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[Display omitted] • Successful synthesis of COF@MOF material for Tp-COF@Cu-BDC electrode. • The detection performance of the pristine MOF material was improved. • The fabricated electrode showed good voltammetric response for the detection of 2-AP. • Low LOD and wide detection range for detecting 2-AP were realized. • The reliability, accuracy, and practicality of the sensor were verified. 2-Aminophenol (2-AP) is an organic compound with antibacterial and antioxidant properties in cosmetics, detergents, dyes, and pharmaceuticals. In particular, human health and the environment can be significantly threatened when the concentration of phenolic substances in water reaches 0.1005 mg/L. Hence, there is an urgent need to develop a prompt and accurate analyzing method of 2-AP. To this end, Cu-MOF material was employed as a substrate, and its conductivity and catalytic properties were then enhanced by incorporating Tp-BD-DBd COF within the pores. This COF@MOF composite incorporation, named Tp-COF@Cu-BDC, introduced not only extensive π-conjugated systems but also the mutual electron-donating amino and carboxylate electron-withdrawing groups that may help improve the adsorption capability of 2-AP. Consequently, an increase in conductivity of the Tp-COF@Cu-BDC composite was achieved compared with the MOF monomer. At the same time, the fabricated sensor exhibited a broad detection range (2–250 μM), a low detection limit (0.597 μM), remarkable anti-interference capabilities, and a high recovery rate for 2-AP. Furthermore, the recovery experiment results have proved the actual samples' detection capability based on our electrochemical sensor. Thus, it can be inferred that the COF@MOF composite-based electrochemical sensor is a highly effective platform for detecting 2-AP in environmental settings. [ABSTRACT FROM AUTHOR]

Coral probiotics can improve the tolerance of corals to heat stress, thus mitigating the process of coral thermal bleaching. Sensitive and specific detection of coral probiotics at low abundances is highly desirable but remains challenging, especially for rapid and on-site detection of coral probiotics. Since the electrochemical biosensor has been recently used in the field of environmental DNA (eDNA) detection, herein, an efficient electrochemical biosensor was developed based on CoS 2 /CoSe 2 -NC HNCs electrode material with a specific DNA probe for the C. marina detection. After optimization, the lower limit of detection (LOD) values of such biosensors for the target DNA and genomic DNA were 1.58 fM and 6.5 pM, respectively. On this basis, a portable device was constructed for the practical detection of C. marina eDNA, and its reliability and accuracy were verified by comparison with the ddPCR method (P > 0.05). For each analysis, the average cost was only ∼ $1.08 and could be completed within 100 min with reliable sensitivity and specificity. Overall, the biosensor could reflect the protective effect of probiotics on coral heat stress, and the proposed technique will put new insights into the rapid and on-site detection of coral probiotics to assist corals against global warming. [ABSTRACT FROM AUTHOR]

The coral reef crisis has significantly intensified over the last decades, mainly due to severe outbreaks of crown-of-thorns starfish (COTS). Current ecological monitoring has failed to detect COTS densities at the pre-outbreak stage, thus preventing early intervention. In this work, we developed an effective electrochemical biosensor modified by a MoO 2 /C nanomaterial, as well as a specific DNA probe that could detect trace COTS environmental DNA (eDNA) at a lower detection limit (LOD = 0.147 ng/μL) with excellent specificity. The reliability and accuracy of the biosensor were validated against the standard methods by an ultramicro spectrophotometer and droplet digital PCR (p > 0.05). The biosensor was then utilized for the on-site analysis of seawater samples from SYM-LD and SY sites in the South China Sea. For the SYM-LD site suffering an outbreak, the COTS eDNA concentrations were 0.33 ng/μL (1 m, depth) and 0.26 ng/μL (10 m, depth), respectively. According to the ecological survey, the COTS density was 500 ind/hm2 at the SYM-LD site, verifying the accuracy of our measurements. At the SY site, COTS eDNA was also detected at 0.19 ng/μL, but COTS was not found by the traditional survey. Hence, larvae were possibly present in this region. Therefore, this electrochemical biosensor could be used to monitor COTS populations at the pre-outbreak stages, and potentially serve as a revolutionary early warning method. We will continue to improve this method for picomolar or even femtomolar detection of COTS eDNA. [ABSTRACT FROM AUTHOR]