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.

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.

Polygalae Radix: review of metabolites, pharmacological activities and toxicology.

Polygalae Radix: is the dried root of Polygala tenuifolia Willd. or Polygala sibirica L., which has the effect of improving memory and cognitive function in traditional Chinese medicine. Modern pharmacological studies indicated that Polygalae Radix has rich pharmacological activities in vitro and in vivo, including protective effects on the nervous system, immune system, cardiovascular system and respiratory system, as well as antioxidant and antiepileptic pharmacological activities. Up to now, more than 160 metabolites from Polygalae Radix were identified, including triterpenoid saponins, xanthones, oligosaccharide esters and et al. The clinical practice of traditional Chinese medicine has proved that Polygalae Radix has a certain irritation to the throat, and a large or long-term use will stimulate the digestive tract, and the main toxic metabolite is saponins. Therefore, Polygalae Radix should be pr ocessed or used in combination with other Chinese herbal medicines to reduce the irritation to the throat and reduce gastrointestinal irritation. This article provides a review of the metabolites, pharmacological activity, and toxicology of Polygalae Radix. It also discusses the future research prospects and existing problems of Polygalae Radix, providing reference for further research on Polygalae Radix.

Synthesis of in-situ magnetized MOF-cellulose membranes for high-efficiency enrichment of diamide insecticides in vegetables and determination by LC-MS/MS.

This study presents a novel, eco-friendly composite adsorbent material designed for the magnetic solid-phase extraction of diamide insecticides from vegetable samples. The membrane, denoted as Fe-MMm, was incorporated with a cellulose framework embedded with Metal-Organic Frameworks (MOFs) and Multi-Walled Carbon Nanotubes (MWCNTs) magnetized with Fe3O4. This innovative material streamlined the conventional solid-phase extraction process, simplifying the sample pre-treatment. By combining it with liquid chromatography tandem mass spectrometry (LC-MS/MS), the method achieves significantly enhanced extraction efficiency through systematic optimization of experimental parameters, including adsorbent selection, pH, ionic strength, adsorption time, and elution time. The method had a wide linear range of 0.1-1000 ng/mL and an exceptionally low detection limit ranging from 0.023 to 0.035 ng/mL. The successful identification of diamide insecticides in vegetable samples underscores the potential of Fe-MMm as a robust material for sample pretreatment in analytical applications.

A dual-response ratiometric fluorescent sensor for oxytetracycline determination in milk and mutton samples.

Owing to the adverse effects of oxytetracycline (OTC) residues on human health, it is of great importance to construct a rapid and effective strategy for OTC detection. Herein, we developed a dual-response fluorescence sensing platform based on molybdenum sulfide quantum dots (MoS2 QDs) and europium ions (Eu3+) for ratiometric detection of OTC. The MoS2 QDs, synthesized through an uncomplicated one-step hydrothermal approach, upon OTC integration into the MoS2 QDs/Eu3+ sensing system, exhibit a significant quenching of blue fluorescence due to the inner filter effect (IFE), simultaneously enhancing the distinct red emission of Eu3+ at 624 nm, a phenomenon attributed to the antenna effect (AE). This sensor demonstrates exceptional selectivity and sensitivity towards OTC, characterized by a linear detection range of 0.2-10 µM and a notably low detection limit of 2.21 nM. Furthermore, we achieved a visual semi-quantitative assessment of OTC through the discernible fluorescence color transition from blue to red under a 365 nm ultraviolet lamp. The practical applicability of this sensor was validated through the successful detection of OTC in milk and mutton samples, underscoring its potential as a robust tool for OTC monitoring in foodstuffs to safeguard food safety.

A portable front face fluorescent system for in situ detection of aluminum in flour foods.

A simple and rapid method for in situ detection of aluminum in flour food was developed by using a self-made portable front face fluorescent system (PFFFS). The effects of pH, temperature, reaction time, protective agent and masking agent on the detection of Al3+ were investigated. The use of fluorescent probe protective agent, interfering ion masking agent, multi-point collection measurements and the working curves based on the analyte content in the real samples makes the present method have high accuracy, selectivity and reliability for in situ detection of Al3+ in flour foods. By comparison with the ICP-MS the accuracy and reliability of the present method were verified. The results showed that when 97 real samples were analyzed the Al3+ content values obtained by the present method and those obtained by ICP-MS method reached a highly significant correlation, with r ranging from 0.9747 to 0.9844. The self-made PFFFS combined with fluorescent probe does not require sample digestion, and can quickly detect Al3+ in flour food within 10 min. Therefore, the present method based on using FFFS has good practical application value for in-situ rapid detection of Al3+ in flour foods.

Reversible fluorescent test strip with red fluorescent carbon dots for monitoring water in organic solvents: Visual detection via a smartphone.

Herein, a novel type of red-emitting carbon dots called TN-CDs was created via a one-step hydrothermal approach using neutral red and tartaric acid as raw materials. The fluorescence of TN-CDs was gradually quenched as the amount of water increased, and the color of the solution changed from yellow to pink mauve (or purple to pink). The reaction could be completed within only 5 s in various organic solvents such as N,N-Dimethylformamide (DMF), methanol (MeOH), acetonitrile (ACN), and ethanol (EtOH) with linear detection ranges of 1.2%-35.0%, 0.5%-20.0%, 0.25%-5.0% and 0%-16.0%, respectively. In addition, we prepared a reusable test strip and then combined it with TN-CDs to detect water content in DMF, as well as integrated it with smartphone software, a UV lamp, and a dark chamber for real-time, on-site, visual quantitative detection of the water content.

2-Amino-anilinium 6-carb-oxy-picolinate monohydrate.

In the title compound, C(6)H(9)N(2) (+)·C(7)H(4)NO(4) (-)·H(2)O, one amino group of diamino-benzene is protonated while one carb-oxy group of pyridine-2,6-dicarb-oxy-lic acid is deprotonated. In the anion, the CO(2) and CO(2)H groups make dihedral angles of 4.0 (5) and 8.7 (4)° with the pyridine ring. In the crystal, extensive N-H⋯O, N-H⋯N and O-H⋯O hydrogen bonds occur between anions, cations and water mol-ecules.

Determination of protein by resonance light scattering technique using dithiothreitol-sodium dodecylbenzene sulphonate as probe.

The resonance light scattering (RLS) spectra of bovine serum albumin (BSA)-dithiothreitol (DTT)-sodium dodecylbenzene sulphonate (SDBS) and its analytical application were investigated. The RLS intensity of this system can be effectively enhanced in the presence of BSA. Based on the enhanced RLS intensity, a simple assay for BSA was developed. The experimental results indicate that the enhanced RLS intensity is proportional to the concentration of BSA in the range from 1.0 x 10(-8) to 7.5 x 10(-7) mol L(-1) with the determination limit of 5.0 x 10(-9) mol L(-1). The effects of pH, concentration of SDBS and DTT on the RLS enhancement were discussed. Most metal ions have little interference on the determination of BSA. Some synthetic and real samples were analyzed, and the results obtained were in good agreement with those obtained by Bradford method.

Determination of serum albumin in the presence of poly(diallyldimethylammonium chloride) by resonance light scattering technique.

By means of the resonance light scattering (RLS) technique, a new method was developed to determine the bovine serum albumin (BSA) and human serum albumin (HSA) by the interaction of serum albumin with poly(diallyldimethylammonium chloride) (PDDA). At Tris-NaOH buffer solution, the RLS intensity of serum albumin at the wavelength 320, 550 and 590 nm was obviously enhanced in the presence of PDDA. The influences of some experimental factors, including incubation time, addition sequence of reagents, pH value, concentration of PDDA and foreign substances, on the enhancement of the RLS intensity were examined. The optimum conditions of the experiment were selected. Under the selected experimental condition, the enhanced RLS intensities were directly proportional to the concentrations in the range of (0.0250-2.75)x10(-6) mol/L for BSA and (0.0235-1.17)x10(-6) mol/L for HSA. The detection limits (S/N=3) were 8.40x10(-9) mol/L for BSA and 7.39x10(-9) mol/L for HSA. The synthetic samples were analysed and the results obtained were satisfactory.

Resonance light scattering technique for the determination of proteins with polymethacrylic acid (PMAA).

As a resonance light scattering (RLS) probe, the polyelectrolyte polymethacrylic acid (PMAA) was applied in this assay. The bovine serum albumin (BSA) and human serum albumin (HSA) were determined by the electrostatic interaction of PMAA and proteins. At pH 3.8 Na(2)HPO(4)-citric acid buffer solution, the RLS intensities of PMAA-BSA (HSA) system were greatly enhanced. The characteristic peaks were appeared at the wavelength 320, 546 and 594 nm. The optimization conditions of the reaction were also examined and selected. Under the selected conditions, the RLS intensities were proportional to the protein concentrations in the range of (0.0200-2.00) x 10(-6) mol/L for BSA and (0.0200-2.40) x 10(-6) mol/L for HSA. The influences of some foreign substances were also examined. The synthetic samples containing proteins and some real samples were analyzed and the results obtained were satisfactory.

Determination of bovine serum albumin using resonance light scattering technique with sodium dodecylbenzene sulphonate-cetyltrimethylammonium bromide probe.

In this paper, the anionic surfactant sodium dodecylbenzene sulphonate (SDBS) and cationic surfactant cetyltrimethylammonium bromide (CTMAB) were used as resonance light scattering (RLS) probe to determine bovine serum albumin (BSA). Based on the weak RLS intensity of SDBS-CTMAB probe and the enhancement of RLS intensity of BSA in the presence of the probe, a simple assay for BSA was developed. The experimental results showed that the formation of three component complex BSA-SDBS-CTMAB is the main reason for the enhancement of RLS intensity of BSA, in which SDBS as a bridge can interact with both BSA and CTMAB. The effects of pH value, incubation time, concentrations of SDBS and CTMAB on the enhanced RLS intensity of BSA were investigated. Under the optimum conditions, the enhanced RLS intensity is proportional to the concentration of BSA in the range from 2.5 x 10(-8) to 2.0 x 10(-6)mol L(-1). The detection limit is 9.7 x 10(-9) mol L(-1) for BSA. The study of foreign substance effect on the determination of BSA indicated that most of metal ions have little effect on the determination of BSA. The results of assay for BSA in synthetic samples were satisfactory.

Investigation on hyperin-cetyltrimethylammonium bromide-fibronectin system by resonance light-scattering technique.

A simple, highly sensitive assay for fibronectin (Fn) was reported using resonance light-scattering (RLS) technique based on the enhanced RLS intensity of hyperin-cetyltrimethylammonium bromide (CTMAB)-Fn system. The interaction system of hyperin-CTMAB-Fn was investigated using spectral methods. Mechanistic investigations show that the main reason of the enhanced RLS intensity of Fn is the formation of three-component complex (hyperin-CTMAB-Fn), in which CTMAB acts as a bridge between hyperin and Fn. The effects of pH, surfactant, concentration of CTMAB and hyperin, incubation time and foreign substances on the enhancement of RLS intensity were studied. Under the optimum conditions, the enhancement of RLS intensity is in proportion to the concentration of Fn in the range of 1.9-248ng/ml. The synthetic samples containing Fn were analyzed and results obtained were satisfied.

Investigation on the interaction between colloidal gold and human complement factor 4 at different pH by spectral methods.

The interaction between colloidal gold and human complement factor 4 (human C4) at different pH was investigated by spectral methods, including absorption and resonance light-scattering spectrometry. According to the changes of color and absorption spectra of colloidal gold solution in presence of human C4, the interaction between colloidal gold and human C4 was quantitatively investigated using a semi-empirical "flocculation parameter". At the same time, the changes of resonance light-scattering spectra and transmission electron microscopy (TEM) images indicate that the aggregation of colloidal gold happens by electrostatic interaction in presence of human C4 in the pH range 5-6. However, the colloidal gold solution remains stable at pH >6 and pH <5 due to the repulsive electrostatic interaction between colloidal gold and human C4. The flocculation parameter is directly proportional to the concentration of human C4 in the range from 9.7 to 233.0 microgl(-1). In addition, the interactions between the colloidal gold and bovine serum albumin (BSA) as well as human serum albumin (HSA) were also investigated using the same methods. It was found that there was no aggregation of colloidal gold in presence of BSA and HSA in the pH range 5-6. However, when the pH of solution is 4, the aggregation of colloidal gold happens. Because BSA and HSA have different structure, the intensity of aggregation of colloidal gold in presence of BSA is greater than that in presence of HSA at pH 4.

Determination of human complement factor C4 using resonance light-scattering technique with sodium dodecylbenzene sulphonate probe.

Based on the interaction between human complement factor C4 (human C4) and sodium dodecylbenzene sulphonate (SDBS) and the resonance light-scattering (RLS) technique, a highly sensitive assay for human C4 using resonance light-scattering technique was developed. At pH 2.8 Na2HPO4-citric acid buffer solution, the RLS intensities of SDBS system at 283, 503 and 600 nm were obviously enhanced in the presence of human C4. The effects of surfactant, pH, incubation time, concentration of SDBS and foreign substances on the enhanced RLS intensity of system were investigated. Under the optimum conditions, the enhanced RLS intensity is directly proportional to the concentration of human C4 in the range of (0.5-120)x10(-6)gl-1 and the linear regression equation was obtained with high correlation coefficient. This RLS technique was applied to the determination of human C4 in some synthetic samples with good recovery. Moreover, it was found that the electrostatic interaction is the main binding force between SDBS and human C4.

A FRET-based fluorescent probe for mercury ions in water and living cells.

On the basis of fluorescence resonance energy transfer (FRET), a new rhodamine derivative (DRh) was synthesized as a ratiometric fluorescent probe for detecting Hg(2+) in water and living cells samples. The recognition properties of the probe DRh with metal ions had been investigated in H2O/CH3CN (9:1, v/v; Tris-HCl 50mmolL(-1); pH=7.0) solution by the UV-Vis spectrophotometry and the fluorescence spectrophotometry. The results showed that the probe DRh exhibited the selective recognition of Hg(2+). Upon the addition of Hg(2+), the spirolactam ring of probe DRh was opened. The 1:1 stoichiometric structure between DRh and Hg(2+) were supported by Job's plot, MS and DFT theoretical calculations. The linearly fluorescence intensity ratio (I582/I538) is proportional to the concentration of Hg(2+) in the range 0-30µmolL(-1). The limit of detection (LOD) of Hg(2+) is 0.008µmolL(-1) (base on S/N=3). The present probe was applied to the determination of Hg(2+) in neutral water samples and gave recoveries ranging from 104.5 to 107.9%. Furthermore, the fluorescent probe also can be applied as a bioimaging reagent for Hg(2+) detection in HeLa cells.

Studies on the interaction of colloidal gold and serum albumins by spectral methods.

The interactions of colloidal gold and serum albumins, including bovine serum albumin (BSA) and human serum albumin (HSA), were studied by fluorescence and absorption spectrometry. Fluorescence quenching spectrometry was applied to study the interactions between colloidal gold and serum albumins. At pH 7.4 phosphate-buffered saline (PBS), the intensity of fluorescence emission spectrum of serum albumins decreased in the presence of colloidal gold, which indicated that colloidal gold quenched the fluorescence of serum albumins. Experimental results indicated that the combination reactions of colloidal gold and serum albumins were static quenching processes. Based on the effect of colloidal gold on fluorescence intensity, the binding constants, the numbers of binding sites and the acting forces between colloidal gold and serum albumins were found.