β-Cyclodextrin derived full-spectrum fluorescent carbon dots: The formation process investigation and biological applications

Carbon dots(CDs), a new building unit, have been revolutionizing the fields of biomedicine, bioimaging, and optoelectronics with their excellent physical, chemical, and biological properties. However, the difficulty of preparing excitation-dependent full-spectrum fluorescent CDs has seriously hindered their further research in fluorescence emission mechanisms and biomedicine. Here, we report full-spectrum fluorescent CDs that exhibit controlled emission changes from purple(380 nm) to red(613 nm) at room temperature by changing the excitation wavelength, and the excitation dependence was closely related to the regulation of sp2 and sp3 hybrid carbon structures by β-cyclodextrin-related groups. In addition,by regulating the content of β-cyclodextrin, the optimal quantum yields of full-spectrum fluorescent CDs were 8.97%, 8.35%, 7.90%, 9.69% and 17.4% at the excitation wavelengths of 340, 350, 390, 410 and 540 nm,respectively. Due to their excellent biocompatibility and color tunability, full-spectrum fluorescent CDs emitted bright and steady purple, blue, green, yellow, and red fluorescence in MCF-7 cells. Moreover, we optimized the imaging conditions of CDs and mitochondrial-specific dyes;and realized the mitochondrialtargeted co-localization imaging of purple, blue and green fluorescence. After that, we also explored the effect of full-spectrum fluorescent CDs in vivo fluorescence imaging through the intratumorally, subcutaneously, and caudal vein, and found that full-spectrum fluorescent CDs had good fluorescence imaging ability in vivo.

An emerging quaternary semiconductor nanoribbon with gate-tunable anisotropic conductance

Two-dimensional noble transition metal chalcogenide(NTMC)semiconductors represent compelling building blocks for fabricating flexible electronic and optoelectronic devices.While binary and ternary compounds have been reported,the existence of quaternary NTMCs with a greater elemental degree of freedom remains largely unexplored.This study presents the pioneering experimental realization of a novel semiconducting quaternary NTMC material,AuPdNaS_(2),synthesized directly on Au foils through chemical vapor deposition.The ribbon-shaped morphology of the AuPdNaS_(2)crystal can be finely tuned to a thickness as low as 9.2 nm.Scanning transmission electron microscopy reveals the atomic arrangement,showcasing robust anisotropic features;thus,AuPdNaS_(2)exhibits distinct anisotropic phonon vibrations and electrical properties.The field-effect transistor constructed from AuPdNaS_(2)crystal demonstrates a pronounced anisotropic conductance(σ_(max)/σ_(min)=3.20)under gate voltage control.This investigation significantly expands the repertoire of NTMC materials and underscores the potential applications of AuPdNaS_(2)in nano-electronic devices.