One-Step Electrochemical Growth of 2D/3D Zn(II)-MOF Hybrid Nanocomposites on an Electrode and Utilization of a PtNPs@2D MOF Nanocatalyst for Electrochemical Immunoassay

Porphyrin-based nanoscale metal-organic framework nanocarriers entrapping platinum nanoparticles and S-nitrosoglutathione for sonodynamic therapy in hypoxic tumors

Sonodynamic therapy (SDT), which employs acoustic energy to generate reactive oxygen species (ROS), has emerged as a promising strategy for tumor treatment. While ultrasound (US) offers deep tissue penetration and minimal invasiveness, the low energy conversion efficiency of sonosensitizers and the hypoxic tumor microenvironment (TME) significantly limit SDT efficacy. To overcome these challenges, we developed a nano-sonosensitizer, TBP-Hf@Pt-GSNO (Hf-Pt-G), composed of a porphyrin-based nanoscale metal-organic framework (nMOF), TBP-Hf, integrated with platinum nanoparticles (Pt NPs) and S-nitrosoglutathione (GSNO). Pt NPs within the nMOF cavities enhance ultrasound reflection and scattering, thereby improving the acoustic energy conversion efficiency of TBP and boosting SDT efficacy. In addition, Pt NPs can catalyze the conversion of endogenous hydrogen peroxide (H2O2) into oxygen to alleviate tumor hypoxia. US irradiation further triggers the release of nitric oxide (NO) from GSNO, amplifying the killing effect on tumor cells. Enhanced singlet oxygen (1O2) generation and decreased hypoxia inducible factor-1α (HIF-1α) expression were observed in tumor cells following Hf-Pt-G treatment with US irradiation. In vivo, significant tumor suppression was achieved in 4T1 tumor-bearing mice treated with Hf-Pt-G combined with US. This study presents a novel strategy for enhancing acoustic energy conversion while integrating hypoxia alleviation and controllable NO release, thus improving the therapeutic outcomes of SDT.

Electrochemical sensing system based on coordination bond connected porphyrin-MOFs@MXenes hybrids for in situ and real-time monitoring of H2O2 released from cells

Herein, the coordination bond connected porphyrin-MOFs/MXenes composites has been prepared to construct an electrochemical sensing system for in situ and real-time monitoring of H2O2 released by cells. The composites were synthesized by introducing 4-mercaptopyridine and utilizing its binding interaction with titanium in Mxenes and iron in MOFs. This composite was then transferred to the surface of ITO to construct an electrochemical sensing system. The unique properties of Mxenes and porphyrin MOFs endowed the sensing system with excellent electrocatalytic activity, good electrical conductivity and desirable biocompatibility. The electrochemical detections of hydroquinone verified the superior electrochemical performances of the sensing system. The constructed system achieved sensitive electrochemical detection of H2O2 with a detection limit of 3.1 µM and a linear range of 10 µM to 3 mM. Furthermore, the excellent biocompatibility of the composites ensured HeLa cells growth and proliferation on its surface. Based on these favorable properties, the sensing system successfully achieved in-situ and real-time monitoring of H2O2 released by HeLa cells.

Zinc-Organic Gel with Self-Catalysis-Enhanced Electrochemiluminescence as an Emitter for the Evaluation of Liver Cancer Markers

Herein, a novel zinc-organic gel with self-catalysis-enhanced electrochemiluminescence (ECL) performance was prepared as an emitter for the first time to assemble a biosensor for ultrasensitive detection of microRNA-221 (miR-221) related to liver cancer. Interestingly, Zn2+ served as a central ion to coordinate with multidentate ligands 2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine (TATB) at room temperature to form Zn-TATB-MOGs with excellent ECL intensity. More importantly, compared to metal ions (e.g., Al3+, Fe3+, and Eu3+) in the reported MOGs with the role of central ions, Zn2+ in Zn-TATB-MOGs not only served as the central ion but also as a coreaction promoter to facilitate the transformation of S2O82- into free radicals SO4•- to react with Zn-TATB-MOGs•- for further enhancing the ECL signal of Zn-TATB-MOGs. This was the first time to explore the promotion function of metal ions for coreaction reagents and realize the self-catalysis-enhanced ECL of MOGs. Additionally, the double domino-like cascade strand displacement amplification (DC-SDA) methods could overcome the shortcomings of time-consuming procedures and low DNA utilization in traditional cascade-free amplification methods, which significantly shortened the response time of the biosensor and improved the utilization rate of DNA. Consequently, the constructed biosensor achieved ultrasensitive detection of miR-221 with a detection limit of 2.19 aM, which was lower than reported works. This work provided new insight into broadening the development and improving the performance of MOGs as emitters, holding promise for applications in trace detection of biomarkers and early disease diagnosis.

Highly sensitive determination of trace arsenic(III) onto carbon paste electrode modified with graphitic carbon nitride decorated Fe-MOF

An effective electrochemical sensor was developed to detect and determine of the As(III) by modifying the carbon paste electrode (CPE) with graphitic carbon nitride decorated with iron-based metal-organic frameworks (Fe-MOF/g-C3N5). The differential pulse anodic stripping voltammetry (DPASV) method was used to analyze As(III) ions in a phosphate buffer solution (0.10 M, pH = 5). Fe-MOF/g-C3N5/CPE showed high sensitivity (4.24 μA μg-1 L), satisfactory linear range (0.50 μg L-1-5.00 μg L-1 and 5.00 μg L-1-30.00 μg L-1), and low detection limit (LOD, 0.013 μg L-1). The prepared sensor was showed an excellent repeatability and selectivity, and successfully used for determination of the As(III) ion in ambient waters and apple juice samples.

Tunable Structured 2D Nanobiocatalysts: Synthesis, Catalytic Properties and New Horizons in Biomedical Applications

2D materials have offered essential contributions to boosting biocatalytic efficiency in diverse biomedical applications due to the intrinsic enzyme-mimetic activity and massive specific surface area for loading metal catalytic centers. Since the difficulty of high-quality synthesis, the varied structure, and the tough choice of efficient surface loading sites with catalytic properties, the artificial building of 2D nanobiocatalysts still faces great challenges. Here, in this review, a timely and comprehensive summarization of the latest progress and future trends in the design and biotherapeutic applications of 2D nanobiocatalysts is provided, which is essential for their development. First, an overview of the synthesis-structure-fundamentals and structure-property relationships of 2D nanobiocatalysts, both metal-free and metal-based is provided. After that, the effective design of the active sites of nanobiocatalysts is discussed. Then, the progress of their applied research in recent years, including biomedical analysis, biomedical therapeutics, pharmacokinetics, and toxicology is systematically highlighted. Finally, future research directions of 2D nanobiocatalysts are prospected. Overall, this review to provide cutting-edge and multidisciplinary guidance for accelerating future developments and biomedical applications of 2D nanobiocatalysts is expected.

Metalation of metal-organic frameworks: fundamentals and applications

Metalation of metal-organic frameworks (MOFs) has been developed as a prominent strategy for materials functionalization for pore chemistry modulation and property optimization. By introducing exotic metal ions/complexes/nanoparticles onto/into the parent framework, many metallized MOFs have exhibited significantly improved performance in a wide range of applications. In this review, we focus on the research progress in the metalation of metal-organic frameworks during the last five years, spanning the design principles, synthetic strategies, and potential applications. Based on the crystal engineering principles, a minor change in the MOF composition through metalation would lead to leveraged variation of properties. This review starts from the general strategies established for the incorporation of metal species within MOFs, followed by the design principles to graft the desired functionality while maintaining the porosity of frameworks. Facile metalation has contributed a great number of bespoke materials with excellent performance, and we summarize their applications in gas adsorption and separation, heterogeneous catalysis, detection and sensing, and energy storage and conversion. The underlying mechanisms are also investigated by state-of-the-art techniques and analyzed for gaining insight into the structure-property relationships, which would in turn facilitate the further development of design principles. Finally, the current challenges and opportunities in MOF metalation have been discussed, and the promising future directions for customizing the next-generation advanced materials have been outlined as well.

Recent Advances in Metal-Organic Framework (MOF)-Based Composites for Organic Effluent Remediation

Environmental pollution caused by organic effluents emitted by industry has become a worldwide issue and poses a serious threat to the public and the ecosystem. Metal-organic frameworks (MOFs), comprising metal-containing clusters and organic bridging ligands, are porous and crystalline materials, possessing fascinating shape and size-dependent properties such as high surface area, abundant active sites, well-defined crystal morphologies, and huge potential for surface functionalization. To date, numerous well designated MOFs have emerged as critical functional materials to solve the growing challenges associated with water environmental issues. Here we present the recent progress of MOF-based materials and their applications in the treatment of organic effluents. Firstly, several traditional and emerging synthesis strategies for MOF composites are introduced. Then, the structural and functional regulations of MOF composites are presented and analyzed. Finally, typical applications of MOF-based materials in treating organic effluents, including chemical, pharmaceutical, textile, and agricultural wastewaters are summarized. Overall, this review is anticipated to tailor design and regulation of MOF-based functional materials for boosting the performance of organic effluent remediation.

MoO3/MIL-125-NH2 with boosted peroxidase-like activity for electrochemical staphylococcus aureus sensing via specific recognition of bacteriophages

Herein, novel nanozyme mimics MoO3/MIL-125-NH2 were reported and conjugated with bacteriophages as a new electrochemical probe for high sensitivity and specific electrochemical detection of staphylococcus aureus. The excellent peroxidase-like activity of MoO3/MIL-125-NH2 composites was attributed to the integration of MIL-125-NH2 with MoO3, which can boost the generation of superoxide radicals (O• 2-) and thus promote the oxidation of TMB in the presence of H2O2. In this work, two bacteriophages named SapYZU04 and SapYZU10 were isolated from sewage samples by using staphylococcus aureus YZUsa12 as the host. In comparison, MoO3/MIL-125-NH2@SapYZU04 was selected as a recognition agent. The DPV current declined linearly with staphylococcus aureus YZUsa12 concentration in the range of 101-108 CFU mL-1, with a low detection limit of 16 CFU mL-1 (S/N = 3). 20 strains including 13 host strains and 7 non-host strains were used to evaluate the selectivity of the proposed sensor. Regardless of the differences in the degrees of lytic performance for phage SapYZU04, all selected host strains can be screened with merely the same DPV current. Host spectrum-oriented bacteriophage sensing is of great importance for the practical application of bacteriophage-based biosensors in the future.

One-step electrodeposited hybrid nanofilms in amperometric biosensor development

This review summarizes recent developments in amperometric biosensors, based on one-step electrodeposited organic-inorganic hybrid layers, used for analysis of low molecular weight compounds. The factors affecting self-assembly of one-step electrodeposited films, methods for verifying their composition, advantages, limitations and approaches affecting the electroanalytical performance of amperometric biosensors based on organic-inorganic hybrid layers were systemized. Moreover, issues related to the formation of one-step organic-inorganic hybrid functional layers with different structures in biosensors produced under the same electrodeposition parameters are discussed. The systemized dependencies can support the preliminary choice of functional sensing layers with architectures tuned for specific biotechnology and life science applications. Finally, the capabilities of one-step electrodeposition of organic-inorganic hybrid functional films beyond amperometric biosensors were highlighted.

Cathodic deposition of MOF films: mechanism and applications

Metal-organic framework (MOF) thin films could be used for ion/molecular sieving, sensing, catalysis, and energy storage, but thus far no large-scale applications are known. One of the reasons is the lack of convenient and controllable fabrication methods. This work reviews the cathodic deposition of MOF films, which has advantages (e.g., simple operations, mild conditions, and controllable MOF film thickness/morphology) over other reported techniques. Accordingly, we discuss the mechanism of the cathodic deposition of MOF films which consists of the electrochemically triggered deprotonation of organic linkers and the formation of inorganic building blocks. Thereafter, the main applications of cathodically deposited MOF films are introduced with the aim of showing this technique's wide-ranging applications. Finally, we give the remaining issues and outlooks of the cathodic deposition of MOF films to drive its future development.

Mulberry-like porous-hollow AuPtAg nanorods for electrochemical immunosensing of biomarker myoglobin

Mulberry-like AuPtAg porous hollow nanorods (PHNR) were facilely synthesized for the first time via a wet chemical method, where Au nanorods (Au NR) behaved as sacrificed template. The anisotropic oriented growth and etching process are involved in this synthesis. Their structural and electronic characteristics were scrutinously examined by TEM, EDS, XPS, and electrochemical techniques. The AuPtAg PHNR provided a large specific surface area and exposed a large number of active sites, showing highly enhanced catalytic activity. On this foundation, a label-free electrochemical immunosensor was developed for myoglobin (Myo) assay based on the AuPtAg PHNR. Further, the built sensor exhibited fast and ultrasensitive responses in a linear range of 0.0001 ~ 1000 ng mL^-1 with a low limit of detection (LOD = 0.46 pg mL^-1, S/N = 3), and enabled efficient application to human serum samples with acceptable results. Consequently, the developed AuPtAg PHNR-based platform has a broad prospect in practically monitoring Myo and other biomarkers in clinics.

Defect engineering of two-dimensional materials for advanced energy conversion and storage

In the global trend towards carbon neutrality, sustainable energy conversion and storage technologies are of vital significance to tackle the energy crisis and climate change. However, traditional electrode materials gradually reach their property limits. Two-dimensional (2D) materials featuring large aspect ratios and tunable surface properties exhibit tremendous potential for improving the performance of energy conversion and storage devices. To rationally control the physical and chemical properties for specific applications, defect engineering of 2D materials has been investigated extensively, and is becoming a versatile strategy to promote the electrode reaction kinetics. Simultaneously, exploring the in-depth mechanisms underlying defect action in electrode reactions is crucial to provide profound insight into structure tailoring and property optimization. In this review, we highlight the cutting-edge advances in defect engineering in 2D materials as well as their considerable effects in energy-related applications. Moreover, the confronting challenges and promising directions are discussed for the development of advanced energy conversion and storage systems.

One-step synthesis of triethanolamine-capped Pt nanoparticle for colorimetric and electrochemiluminescent immunoassay of SARS-CoV spike proteins

Platinum nanoparticles (PtNPs) have been attracted worldwide attention due to their versatile application potentials, especially in the catalyst and sensing fields. Herein, a facile synthetic method of triethanolamine (TEOA)-capped PtNPs (TEOA@PtNP) for electrochemiluminescent (ECL) and colorimetric immunoassay of SARS-CoV spike proteins (SARS-CoV S-protein, a target detection model) is developed. Monodisperse PtNPs with an average diameter of 2.2 nm are prepared by a one-step hydrothermal synthesis method using TEOA as a green reductant and stabilizer. TEOA@PtNPs can be used as a nanocarrier to combine with antigen by the high-affinity antibody, which leads to a remarkable inhibition of electron transfer efficiency and mass transfer processes. On the basis of its peroxidase-like activity and easy-biolabeling property, the TEOA@PtNP can be used to establish a colorimetric immunosensor of SARS-CoV S-protein thought catalyzing the reaction of H2O2 and 3,3',5,5'-tetramethylbenzidine (TMB). Especially, the Ru(bpy)3 2+ ECL reaction is well-achieved with the TEOA@PtNPs due to their great conductivity and loading abundant TEOA co-reactants, resulting in an enhancing ECL signal in immunoassay of SARS-CoV S-protein. As a consequence, two proposed methods could achieve sensitive detection of SARS-CoV S-protein in wide ranges, the colorimetric and ECL detection limits were as low as 8.9 fg /mL and 4.2 fg /mL (S/N = 3), respectively. We believe that the proposed colorimetric and ECL immunosesors with high sensitivity, good reproducibility, and good stability will be a promising candidate for a broad spectrum of applications.

Recent Trends in Metal Nanoparticles Decorated 2D Materials for Electrochemical Biomarker Detection

Technological advancements in the healthcare sector have pushed for improved sensors and devices for disease diagnosis and treatment. Recently, with the discovery of numerous biomarkers for various specific physiological conditions, early disease screening has become a possibility. Biomarkers are the body's early warning systems, which are indicators of a biological state that provides a standardized and precise way of evaluating the progression of disease or infection. Owing to the extremely low concentrations of various biomarkers in bodily fluids, signal amplification strategies have become crucial for the detection of biomarkers. Metal nanoparticles are commonly applied on 2D platforms to anchor antibodies and enhance the signals for electrochemical biomarker detection. In this context, this review will discuss the recent trends and advances in metal nanoparticle decorated 2D materials for electrochemical biomarker detection. The prospects, advantages, and limitations of this strategy also will be discussed in the concluding section of this review.

Sandwich-type electrochemical immunosensor based on nitrogen-doped porous carbon and nanoporous trimetallic nanozyme (PdAgCu) for determination of prostate specific antigen

A sandwich-type electrochemical immunosensor was designed for the ultrasensitive detection of prostate-specific antigen (PSA), using Au nanoparticles (Au NPs) modified nitrogen-doped porous carbon (NPC) as sensor platform and trimetallic PdAgCu mesoporous nanospheres (PdAgCu MNSs) as enzyme-mimicking labels. NPC was prepared by a facile one-step pyrolysis strategy of biomimetic phylloid zeolite imidazole framework (ZIF-L) nanosheets. Through this strategy, the graphitization of the microcrystalline structure enhanced the electrical conductivity, while its enlarged specific surface area and abundant pore volume can enrich H₂O₂ to improve the catalytic efficiency. Moreover, Au NPs were used to modify NPC without cross-linking agents to further optimize electron transport while capturing primary antibodies, improving stability and sensitivity of the immunosensor. PdAgCu MNSs with uniform size, cylindrical open mesoporous channels, and continuous crystal frame structure were self-assembling synthesized by electrostatic adsorption and ascorbic acid (AA) co-reduction with amphiphilic dioctadecyldimethylammonium chloride (DODAC) as surfactant-cum-micelle, whose unique structure maximizes the use of polyatoms to expose catalytic sites, exhibiting good biocompatibility and electrocatalytic ability. Under the optimal conditions, the immunosensor showed superior sensitivity, a wide dynamic detection range (10 fg mL^-1 ~ 100 ng mL^-1) and a low limit of detection (LOD, 3.29 fg mL^-1). This work provides a convenient strategy for the clinical detection of PSA.