only can eliminate the random assembly of metal nanoparticles caused by plasma exposure but also can generate self-triggering of Pi caused by ALP. Pi can decompose ZIF-8 through coordination with Zn2+ and thus can destroy the ZIF-8 shell structure of the prepared PAZ NPs. Au NPs are released and then become aggregated, in turn causing the SERS "hot spot" area to increase. The enhancement of the SERS signals was found to be directly associated with the level of Pi released from ALP-triggered hydrolysis. The response of the strategy was linear at ALP concentrations ranging from 0.1 to 150 mU/mL (r = 0.996) with a detection limit of 0.03 mU/mL. Lastly, the developed strategy was employed in the evaluation of ALP inhibitors, and the possibility to implement the developed SERS strategy for rapid and selective analysis of ALP in human serum was demonstrated.

Chemosensor with Ultra-High Fluorescence Enhancement for Assisting in Diagnosis and Resection of Ovarian Cancer.

Fluorescence imaging-guided diagnostics is one of the most promising approaches for facile detection of tumors in situ owing to its simple operation and non-invasiveness. As a crucial biomarker for primary ovarian cancers, ß-galactosidase (ß-gal) has been demonstrated to be the significant molecular target for visualization of ovarian tumors. Herein, a membrane-permeable fluorescent chemosensor (namely, LAN-ßgal) was synthesized for ß-gal-specific detection using the d-galactose residue as a specific recognition unit and LAN-OH (ΦF = 0.47) as a fluorophore. After ß-gal was digested, the fluorescence of the initially quenched LAN-ßgal (ΦF < 0.001) was enhanced by up to more than 2000-fold, which exceeded the fluorescence enhancement of other previously reported probes. We also demonstrated that the chemosensor LAN-ßgal could visualize endogenous ß-gal and distinguish ovarian cancer cells from normal ovarian cells. Further, the chemosensor LAN-ßgal was successfully applied to visualize the back tumor-bearing mouse model and peritoneal metastatic ovarian cancer model in vivo. More importantly, through in situ spraying, the proposed chemosensor was successfully employed to assist in the surgical resection of ovarian cancer tumors due to its high tumor-to-normal (T/N) tissue fluorescence ratio of 218. To the best of our knowledge, this is the highest T/N tissue fluorescence ratio ever reported. We believe that the LAN-ßgal chemosensor can be utilized as a new tool for the clinical diagnosis and treatment of ovarian cancer.

Visualizing Dipeptidyl Peptidase-IV with an Advanced Non-π-Conjugated Fluorescent Probe for Early Thyroid Disease Diagnosis.

Early detection and effective treatment of thyroid cancer are vital due to the aggressiveness and high mortality rate of the cancer. Nevertheless, the exploration of dipeptidyl peptidase-IV (DPP-IV) as a biomarker for thyroid diseases has not been widely conducted. In this study, we developed a novel non-π-conjugated near-infrared fluorescent probe, MB-DPP4, specifically designed to visualize and detect endogenous DPP-IV. Traditional DPP-IV-specific fluorescent probes rely primarily on the intramolecular charge transfer mechanism. For this reason, these probes are often hampered by high background levels that can inhibit their ability to achieve a fluorescence turn-on effect. MB-DPP4 successfully surmounts several drawbacks of traditional DPP-IV probes, boasting unique features such as exceptional selectivity, ultrahigh sensitivity (0.29 ng/mL), innovative structure, low background, and long-wavelength fluorescence. MB-DPP4 is an "off-on" chemosensor that exhibits strong fluorescence at 715 nm and releases a methylene blue (MB) fluorophore upon interacting with DPP-IV, resulting in a visible color change from colorless to blue. Given these remarkable attributes, MB-DPP4 shows great promise as a versatile tool for advancing research on biological processes and for evaluating the physiological roles of DPP-IV in living systems. Finally, we conducted a comprehensive investigation of DPP-IV expression in human serum, urine, thyroid cells, and mouse thyroid tumor models. Our findings could potentially establish a foundation for the early diagnosis and treatment of thyroid diseases.

Spindle Monitor: A Tool for Real-Time Assessment and Concurrent Treatment of Postoperative Tumor Prognosis.

Cancer surgery remains a mainstay in clinical treatment. However, the efficacy of subsequent therapies largely depends on the precise evaluation of postoperative prognoses, underscoring the critical need for a comprehensive and accurate assessment of surgical outcomes. Nanoprobes targeting tumors offer a promising solution for visual prognostic assessment. In this study, we developed a "Spindle Monitor" system, designated as APPADs (Au NBPs@PDA-pep-AS1411-Dox), composed of core-shell nanoparticles. The core was made up of gold nanobipyramids (Au NBPs), coated with polydopamine (PDA), and subsequently loaded with peptide chains, AS1411, and doxorubicin (Dox). Upon deployment in the acidic tumor microenvironment (TME), APPADs released substantial amounts of Dox, initiating the apoptotic process. This triggered the activity of caspase-3, which is a crucial executor in the apoptotic pathway. Consequently, DEVD, a specific recognition site for caspase-3, was cleaved, enabling the disconnection of FITC-conjugated peptide chains and the recovery of fluorescence. Through assessing this fluorescence imaging effect, local laser irradiation could be precisely guided to the postoperative site, facilitating a synergistic combination of photothermal therapy and chemotherapy. Specifically, our "Spindle Monitor" APPADs had been validated to achieve accurate fluorescence imaging in vitro and in vivo, which demonstrated its potential value as a versatile tool for evaluating postoperative prognosis in surgical treatments, such as thyroid cancer, and assessing chemotherapy efficacy in difficult cases, like late-stage osteosarcoma. This promising tool lays a good foundation for development in visual prognosis evaluation after tumor surgery.

A ratiometric fluorescent sensor for the detection of phosphate.

Over the past few years, ratiometric fluorescent nanoprobes have garnered substantial interest because of their self-calibration characteristics. This research developed a ratiometric fluorescent sensor to detect phosphate. Through encapsulating luminescent materials, gold nanoclusters (AuNCs) and carbon dots (CDs) into a zeolitic imidazolate framework-8 (ZIF-8), the fluorescence signal of AuNCs was enhanced, while that of CDs was suppressed. After phosphate was added, it could decompose ZIF-8, and AuNCs and CDs were released, which weakened the fluorescence signal of the AuNCs while restoring that of the CDs. Thereby, this makes CDs/AuNCs@ZIF-8 a potential fluorescent sensor for phosphate determination. The ratiometric sensor had facile synthesis, good selectivity, and a low detection limit. Therefore, this sensor was an effective tool for the detection of phosphate.

A highly sensitive ratiometric fluorescent probe based on fluorescein coumarin for detecting hydrazine in actual water and biological samples.

Hydrazine (N2 H4 ) is a highly toxic and harmful chemical reagent. Fluorescent probes are simple and efficient tools for sensitive monitoring of N2 H4 enrichment in the environment, humans, animals, and plants. In this work, a ratiometric fluorescent probe (FP-1) containing coumarin was used for hydrazine detection. The proposed FP-1 probe had a linear detection range of 0-250 µM and a limit of detection (LOD) of 0.059 µM (1.89 ppb). A large red Stokes shift was observed in fluorescence and UV-vis absorption spectra due to the hydrolysis of ester bonds between FP-1 and hydrazine. The hydrazine detection mechanism of FP-1 was also investigated using density functional theory (DFT) calculations. Finally, FP-1 could sensitively and selectively monitor hydrazine in actual water samples and BEAS-2B cells. Therefore, it has great application potential in environmental monitoring and disease diagnosis.

Label-Free and Ultrasensitive Detection of Butyrylcholinesterase and Organophosphorus Pesticides by Mn(II)-Based Electron Spin Resonance Spectroscopy with a Zero Background Signal.

Mn(II)-based electron spin resonance (ESR) spectroscopy was used for detecting butyrylcholinesterase (BChE) and organophosphorus pesticides (OPs). MnO2 nanosheets were synthesized with manganese chloride and hydrogen peroxide. With the catalysis of BChE, S-butyrylthiocholine iodide (BTCh) was hydrolyzed into thiocholine which has a reducing -SH group. In the presence of thiocholine, MnO2 nanosheets were broken down and Mn(IV) in MnO2 nanosheets was reduced into Mn(II). Mn2+ is a paramagnetic ion and gives a good ESR signal. In contrast, MnO2 nanosheets have no ESR signal and need not be separated from Mn2+. Mn2+ can be determined directly by ESR spectroscopy, and no further sensing probe is needed. ESR spectroscopy based on directly detecting Mn2+ is much simpler than those using other probes besides MnO2. The ESR signal of Mn2+ is proportional to the catalytic activity of BChE. OPs which inhibit the activity of BChE can also be detected by probing the ESR signal of Mn2+. Since there is no ESR signal of MnO2 nanosheets, the background signal in the absence of BChE was close to zero. The limit of detection (LOD) of BChE was as low as 0.042 U L-1. The standard curve for determining the OP paraoxon was established by measuring the inhibition of BChE by paraoxon, and the LOD of paraoxon was found to be 0.076 ng mL-1. The spiked Chinese cabbage extract samples were analyzed, and the experimental results indicated that the recoveries were from 96.5 to 102.8%. The planted Chinese cabbage was sprayed with the paraoxon solution, and the residue amount of paraoxon in the extract was estimated by the method. The result obtained by the present method was consistent with that obtained by HPLC, which proved the practicability of this new method.

Preparation of a disposable electrochemiluminescence sensor chip based on an MXene-loaded ruthenium luminescent agent and its application in the detection of carcinoembryonic antigens.

Carcinoembryonic antigen (CEA) is an important cancer marker that plays a significant role in achieving low-cost, rapid and highly sensitive clinical detection. In this work, we developed a disposable electrochemiluminescence (ECL) sensor chip based on a screen-printed electrode (SPE) for detecting CEA via ECL technology. An amino-modified Ti3C2 MXene was used as a carrier to successfully prepare a highly efficient ECL probe AuNPs-Ru-Arg@NH2-Ti3C2-MXene by loading with AuNPs-Arg through covalent links and modifying with a ruthenium complex. Upon the addition of CEA, the ECL signal decreased significantly with the increase of CEA, due to the formation of immune complexes at the interface of the electrode. The sensing chip was used to detect CEA in an aqueous solution and found to have a detection limit of 1.5 pg mL-1. The chip was used to determine CEA in the serum of healthy humans and cancer patients, and the results were consistent with those obtained using ELISA. The disposable ECL sensor chip has many advantages including convenience, rapid detection, low cost and easy mass production; thus it has great application potential in clinical cancer diagnosis.

A Ti3C2-MXene-functionalized LRSPR biosensor based on sandwich amplification for human IgG detection.

Long-range surface plasmon resonance (LRSPR) has demonstrated excellent performance in sensing and detection, due to its higher accuracy and sensitivity compared with conventional surface plasmon resonance (cSPR). In this work, we establish an LRSPR biosensor which employs PDA/Ti3C2-MXene/PDA-gold film as a sensing substrate and gold nanoparticles (AuNPs) as enhancers. Ti3C2-MXene is an emerging two-dimensional (2D) layered material which is used extensively in immunoassay and biosensing. The sensing substrate comprises two polydopamine (PDA) films between which is sandwiched a Ti3C2-MXene film based on a gold film, which provides a large surface area and abundant binding sites to rabbit anti-human IgG (Ab1). Sandwich amplification is adopted to enhance the sensitivity of the LRSPR biosensor, and AuNPs/staphylococcal protein A (SPA)/mouse anti-human IgG (Ab2) composites are introduced into the flow cell as enhancers after the immune binding of human IgG to Ab1. The antigen (human IgG) detection range is 0.075 µg mL-1 to 40 µg mL-1, and the limit of detection is almost 20 times lower than that for cSPR biosensors. This novel LRSPR biosensor demonstrates excellent performance in immune sensing over a broad detection range and a low limit of detection. Subsequent modification of the LRSPR sensing platform could be made for extensive application in various biological detection fields.

Ultrabright silicon nanoparticle fluorescence probe for sensitive detection of cholesterol in human serum.

A highly sensitive fluorescence-based assay for cholesterol detection was developed using water-dispersible green-emitting silicon nanoparticles (SiNPs) as a fluorescence indicator and enzyme-catalyzed oxidation product PPDox (Bandrowski's base) as a quencher. The SiNPs were facilely synthesized via a simple, one-step hydrothermal treatment using 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (AEEA) as the silicon source, which has ultrahigh quantum yield and low phototoxicity. Under the catalysis of cholesterol oxidase (ChOx), hydrogen peroxide (H2O2) was generated as a result of cholesterol oxidation. Utilizing p-phenylenediamine (PPD) as the substrate for horseradish peroxidase (HRP) in the presence of H2O2 led to the production of PPDox. Based upon the inner filter effect (IFE), the established ultrasensitive fluorescent assay could accurately measure cholesterol. The limit of detection (LOD) of the assay was 0.018 µM with a linear range of 0.025-10 µM. The results for the detection of real serum samples by the proposed assay were comparable to those by a commercial reagent kit, demonstrating that our proposed strategy has high application potential in disease diagnosis and other related biological studies.

Ratiometric fluorescence and colorimetric dual-mode sensing platform based on carbon dots for detecting copper(II) ions and D-penicillamine.

A sensing platform with both ratiometric fluorescence and colorimetric responses towards copper(II) ions (Cu2+) and D-penicillamine (D-pen) was constructed based on carbon dots (CDs). o-Phenylenediamine (OPD) was employed as a chromogenic development reagent for reaction with Cu2+ to generate the oxidation product 2,3-diaminophenazine (oxOPD), which not only emits green fluorescence at 555 nm, but also quenches the blue fluorescence of CDs at 443 nm via the inner filter effect (IFE) and Förster resonance energy transfer (FRET). Additionally, oxOPD exhibits obvious absorption at 420 nm. Since the intense chelation affinity of D-pen to Cu2+ greatly inhibits the oxidation of OPD, the intensity ratio of fluorescence at 443 nm to that at 555 nm (F443/F555) and the absorbance at 420 nm (A420) were conveniently employed as spectral response signals to represent the amount of D-pen introduced into the testing system. This dual-signal sensing platform exhibits excellent selectivity and sensitivity towards both Cu2+ and D-pen, with low detection limits of 0.019 µM and 0.092 µM, respectively. In addition, the low cytotoxicity of the testing reagents involved in the proposed sensing platform facilitates its application for live cell imaging.

Extraction of parabens by melamine sponge with determination by high-performance liquid chromatography.

In the present study, we propose a novel method for the extraction of parabens in personal care products. A new, simple adsorptive material was obtained by combining metal-organic frameworks and melamine sponges using the adhesive property of polyvinylidene fluoride. This new material, metal-organic frameworks/melamine sponges, was found to be particularly suitable for solid-phase extraction. The structural characteristics of metal-organic frameworks/melamine sponges were first analyzed by scanning electron microscopy. Subsequently, solid-phase extraction was performed on sample solutions, and the extracted substances were then analyzed by high-performance liquid chromatography. Following optimization of important experimental conditions, excellent recovery rates were obtained. Our novel method was then applied to the extraction of four parabens (methylparahydroxybenzoates, ethylparahydroxybenzoates, propylparahydroxybenzoates, and butylparahydroxybenzoates) from real samples. The results yielded limits of detection of 0.26-0.41 ng/mL. The inter- and intra-day recoveries were 104.0-109.7% and 91.2-98.1%, respectively (relative standard deviation, <13.8%).

A sensitive electrochemiluminescent sensor chip based on the ssDNA-Ru(II) complex and aptamer for the determination of thrombin.

In this work, an electrochemiluminescence (ECL) sensor chip for sensitive detection of thrombin (TB) was prepared using a screen-printed electrode (SPE) as a working electrode and an aptamer as a specific recognition moiety. To produce an ECL sensor chip, a layer of pL-Cys was immobilized on the surface of the SPE using the cyclic voltammetry scanning method. A layer of gold nanoparticles (AuNPs) was assembled through an Au-S bond and hairpin DNA was further immobilized on the electrode surface. Ru(bpy)2 (mcpbpy)2+ , as a luminescent reagent, was covalently bound to single-stranded DNA (ssDNA) to prepare a luminescence probe ssDNA-Ru. The probe was hybridized with TB aptamer to form a capture probe. In the presence of TB, the TB aptamer in the capture probe bound to TB, causing the release of ssDNA-Ru that could bind to hairpin DNA on the electrode surface. The Ru(II) complex as a luminescent reagent was assembled onto the electrode, and pL-Cys was used as a co-reactant to enhance the ECL efficiency. The ECL signal of the sensor chip generated based on the above principles had a linear relationship with log TB concentration at the range 10 fM to1 nM, and the detection limit was 0.2 fM. Finally, TB detection using this method was verified using real blood samples. This work provides a new method using an aptamer as a foundation and SPE as a material for the detection of biological substances.

Applications of surface-enhanced Raman spectroscopy based on portable Raman spectrometers: A review of recent developments.

Recently, the surface-enhanced Raman spectroscopy (SERS) technique emerges as a potential promising analytical tool for rapid, sensitive, and selective detection which can provide unique information about the substances in the presence of plasmonic nanostructures via finger-printing SERS spectra. The progress in nanostructure SERS substrates and portable Raman spectrometers will promote this novel detection technique to play an important role in the future rapid on-site assay. In this review, we summarized the latest research on SERS detection technique combined based on nanostructure SERS-active substrates with portable Raman spectrometers and their potential on-site detection applications in environment pollutants, agricultural pollutants, biomedical analysis, and other newly emerging fields (focusing particularly on the last 5 years of research). The future perspective of SERS for on-site analysis is also discussed.

A novel near-infrared fluorescence probe for detecting and imaging Hg2+ in living cells.

Fluorescence imaging, as one of the important means of biological lesion analysis, is widely used in medical analysis. To improve detection specificity, near-infrared emission fluorescent probes have been developed. Sensitive and selective near-infrared (NIR) fluorescent probes for Hg2+ , which is a heavy metal ion harmful to human health, are urgently needed to investigate the physiological toxicity of Hg2+ . The NIR fluorophore based on the traditional structure of rhodamine was prepared by introducing anthocyanin functional groups, and a rhodamine spiro ring structure was constructed to recognize Hg2+ (CCS-Hg). The probe CCS-Hg demonstrated good selectivity and high detection sensitivity for Hg2+ and the most likely mechanism was verified through theoretical calculations. We applied the probe CCS-Hg in the examination of Hg2+ distribution in living cells by NIR fluorescence imaging. This work provides a promising molecular tool for studying the toxicological effects of mercury ions in cell.