Simple fluorescence optosensing probe for spermine based on ciprofloxacin-Tb3+ complexation

Supramolecular fluorescent probe based on acyclic cucurbituril for detection of cancer Labels in human urine

Spermine (Spm) and spermidine (Spmd) are considered as potential biomarker for early diagnosis of human cancer. Herein, a novel acyclic cucurbituril derivative (UL-ACB) was firstly designed and synthesized, which fluoresces at 460 nm after excitation at 365 nm. UL-ACB is rich in oxygen atoms which are capable of forming coordinate bonds with copper (Cu²⁺) that cause quenching of UL-ACB fluorescence. Moreover, the addition of biological endogenous substances Spm and Spmd can turn on fluorescence of UL-ACB. Interestingly, the probe showed a remarkable detection efficiency for Spm and Spmd in human urine (the detection limits of Spm and Spmd were 0.156 μM and 0.762 μM, and the linear ranges are 0.156 ∼ 43.06 μM and 0.762 ∼ 29.10 μM), which completely covered the early diagnosis of urinary Spm (1 ∼ 10 μM) and urine Spmd (1 ∼ 20 μM) required concentration range in cancer patients. The probe for Spm and Spmd is simple, time-saving and selective, which may provide a new promising strategy for early cancer diagnosis.

Straightforward smartphone assay for quantifying tannic acid in beverages based on colour change of Eu3+/polyethyleneimine complex

Tannic acid (TA)-a natural product-is a polyphenol derivative that occurs in certain kinds of beverages. A large amount of TA could give rise to an unpleasant flavour and could negatively affect the human body by causing stomach irritation, abdominal pain, nausea, vomiting, and even death. Thus, the need exists for a simple TA detection procedure that meets specific criteria such as on-site analysis, portability, and affordability. Herein, we present a new TA assay, which is based on the fluorescent quenching effect of an efficient fluorophore, and which comprises a smartphone-integrated homemade reader system. The fluorescent polyethyleneimine-derivatised polymer (FP), a strong emitter at 510 nm, was synthesised with the aid of a facile sonication method. In the presence of Eu³⁺ ions, TA quenches the fluorescence of the FP via electrostatic interaction. A smartphone was used to capture an image of the FP undergoing fluorescence for conversion to RGB values. The blue channel was chosen for further analysis because it offered the highest R²-value compared to the red and green channels. We verified these results using a commercial spectrofluorometer and calculated the limit of detection of this assay as 87 nM and 20 nM for the homemade reader and spectrofluorometer, respectively. The detection range for TA with the proposed assay is 0.16-66.66 μM. The application of the proposed method to real beverage samples for TA detection demonstrates its analytical applicability.

A sustainable luminescence-enhanced tri-assembly of polyoxometalate-peptide-polyamine developed for ultrasensitive spermine determination and discrimination

A supramolecular strategy with sustainable emission amplification of an environmentally sensitive polyoxometalate, Na₉[EuW₁₀O₃₆]·32H₂O (EuW₁₀), has been constructed for the Spm determination and discrimination. The EuW₁₀ has no response to Put and other biogenic amine but a sensitive response to Spm (LOD = 0.56 nM) and Spd (LOD = 85.93 nM), respectively. Assembling with a cationic peptide from HPV E6, GL-22, achieved the EuW₁₀/GL-22 assembly, which showed a unique enhanced emission response to Spm and distinguished it from Spd successfully. Furthermore, a synergistic rather than competitive binding of Spm to the EuW₁₀/GL-22 assembly was revealed using FT-IR, and NMR titration spectra, together with DLS and TEM, essentially for the three-component sensing system. Besides, both EuW₁₀ and EuW₁₀/GL-22 assembly were successfully applied to the Spm determination in human urine and serum, suggesting the potential of these sensing approaches in detecting trace amounts of Spm in the clinic. Therefore, the constructed supramolecular assembly can detect the Spm sensitively (LOD = 2.0 nM) and efficiently distinguish it step-wise from other biogenic amines. It is a facile, straightforward, sensitive, and selective strategy for Spm determination and discrimination, which will be helpful in addressing the related biological and clinical requirements.

A quantitative sensing system based on a 3D-printed ion-selective electrode for rapid and sensitive detection of bacteria in biological fluid

Bacterial infections, such as urinary tract infections, are crucial health problems. Here, we report a new potentiometric sensor to detect bacteria sensitively, accurately, and quickly. First, a customizable, 3D printed Ag⁺ selective electrode was fabricated as the probe. Our 3D printed electrode showed sensitive, linear, and selective responses to Ag⁺. Compared to commercial Ag⁺ selective electrodes, ours required less sample volume, shorter responding time, and lower costs. Next, a novel potentiometer was developed with Arduino to couple the electrode for data transducing and transferring, which was programmed to transfer results to cell phones wirelessly. Moreover, a filter was designed to quickly remove interfering species in a biofluid sample (e.g., Cl^-). By detecting the lost Ag⁺ taken by bacteria, the bacterial number could be elucidated. With this sensor system, bacteria numbers could be detected as low as 80 CFU/mL (LOD) within 15 min, which is sufficient for many diagnoses (e.g., urinary tract infection >1000 CFU/mL). An amplification method was presented for single-digit bacteria detection. Overall, we are presenting a bacteria detector with three innovative components: the electrode (signal transduction and detection), the potentiometer (transducer and data processing), and the 3D printed filter (sample preparation), which showed robust and improved (than previously reported ones) analytical merits. The low-cost and customizable (the electrode and the open-source coding) nature enhances the transnationality of the system, especially in underdeveloped areas.