Chemical–biological approaches for the direct regulation of cell–cell aggregation

Cell–cell aggregation is one of the most well-known modes of intercellular communication.The aggregation also plays a vital role in the formation of multicellularity,thus manipulating the growth and development of organisms.In the past decades,cell–cell aggregation-related bioprocesses and molecular mechanisms have attracted enormous interest from scientists in biology,and bioengineering.People have developed a series of strategies to artificially regulate cell–cell aggregation through chemical–biological approaches.To date,not only the chemical reagents such as coordination compounds and polymers but also the biomacromolecules such as proteins and nucleic acids,are employed as the“cell glue”to achieve the control of the cell aggregation.So it is meaningful to review the recent advances of the chemical–biological approaches in cell–cell aggregation manipulation.In this review,we discuss the mechanisms and features of recently developed strategies to control cell–cell aggregation.We introduce molecules and designs relying on chemical reactions and biological conjugations respectively,and talk about their advantages and suitable applications.A perspective on the challenges in future applications in cell manipulation and cell-based therapy is also proposed.We expect this review could inspire innovative work on manipulating cell–cell aggregation and further modulate cell–cell interactions in the research of bio/chemical fields.

Ultra-bright near-infrared-IIb emitting Zn-doped Ag_(2)Te quantum dots for noninvasive monitoring of traumatic brain injury

The long-wavelength region of the near-infrared-IIb(NIR-IIb,1,500–1,700 nm)imaging window has become an ideal window for in vivo imaging due to the suppressed photon scattering and near-zero autofluorescence of biological tissues.Therefore,it is necessary to develop fluorescent probes with excellent fluorescence performance and stability for NIR-IIb fluorescence imaging.In this work,zinc-doped silver telluride quantum dots(Zn:Ag_(2)Te QDs)with bright fluorescence in the NIR-IIb window were synthesized.The introduction of Zn dopants inhibited crystal defects and reduced non-radiative transitions.Therefore,the quantum yield and fluorescence lifetime of Zn:Ag_(2)Te QDs were significantly improved.In addition,Zn-doping increased the number of ligands on the surface of QDs,thus enhancing the colloidal stability of Zn:Ag_(2)Te QDs.Moreover,the PEGylated Zn:Ag_(2)Te QDs with high absolute quantum yield realized noninvasive imaging of cerebral vascular of mouse with high resolution able to distinguish blood capillary,which could be utilized to monitor the brain condition of mice after traumatic brain injury.

Programmable and Reversible Regulation of Catalytic Hemin@MOFs Activities with DNA Structures

Metal-organic frameworks(MOFs)-based nanozyme plays an important role in biosensing,therapy and catalysis.In this study,the effects of single-stranded DNA(ssDNA)with programmable sequences and its complementary DNA(Tdna)on the intrinsic peroxidase-like activity of hemin loaded MOFs(UiO-66-NH2),denoted as he-min@UiO-66-NH2,were investigated.The hemin@UiO-66-NH2 exhibited improved catalytic activity compared with free hemin.However,the catalytic activity is inhibited in the presence of ssDNA,as ssDNA can be adsorbed by MOFs and therefore protected the active sites from contact with substrates.Upon the addition of the TDNA,double-stranded DNA(dsDNA)was formed and detached from the MOFs,resulting in the recovery of catalytic activity.Sequentially adding ssDNA or its complementary DNA strands can achieve the reversible regulation of the catalytic activity of MOFs nanozymes.Moreover,the DNA hybridization-based regulation was further applied to a cascaded catalytic system composed of the nanozyme,hemin@UiO-66-NH2,and glucose oxidase.These nanozyme based programmable and reversibly regulated catalytic systems may have potential applications in future smart biosensing and catalysis systems.

Meta-DNA Strategy to Assemble DNA Structures in Submicrometre and Micrometre Scale

To break through the size limitation in DNA structure assembly and to achieve the construction of DNA structures with submicrometre and micrometre scale,Fan and Yan et al.proposed a versatile DNA structure assembly strategy,named as meta-DNA(M-DNA)strategy.Submicrometre-sized M-DNA,which has a six-helix bundle DNA origami nanostructure,is used as building block to precisely assemble a series of submicrometre-to-micrometre-sized DNA architectures with customed shapes,including meta-multi-arm junctions,polyhedrons and closely packed lattices.Besides static assembly,the proposed M-DNA strategy was also demonstrated to work well for the programmed dynamic rearrangement of DNA structures.This work has been published online in the Nature Chemistry on September 7,2020.

Rational design and structural regulation of near-infrared silver chalcogenide quantum dots

Silver chalcogenides(Ag_(2)E;E=S,Se,or Te)quantum dots(QDs)have emerged as promising candidates for near-infrared(NIR)applications.However,their narrow bandgap and small exciton Bohr radius render the optical properties of Ag_(2)E QDs highly sensitive to surface and size variations.Moreover,the propensity for the formation of silver impurities and their low solubility product constants pose challenges in their controllable synthesis.Recent advancements have deepened our understanding of the relationship between the multi-hierarchical structure of Ag_(2)E QDs and their optical properties.Through rational design and precise structural regulation,the performance of Ag_(2)E QDs has been significantly enhanced across various applications.This review provides a comprehensive overview of historical and current progress in the synthesis and structural regulation of Ag_(2)E QDs,encompassing aspects such as size control,crystal structure engineering,and surface/interface engineering.Additionally,it discusses outstanding challenges and potential opportunities in this field.The aim of this review is to promote the custom synthesis of Ag_(2)E QDs for applications in biological imaging,and optoelectronics applications.

Monitoring Neovascularization of Malignant Solid Tumors with Horseradish Peroxidase-Functionalized Near-Infrared-II PbS Quantum Dots

The growth and metastasis of malignant solid tumors depend closely on newblood vessels. Vasculogenic mimicry provides a special pathway of blood supply during theearly growth of malignant tumors, and real-time monitoring of its occurrence anddevelopment in vivo is important to clinical applications. However, there are few labelswith sufffcient brightness and stability in vivo to achieve high spatiotemporal resolutionimaging of deep tissue for noninvasive optical detection of vasculogenic mimicry in tumortissues. In this study, we constructed a high-brightness ffuorescent label with ffuorescence inthe near-infrared-II region, which can be used not only for in vivo tumor imaging but also fortissue section imaging. Real-time high-resolution imaging of tumor vessels has been achievedwith PbS quantum dots (QDs) surface-coupled with horseradish peroxidase (HRP) (HRPQDs) by taking advantage of the low background autoffuorescence of tissue at the nearinfrared-II wavelength for in vivo and tissue section imaging. Qualitative and quantitativeanalysis of early blood supply patterns of tumor growth enables monitoring neovascularizationto accurate noninvasive identiffcation of benign and malignant solid tumors.