Comparative toxicology of algal cell extracts and pure cyanotoxins: insights into toxic effects and mechanisms of harmful cyanobacteria Raphidiopsis raciborskii.

Ongoing research on cyanotoxins, driven by the socioeconomic impact of harmful algal blooms, emphasizes the critical necessity of elucidating the toxicological profiles of algal cell extracts and pure toxins. This study comprehensively compares Raphidiopsis raciborskii dissolved extract (RDE) and cylindrospermopsin (CYN) based on Daphnia magna assays. Both RDE and CYN target vital organs and disrupt reproduction, development, and digestion, thereby causing acute and chronic toxicity. Disturbances in locomotion, reduced behavioral activity, and weakened swimming capability in D. magna have also been reported for both RDE and CYN, indicating the insufficiency of conventional toxicity evaluation parameters for distinguishing between the toxic effects of algal extracts and pure cyanotoxins. Additionally, chemical profiling revealed the presence of highly active tryptophan-, humic acid-, and fulvic acid-like fluorescence compounds in the RDE, along with the active constituents of CYN, within a 15-day period, demonstrating the chemical complexity and dynamics of the RDE. Transcriptomics was used to further elucidate the distinct molecular mechanisms of RDE and CYN. They act diversely in terms of cytotoxicity, involving oxidative stress and response, protein content, and energy metabolism, and demonstrate distinct modes of action in neurofunctions. In essence, this study underscores the distinct toxicity mechanisms of RDE and CYN and emphasizes the necessity for context- and objective-specific toxicity assessments, advocating nuanced approaches to evaluate the ecological and health implications of cyanotoxins, thereby contributing to the precision of environmental risk assessments.

Gd-modified Mn-Co oxides derived from layered double hydroxides for improved catalytic activity and H2O/SO2 tolerance in NH3-SCR of NOx reaction.

Metal oxides derived from layered double hydroxides (LDHs) are expected to obtain low-temperature denitrification (de-NOx) catalysts with high catalytic activity and H2O/SO2 tolerance in the selective catalytic reduction (SCR) of NOx with NH3. In current work, we successfully prepared Gd-modified Mn-Co metal oxides derived from Gd-modified Mn-Co LDHs. The resultant Gd-modified Mn-Co metal oxides exhibit excellent catalytic activity and high H2O/SO2 tolerance in the NH3-SCR de-NOx reaction. The reasons for the enhancement can be ascribed to the unique surface physicochemical properties inherited from LDHs and the modification of Gd, which increase the specific surface area, improve the relative content of Mn4+ and Co3+ on the surface, enhance the number of acidic sites, strengthen the reducibility of catalyst, resulting in the enhanced catalytic activity and H2O/SO2 tolerance. Additionally, it is demonstrated that the NH3-SCR de-NOx reaction occurred on the surface of Gd-modified Mn-Co oxides followed both Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms. This study provides us with a design approach to promote catalytic activity and H2O/SO2 tolerance through morphology control and rare earth modification.

Point-of-care detection of glycated hemoglobin using a novel dry chemistry-based electrochemiluminescence device.

As a good biomarker to reflect the average level of blood glucose, glycated hemoglobin (HbA1c) is mainly used for long-term glycemic monitoring and risk assessment of complications in diabetic patients. Previous analysis methods for HbA1c usually require complex pretreatment processes and large-scale biochemical analyzers, which makes it difficult to realize the point-of-care testing (POCT) of HbA1c. In this work, we have proposed a three-electrode dry chemistry-based electrochemiluminescence (ECL) biosensor and its self-contained automatic ECL analyzer. In this enzymatic biosensor, fructosyl amino-caid oxidase (FAOD) reacts with the hydrolysis product of HbA1c, and the produced hydrogen peroxide further reacts with luminol under the appropriate driving voltage, generating photons to realize the quantitative detection of HbA1c. Under optimized conditions, the biosensors have a good linear response to different concentrations of fructosyl valine (FV) ranging from 0.05 to 2 mM, with a limit of detection of 2 µM. The within-batch variation is less than 15%, and the biosensors still have 78% of the initial response after the accelerated aging test of 36 h at 37 °C. Furthermore, the recoveries for different concentrations of samples in whole blood were within 92.3-99.7%. These results illustrate that the proposed method has the potential for use in POCT of HbA1c.

A dry chemistry-based electrochemiluminescence device for point-of-care testing of alanine transaminase.

Liver disease causes serious public health problems because of its high prevalence, particularly affecting low- and middle-income countries. Alanine transaminase (ALT) is considered to be one of the most sensitive indicators for diagnosing liver disease. Although many strategies have been reported for ALT detection, few of them have solved the problem of automatic detection. In this work, for the first time, a dry chemistry-based electrochemiluminescence (DC-ECL) device is developed for point-of-care testing (POCT) of ALT, achieving real sample-to-answer detection. The proposed DC-ECL device consists of the following two components: (a) a DC-ECL chip consisting of the outer shell (including the top cap and pedestal) and detection layer (including the baseplate, electrode pad and carrier pad) and (b) an automatic ECL analyzer mainly including the data processing and instrument control unit, imaging detection unit, electrochemical reaction excitation unit, open detection window unit and rechargeable power supply. Under optimized conditions, the device had a wide detection range (0-1000 U/L), the ECL intensity linearly increased with ALT concentration (5-50 U/L) and logarithmic ALT concentration (50-1000 U/L), and the limit of detection was calculated to be 1.702 U/L. In addition, the DC-ECL device had the ability to measure ALT levels in human serum samples and showed acceptable selectivity, stability and repeatability. These results reveal that the DC-ECL device can overcome the disadvantages of traditional methods for ALT detection (such as high cost and requirement of professional technicians) and potentially opens the door to the development of similar POCT analyzers.