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

A highly sensitive and selective SERS sensors based on Au@PATP@Ag@ZIF-8 for the detection of phosphate in water

Rapid and sensitive detection of phosphate is of great significance for ensuring water safety and preventing eutrophication. In this study, we prepared Au@PATP@Ag NRs core-shell structures using 4-aminothiophenol (PATP) as an internal standard signal molecule to enhance the stability of the SERS signal. Based on the protective effect of ZIF-8 on the internal Au@PATP@Ag NRs and the phosphate-induced decomposition of ZIF-8, a phosphate SERS sensor (Au@PATP@Ag@ZIF-8) with high sensitivity, selectivity and stability was designed. This method exhibited a good linear range of 0.1-125 μM and a detection limit of 30 nM. Furthermore, the developed sensor (Au@PATP@Ag@ZIF-8) was effectively applied to assess PO43- in tap water samples, achieving recoveries between 97.44 % and 104.54 %. With its simple, fast and sensitive features, this method of phosphate detection in water provides a direction for the research and practical application of phosphate detection.

Line-Shifting Triarylmethyl Radicals for Imaging of Enzyme Activity Using Overhauser-Enhanced Magnetic Resonance Imaging: Application to Alkaline Phosphatase

Enzyme catalytic activities are critical biomarkers of tissue states under physiological and pathophysiological conditions. However, the direct measurement and imaging of enzyme activity in vivo remains extremely challenging. We report the synthesis and characterization of the first stable triarylmethyl (TAM) radical substrate of alkaline phosphatase (TAM-ALPs). The enzymatic dephosphorylation of TAM-ALPs results in a drastic change in its electron paramagnetic resonance (EPR) spectrum that can be used to image enzyme activity using EPR-based technologies. TAM-ALPs and their enzyme products were fully characterized using EPR and HPLC-MS techniques. A proof of concept of imaging enzyme activity using Overhauser-enhanced magnetic resonance imaging was demonstrated in vitro. This study clearly demonstrates the potential of EPR-based imaging technologies associated with TAM spin probes to map enzyme activity in vivo in future studies.

Green magnetically separable molluscicide Ba-Ce-Cu ferrite/TiO2 nanocomposite for controlling terrestrial gastropods Monacha Cartusiana

The increasing economic damage caused by terrestrial gastropods, especially the Monacha cartusiana (M. cartusiana) land snail, to the agricultural sector requires a diligent and continuous search for new materials and alternatives for the control operations. In this piece of work, a magnetically separable molluscicide with high effectiveness green Barium-Cerium-Copper ferrite/TiO2 (Ba-Ce-CuFO/TiO2) nanocomposite was greenly prepared using Eichhornia plant aqueous extract and characterized using different techniques. The green Ba-Ce-CuFO/TiO2 nanocomposite was applied as an aspect of the attempts to search for new active substances that would have a potential toxic effect against M. cartusiana. Laboratory toxicity evaluations by leaf dipping and contact methods showed LC50 values of 1218.79 and 289.19 ppm, respectively. Analysis of biochemical variables as a bio response indicator showed a noticeable increase in the values of aspartate transaminase (AST) and alanine transaminase (ALT) relative to the control, while the decrease was characteristic for alkaline phosphatase (ALP) and total protein (TP) other variables when the animals were treated with LC50 value. The histopathological examination was performed on both the muscular foot and the digestive gland, or what is known as the hepatopancreas, which showed enlarged lumens and damaged digestive cells, in addition to destructed digestive tubes, the existence of pyknotic nuclei, and hematocyte infiltration. Foot histopathology showed ruptured epithelial cells, deep folds, and empty spaces when animals were treated with our target nanocomposite LC50 value. Application under natural field conditions through the bait technique showed a significant satisfactory population diminution after 14 days of exposure, as the mean percentage of diminution was 72.2% compared to the recommended pesticide Neomyl SL 20%, which poses a 74.27% reduction. Built on the above, we recommend further studies of the usage of green Ba-Ce-CuFO/TiO2 nanocomposite, and the introduction of such nanocomposite in gastropod control operations to reduce losses in the agricultural sector in general.

Inkjet Printing Patterned Plasmonic SERS Platform with Surface-Optimized Paper for Label-Free Detection of Illegal Drugs in Urine

Rapid quantitative testing of illegal drugs is urgently needed for precisely cracking down on drug crimes. Herein, an optimized paper-based surface-enhanced Raman spectroscopy (SERS) platform with patterned printing of plasmonic nanoparticles was constructed for the on-site quick testing of illegal drugs in urine. The filter paper was first coated with a layer of positive-charged chitosan, so as to reduce its roughness by filling the holes of the cellulose matrix and enhance the adhesion of negative-charged silver ink. Subsequently, hydrophobic modification was performed based on the binary silylation reaction, which could obviously improve the sensitivity of the paper-based SERS substrate by concentrating the amount of analyte. Meanwhile, SERS-active silver ink was fabricated and further printed on the surface of the above modified paper with custom-designed pattern (3 × 6). The performance of this SERS platform was assessed by using crystal violet (CV) as a model tag, and the obtained results proved it possesses excellent sensitivity and reproducibility, in which the relative standard deviation (RSD) dropped remarkably. More importantly, as a proof of concept, rapid detection of standard methylamphetamine (MAMP), one of the most widely abused drugs, was achieved with a limit of detection (LOD) of 1.43 ppb using a portable Raman spectrometer. And it also had a good capability in human urine sample detection, with a correlation index (R2) up to 0.9927. This optimized paper-based SERS platform was easily manufactured, cheap, and portable, providing a new strategy for the on-site detection of illicit drugs.

Zinc porphyrin/MXene hybrids with phosphate-induced stimuli-responsive behavior for dual-mode fluorescent/electrochemiluminescent ratiometric biosensing

Highly sensitive ratiometric biosensors have attracted much attention in biomarker detection, but most rely on single-mode signals, which can affect accuracy. The development of new principles and methods for dual-mode ratiometric sensing can enhance detection accuracy. Herein, the zinc(II) meso-tetra(4-carboxyphenyl) porphyrin/MXene (ZnTCPP/Ti3C2Tx) hybrids with phosphate-induced stimuli-responsive behavior are used to develop a novel dual-mode fluorescent/electrochemiluminescent (FL/ECL) ratiometric biosensor. The composites exhibit FL quenching and enhanced ECL behavior involving dissolved O2. The FL quenching of ZnTCPP/Ti3C2Tx is caused by energy transfer (EnT) and photo-induced electron transfer (PET) from ZnTCPP to Ti3C2Tx. While the introduction of MXene compensates for the inadequate conductivity of ZnTCPP, facilitating electron transfer, which further makes the surface ZnTCPP more capable of activating O2 to produce singlet oxygen (1O2), thereby generating enhanced cathodic ECL. Furthermore, phosphate ions (PO43-) can interact with the Ti sites of ZnTCPP/Ti3C2Tx, leading to competition for coordination with ZnTCPP, which in turn detaches ZnTCPP, resulting in enhanced FL and reduced ECL. On the basis of the phosphate-induced stimuli-responsive behavior, the dual-mode FL/ECL ratiometric biosensing of alkaline phosphatase (ALP) is achieved through ALP-catalyzed production of PO43- cascade effect with ZnTCPP/Ti3C2Tx. The linear detection range for ALP is 0.1-50 mU/mL, with a detection limit as low as 0.0083 mU/mL. This proposed ZnTCPP/Ti3C2Tx composites with stimuli-responsive behavior is expected to provide new ideas for the development of high-sensitivity dual-mode ratiometric biosensors with promising applications in the precise detection of important biomarkers.

Distinguishable Colorimetric Biosensor for Diagnosis of Prostate Cancer Bone Metastases

Castration-resistant prostate cancer (PCa) causes severe bone metastasis (BM), which significantly increases mortality in men with PCa. Imaging tests and radiometric scanning require long analysis times, expensive equipment, specialized personnel, and a slow turnaround. New visualization technologies are expected to solve the above problems. Nonetheless, existing visualization techniques barely meet the urgency for precise diagnosis because the human eyes cannot recognize and capture even slight variations in visual information. By using dye differentiated superposition enhancement colorimetric biosensors, an effective method to diagnose prostate cancer bone metastases (PCa-BM) with excellent accuracy for naked-eye quantitative detection of alkaline phosphatase (ALP) is developed. The biomarker ALP specific hydrolytic product ascorbic acid can be detected by rhodamine derivatives (Rd) as gold nanobipyramids (Au NBPs) are deposited and grown. Color-recombining enhancement effects between Rd and Au NBPs significantly improved abundance. The 150 U L-1 threshold between normal and abnormal can be identified by color. And with color enhancement effect and double signal response, the ALP index is visually measured to diagnose PCa-BM and provide handy treatment recommendations. Additionally, the proposed colorimetric sensing strategy can be used to diagnose other diseases.

Construction of Aggregation-Induced Emission Molecule-MnO2 Composite Nanoprobe and Its Application in Alkaline Phosphatase Detection

Alkaline phosphatase (ALP) is among the most studied enzymes by far, playing an important role in the metabolism of organisms and the regulation of protein activity. Herein, a label-free composite nanoprobe is constructed by combining inorganic nanomaterials and aggregation-induced emission (AIE) molecule to achieve highly sensitive and selective detection of ALP. Negatively charged 9,10-bis [2-(6-sulfonatopropoxyl) naphthylethenyl] anthracene (BSNVA) molecule is synthesized, which has the AIE performance and can be assembled on the surface of amino-SiO₂ nanoparticles through electrostatic interaction for fluorescence enhancement. MnO₂ nanosheets are rich in negative charges, enabling them to be wrapped on the surface of the amino-SiO₂ nanosphere to shield the positive charge on its surface, making it impossible for BSNVA to accumulate on the surface and then weakening the bio-fluorescence of the system. Furthermore, with catalyzed substrates induced by ALP, generating ascorbic acid and the redox reaction between ascorbic acid and MnO₂, the nanoprobe helps in realizing the high-sensitivity detection of ALP with a detection limit of 0.38 mU/mL. The proposed strategy requires no complex cleaning and modification processes and can overcome the quenching effect caused by the aggregation of traditional organic dyes, proving to be a simple, low-cost and "turn-on" fluorescent detection method for ALP.