A multifunctional nano system based on DNA and CeO2 for intracellular imaging of miRNA and enhancing photodynamic therapy

Fluorimetric determination of tetracycline antibiotics in animal derived foods using boron and nitrogen co-doped ceria-based nanoparticles

An innovative synthesis of boron and nitrogen co-doped ceria-based nanoparticles (B/N-CeFNPs) with bright blue fluorescence emission is reported using the hydrothermal method. Based on the aggregation-induced emission enhancement (AIEE) effect between B/N-CeFNPs and chlortetracycline (CTC), a rapid detection method for CTC through fluorescence enhancement was developed. In addition, through the electron transfer process (ET), fluorescence resonance energy transfer (FRET) effect and static quenching between B/N-CeFNPs and oxytetracycline (OTC), a ratio fluorescence strategy for detecting OTC was generated. The fluorescence of B/N-CeFNPs at 410 nm can be effectively quenched by OTC, and new fluorescence emission appears at a wavelength of 500 nm. B/N-CeFNPs showed good linear responses with CTC and OTC in the range 0.1-1 µM and 1-40 µM, respectively. This system was used to simultaneously detect the CTC and OTC in milk and honey, realizing multi-residues detection of TCs in actual samples by using the same ceria-based fluorescence nanomaterial.

Self-assembly of molecular beacons through metal ion coordination for fluorescence imaging of miRNA in living cells

Fluorescence nanosensors based on functional nucleic acids have been explored as a powerful sensing platform for disease-relevant miRNAs. This work developed a new hybrid nanosensor (Zr-B) through coordination-driven self-assembly of Zr ions and beacons. The prepared nanosensor exhibited high loading efficiency of beacons and could achieve sensitive and specific detection for miRNAs. The hybrid nanosensor could transfer beacons into living cells efficiently and maintain high stability and biocompatibility in the biological environment, achieving effective miRNA fluorescence imaging in living cells. Therefore, the resultant nanosensor holds potential for applications in disease diagnostics.

A GSH-activated AIE-based polymer photosensitizer for killing cancer cells

Developing efficient photosensitizers which are sensitive to therapeutic tumor signals, but non-toxic to normal cells has always been a tremendous challenge in photodynamic therapy (PDT) process. Herein, a novel copolymer P1 was developed by ring-opening metathesis polymerization (ROMP) with disulfide bond linked ferrocene-norbornene dyad NB-SS-PyFc and the aggregation-induced emission (AIE) fluorephore anchored norbornene NB-TPE, and its nanoparticles (NPs) were obtained by using the amphiphilic Pluronic F-127 as the surfactant via a nanoprecipitation method. The P1 NPs show a weak emission and a low ¹O₂ generation for the quenching effect from the ferrocene moiety to the AIE group. However, the addition of GSH can recover the AIE fluorephore emission and ¹O₂ generation for cleavage the disulfide bond. Importantly, P1 NPs have been used for image-guided cancer cells apoptosis for the GSH activated ¹O₂ generation.

Nanoceria: an innovative strategy for cancer treatment

Nanoceria or cerium oxide nanoparticles characterised by the co-existing of Ce³⁺ and Ce⁴⁺ that allows self-regenerative, redox-responsive dual-catalytic activities, have attracted interest as an innovative approach to treating cancer. Depending on surface characteristics and immediate environment, nanoceria exerts either anti- or pro-oxidative effects which regulate reactive oxygen species (ROS) levels in biological systems. Nanoceria mimics ROS-related enzymes that protect normal cells at physiological pH from oxidative stress and induce ROS production in the slightly acidic tumour microenvironment to trigger cancer cell death. Nanoceria as nanozymes also generates molecular oxygen that relieves tumour hypoxia, leading to tumour cell sensitisation to improve therapeutic outcomes of photodynamic (PDT), photothermal (PTT) and radiation (RT), targeted and chemotherapies. Nanoceria has been engineered as a nanocarrier to improve drug delivery or in combination with other drugs to produce synergistic anti-cancer effects. Despite reported preclinical successes, there are still knowledge gaps arising from the inadequate number of studies reporting findings based on physiologically relevant disease models that accurately represent the complexities of cancer. This review discusses the dual-catalytic activities of nanoceria responding to pH and oxygen tension gradient in tumour microenvironment, highlights the recent nanoceria-based platforms reported to be feasible direct and indirect anti-cancer agents with protective effects on healthy tissues, and finally addresses the challenges in clinical translation of nanoceria based therapeutics.

DNA nanolantern-mediated catalytic hairpin assembly nanoamplifiers for simultaneous detection of multiple microRNAs

Simultaneous detection of multiple microRNAs (miRNAs) with high sensitivity can give accurate and reliable information for clinical applications. By uniformly anchoring hairpin probes on the surface of DNA nanolantern, a three-dimensional DNA nanostructure contains abundant and adjustable modification sites, highly integrated DNA nanoprobes were designed and developed as catalytic hairpin assembly (CHA)-based signal amplifiers for enzyme-free signal amplification detection of target miRNAs. The nanolantern-based CHA (NLC) amplifiers, which were facilely prepared via a simple "one-pot" annealing method, showed enhanced biostability, improved cell internalization efficiency, accelerated CHA reaction kinetics, and increased signal amplification capability compared to the single-stranded DNA hairpin probes used in traditional CHA reaction. By co-assembling multiple hairpin probes on a DNA nanolantern surface, as-prepared NLC amplifiers were demonstrated to work well for highly sensitive and specific imaging, expression level fluctuation analysis of two miRNAs in living cells, and miRNAs-guided tumor imaging in living mice. The proposed DNA nanolantern-based nanoamplifier strategy might provide a feasible way to promote the cellular and in vivo applications of nucleic acid probes.

5,10,15,20-tetrakis (4-carboxyl phenyl) porphyrin-functionalized urchin-like CuCo2O4 as an excellent artificial nanozyme for determination of dopamine

Urchin-like peroxidase mimics 5,10,15,20-tetrakis (4-carboxyl phenyl) porphyrin-functionalized CuCo2O4 nanospheres (Por-CuCo2O4) has been fabricated as an excellent visual biosensor. X-ray diffractometry (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) have been employed to characterize the composition, morphologies, and elemental analysis of the as-synthesized Por-CuCo2O4. The catalytic activity of Por-CuCo2O4 was evaluated by the chromogenic substrate 3,3',5,5'-tetramethylbenzidine (TMB) with the aid of H2O2, which exhibited a visual blue change with an absorption maximum at 652 nm for only 10 s. The peroxidase-like behaviors of Por-CuCo2O4 conformed to the Michaelis-Menten equation. Electrochemistry, radical scavenger, and fluorescence probe experiments verified that electron transfer, •O2- radicals, and holes (h+) are the important factors during the catalytic oxidation of TMB. Based on the inhibition of dopamine (DA) on TMB oxidation, the Por-CuCo2O4-based colorimetric biosensor has been successfully constructed for sensitive determination of DA witha detection limit (LOD) of 0.94 μΜ. In addition, colorimetry was validated to detect DA in serum samples with high sensitivity and good selectivity. 5,10,15,20-tetrakis (4-carboxyl phenyl) porphyrin-functionalized urchin-like CuCo2O4 (Por-CuCo2O4) with excellent peroxidase activity, ascribed to the synergistic effect between •O2- radicals and holes (h+). A fast colorimetric sensor on the basis of Por-CuCo2O4 has been constructed to quantitatively determine dopamine concentration in human serums.