Rectangular coordination polymer nanoplates: large-scale, rapid synthesis and their application as a fluorescent sensing platform for DNA detection

Integrated Antibody with Catalytic Metal-Organic Framework for Colorimetric Immunoassay

Enzyme-linked immunosorbent assay has been widely used as a gold standard in biomedical field, but some inevitable drawbacks still exist in its practical applications, especially the laborious preparation of enzyme-antibody conjugates by a covalent linkage. In this work, we proposed a new strategy to prepare enzyme-antibody conjugate by integrating antibody with catalytic metal-organic framework (MOF) to form dual-functional MOF/antibody composite. As models, rabbit antimouse immunoglobulin G antibody (RIgG) and Cu-MOF with peroxidase-like activity were used to fabricate RIgG@Cu-MOF composite for colorimetric immunoassay. It was found that Cu-MOF as a host not only has no influence on the original capture ability of RIgG to its corresponding antigen (mIgG), but also can shield RIgG against long-term storage, high temperature, and biological degradation. More importantly, upon the formation of sandwiched immunocomplex between RIgG@Cu-MOF and capture antibody, Cu-MOF can serve as a signal amplification unit to perform colorimetric immunoassay. The detection limit of RIgG@Cu-MOF toward mIgG was obtained at 0.34 ng/mL, which is 3-fold lower than that of horseradish peroxidase labeled RIgG. Furthermore, the successful determination of mIgG in serum sample demonstrates the applicability of RIgG@Cu-MOF in detecting real sample. Therefore, it is highly anticipated that this study can offer a new way to prepare enzyme-antibody conjugates, facilitating the exploration of MOF composites in biomedical field.

Two-dimensional metal–organic framework nanosheets: synthesis and applications

Synthesis and applications of two-dimensional metal–organic framework nanosheets and their composites are summarized.

Mixed ligand two dimensional Cd(ii)/Ni(ii) metal organic frameworks containing dicarboxylate and tripodal N-donor ligands: Cd(ii) MOF is an efficient luminescent sensor for detection of picric acid in aqueous media

Two water stable MOFs [M(BrIP)(TIB)]_n [M = Cd(ii), Ni(ii)] have been prepared. Cd(ii) MOF serves as photoluminescent sensor for detection of TNP in aqueous phase.

Ultrathin 2D Metal-Organic Framework Nanosheets

A facile surfactant-assisted bottom-up synthetic method to prepare a series of freestanding ultrathin 2D M-TCPP (M = Zn, Cu, Cd or Co, TCPP = tetrakis(4-carboxyphenyl)porphyrin) nanosheets with a thickness of sub-10 nm is developed. As a proof-of-concept application, some of them are successfully used as new platforms for DNA detection. The Cu-TCPP nanosheet-based sensor shows excellent fluorescent sensing performance and is used for the simultaneous detection of multiple DNA targets.

Fabrication of fluorescent SiO2@zeolitic imidazolate framework-8 nanosensor for Cu2+ detection

The formation of core–shell SiO₂@ZIF-8 nanostructures for Cu²⁺ detection is reported here.

Fabrication of Bioactive Surfaces by Functionalization of Electroactive and Surface-Active Block Copolymers

Biofunctional block copolymers are becoming increasingly attractive materials as active components in biosensors and other nanoscale electronic devices. We have described two different classes of block copolymers with biofuctional properties. Biofunctionality for block copolymers is achieved through functionalization with appropriate biospecific ligands. We have synthesized block copolymers of electroactive poly(3-decylthiophene) and 2-hydroxyethyl methacrylate by atom transfer radical polymerization. The block copolymers were functionalized with the dinitrophenyl (DNP) groups, which are capable of binding to Immunoglobulin E (IgE) on cell surfaces. The block copolymers were shown to be redox active. Additionally, the triblock copolymer of α, ω-bi-biotin (poly(ethylene oxide)-b-poly (styrene)-b-poly(ethylene oxide)) was also synthesized to study their capacity to bind fluorescently tagged avidin. The surface-active property of the poly(ethylene oxide) block improved the availability of the biotin functional groups on the polymer surfaces. Fluorescence microscopy observations confirm the specific binding of biotin with avidin.

Direct and freely switchable detection of target genes engineered by reduced graphene oxide-poly(m-aminobenzenesulfonic acid) nanocomposite via synchronous pulse electrosynthesis

A novel one-step electrochemical synthesis of the reduced graphene oxide and poly(m-aminobenzenesulfonic acid, ABSA) nanocomposite (PABSA-rGNO) via pulse potentiostatic method (PPM) for direct and freely switchable detection of target genes is presented. Unlike most electrochemical preparation of hybrids based on rGNO and polymer, electrochemical synthesis of PABSA (during the pulse electropolymerization period of PPM) and electrochemical reduction of rGNO (during the resting period of PPM), in this paper, were alternately performed. The total progress synchronously resulted in PABSA-rGNO nanocomposite. This nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), Fourier Transform infrared spectroscopy (FT-IR), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The PABSA-rGNO nanocomposite integrated graphene (a single-atom thick, two-dimensional sheet of sp(2) bonded conjugated carbon) with PABSA (owning rich-conjugated structures, functional groups, and excellent electrochemical activity), which could serve as an ideal electrode material for biosensing and electrochemical cell, etc. As an example, the immobilization of the specific probe DNA was successfully conducted via the noncovalent method due to the π-π* interaction between conjugated nanocomposite and DNA bases. The hybridization between the probe DNA and target DNA induced the product dsDNA to be released from conjugated nanocomposite, accompanied with the self-signal regeneration of nanocomposite ("signal-on"). The self-signal changes served as a powerful tool for direct and freely switchable detection of different target genes, and the synergistic effect of PABSA-rGNO nanocomposite effectively improved the sensitivity for the target DNA detection.