A formaldehyde-assisted metal-ligand crosslinking strategy is used for the synthesis of metal-phenolic coordination spheres based on sol-gel chemistry. A range of mono-metal (Co, Fe, Al, Ni, Cu, Zn, Ce), bi-metal (Fe-Co, Co-Zn) and multi-metal (Fe-Co-Ni-Cu-Zn) species can be incorporated into the frameworks of the colloidal spheres. The formation of coordination spheres involves the pre-crosslinking of plant polyphenol (such as tannic acid) by formaldehyde in alkaline ethanol/water solvents, followed by the aggregation assembly of polyphenol oligomers via metal-ligand crosslinking. The coordination spheres can be used as sensors for the analysis of nucleic acid variants with single-nucleotide discrimination, and a versatile precursor for electrode materials with high electrocatalytic performance.

Nanomaterial/DNA integrated systems have become an emerging tool for intracellular imaging. However, intracellular catalytic DNA circuit is rarely explored. Commonly used nanosystems neglect intracellular DNA assembly, conformation folding and catalytic efficiency, all demanding appropriate metal ion conditions. Herein, MnO 2 nanosheet/DNAzyme (nanozyme) is fabricated as intracellular catalytic DNA circuit generator for high signal amplification, and its operation is reported for monitoring DNA base-excision repair (BER) in living cells with improved performance. MnO 2 nanosheet works as not only DNA nanocarrier but also as DNAzyme cofactor supplier. The nanozyme is constructed by adsorbing DNA probes on MnO 2 nanosheets, facilitating cellular uptake of DNA. They are rapidly released in cellular environments by reducing MnO 2 nanosheets to Mn 2+ as DNAzyme cofactor. After repair enzyme activation, nanozymes are properly assembled with active folded conformation and hold sustained catalytic efficiency over many cycles. It offers at least 40-fold amplified signals for the monitoring of apurinic/ apyrimidinic endonuclease-initiated and DNA glycosylase-initiated BER pathways. Multiplex imaging can be allowed by integrating several sets of probes with per MnO 2 nanosheet. The MnO 2 nanozyme opens up exciting opportunities for imaging low-abundance biomarkers and relevant biological pathways in living cells.

Molecular nanodevices are computational assemblers that switch defined states upon external stimulation. However, interfacing artificial nanodevices with natural molecular machineries in living cells remains a great challenge. Here, we delineate a generic method for programming assembly of enzyme-initiated DNAzyme nanodevices (DzNanos). Two programs including split assembly of two partzymes and toehold exchange displacement assembly of one intact DNAzyme initiated by telomerase are computed. The intact one obtains higher assembly yield and catalytic performance ascribed to proper conformation folding and active misplaced assembly. By employing MnO nanosheets as both DNA carriers and source of Mn as DNAzyme cofactor, we find that this DzNano is well assembled via a series of conformational states in living cells and operates autonomously with sustained cleavage activity. Other enzymes can also induce corresponding DzNano assembly with defined programming modules. These DzNanos not only can monitor enzyme catalysis in situ but also will enable the implementation of cellular stages, behaviors, and pathways for basic science, diagnostic, and therapeutic applications as genetic circuits.

Hydrophobic nanocrystals with various shape, size, and chemical composition were successfully functionalized by poly(amino acid) with one particle per micelle without aggregation or precipitation via a facile, general, and low-cost strategy. Via simply tuning the pH value, multifunctional nanocomposites consisting of different nanocrystals were also fabricated. Due to the poly(amino acid) coating, these nanocrystals are highly water-stable, biocompatible, and bioconjugatable with chemical and biological moieties. Meanwhile, their shape, size, optical/magnetic properties are well retained, which is highly desirable for bioapplications. This developed strategy presents a novel opportunity to apply hydrophobic nanocrystals to various biomedical fields.

Tumor progressions such as metastasis are complicated events that involve abnormal expression of different miRNAs and enzymes. Monitoring these biomolecules in live cells with computational DNA nanotechnology may enable discrimination of tumor progression via digital outputs. Herein, we report intracellular entropy‐driven multivalent DNA circuits to implement multi‐bit computing for simultaneous analysis of intracellular telomerase and microRNAs including miR‐21 and miR‐31. These three biomolecules can trigger respective DNA strand displacement recycling reactions for signal amplification. They are visualized by fluorescence imaging, and their signal outputs are encoded as multi‐bit binary codes for different cell types. The results can discriminate non‐tumorigenic, malignant and metastatic breast cells as well as respective tumors. This DNA computing circuit is further performed in a microfluidic chip to differentiate rare co‐cultured cells, which holds a potential for the analysis of clinical samples.