Self-enhancement photoelectrochemical strategy for kanamycin determination with amino functionalized MOFs

Preparation of CHS-Fe3O4@@ZIF-8 peroxidase-mimic with an ultra-thin hollow layer for ultrasensitive electrochemical detection of kanamycin

A highly sensitive and selective electrochemical biosensor was developed for the detection of kanamycin using a core-hollow-shell structured peroxidase-mimic nanozyme, CHS-Fe₃O₄@@ZIF-8. The synthesized CHS-Fe3O4@@ZIF-8 was characterized with scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. It was found that the CHS-Fe3O4@@ZIF-8 exhibits excellent peroxidase-like activity due to  its ultra-thin hollow layer. Besides, CHS-Fe3O4@@ZIF-8 functionalized with complementary chains of kanamycin aptamer was anchored to the electrode surface via complementary base pairing with the kanamycin aptamer. Upon the presence of kanamycin, a strand displacement reaction was triggered leading to a reduction in the number of the CHS-Fe3O4@@ZIF-8, which slowed down the catalytic reaction of the substrate 3,3',5,5' -tetramethylbenzidine (TMB) facilitated by CHS-Fe3O4@@ZIF 8. Differential pulse voltammetry (DPV) was employed to measure and record changes in peak current resulting from catalytic oxidation product formation (oxidation product of TMB). The electrochemical signal exhibited a linear relationship with logarithmic variations in kanamycin concentration within a range spanning from 10 to 8000 pM and achieved an impressive detection limit as low as 7.52 pM. Furthermore, successful detection of kanamycin content in serum samples using this sensor demonstrated its good specificity and reproducibility. These findings indicate that the constructed electrochemical kanamycin sensor holds significant potential for practical applications. The biosensor demonstrated high selectivity, distinguishing kanamycin from other antibiotics, and exhibited good reproducibility, making it reliable for practical applications. The successful detection of kanamycin in serum samples further underscores the sensor's potential for real-world applications, particularly in monitoring antibiotic residues in food products and clinical diagnostics.

Recent advances in photoelectrochemical platforms based on porous materials for environmental pollutant detection

Human health and ecology are seriously threatened by harmful environmental contaminants. It is essential to develop efficient and simple methods for their detection. Environmental pollutants can be detected using photoelectrochemical (PEC) detection technologies. The key ingredient in the PEC sensing system is the photoactive material. Due to the unique characteristics, such as a large surface area, enhanced exposure of active sites, and effective mass capture and diffusion, porous materials have been regarded as ideal sensing materials for the construction of PEC sensors. Extensive efforts have been devoted to the development and modification of PEC sensors based on porous materials. However, a review of the relationship between detection performance and the structure of porous materials is still lacking. In this work, we present an overview of PEC sensors based on porous materials. A number of typical porous materials are introduced separately, and their applications in PEC detection of different types of environmental pollutants are also discussed. More importantly, special attention has been paid to how the porous material's structure affects aspects like sensitivity, selectivity, and detection limits of the associated PEC sensor. In addition, future research perspectives in the area of PEC sensors based on porous materials are presented.

Copper(II)-MOFs for bio-applications

The recent development and implementation of copper-based metal-organic frameworks in biological applications are reviewed. The advantages of the presence of copper in MOFs for relevant applications such as drug delivery, cancer treatment, sensing, and antimicrobial are highlighted. Advanced composites such as MOF-polymers are playing critical roles in developing materials for specific applications.

Electrochemiluminescent (ECL) biosensor for Burkholderia pseudomallei based on cobalt-doped MOF decorated with gold nanoparticles and N-(4-aminobutyl)-N-(ethylisoluminol)

A multifunctional catalytic nanomaterial (Co-MOF@AuNP@ABEI) composed of cobalt-doped metal-organic frameworks (Co-MOF), gold nanoparticles (AuNP), and N-(4-aminobutyl)-N-(ethylisoluminol) (ABEI) is reported. Co-MOF@AuNP@ABEI exhibits high synergistic and zero-distance catalytic properties, which are beneficial to the improvement of the detection sensitivity of an electrochemiluminescent (ECL) biosensor. After coupling with the ECL system and 3D magnetic walking nanomachine amplification strategy, the Co-MOF@AuNP@ABEI can achieve an ultrasensitive ECL assay of Burkholderia pseudomallei with the limit of detection (LOD) of 60.3 aM, which is 2 and 4 orders of magnitude lower than individual ECL system without the nanomachine (4.97 fM) and individual walking nanomachine (340 fM), and superior to the pathogenic bacteria analyses in the previous report. Moreover, the LOD of the proposed ECL detection system for the determination of B. pseudomallei in serum sample was as low as 9.0 CFU mL^-1. The relative standard deviations (RSD) of ECL intensity for the detection of five B. pseudomallei-spiked serum samples were 4.02%, 0.84%, 0.84%, 1.55%, and 0.21%, respectively. The recoveries of the ECL biosensor for the detection of B. pseudomallei DNA-spiked serum samples were 93.63 ~ 107.83%. Therefore, this work demonstrated that the developed multifunctional catalytic nanomaterial with synergistic and zero-distance catalytic properties can be used as excellent ECL signal reporter to improve the detection sensitivity of ECL biosensor.