We report on a novel dibenzothiophene-based two-photon fluorescent probe for selective nuclear bioimaging, which contains bilaterally symmetrical pyridine rings connected by a central conjugated-bridge dibenzothiophene. This probe possesses a large two-photon absorption cross-section of 471 GM, yields a 25-fold enhancement of the fluorescence titration, and a stronger photostability for nuclei labeling than existing probes. The real-time observation period is a minimum of 1800 s under a femtosecond laser excitation, which is significantly longer than that of 4′,6-diamidino-2-phenylindole. The above results confirm that this novel molecule is a suitable two-photon fluorescent probe for application to nuclear bioimaging in cells.

Metal hydrazone complex thin films are used as laser patterning materials, and the patterns with a minimum resolution of about 78 nm are successfully obtained by the laser writing setup (λ=405 nm, NA=0.9). The minimum resolution is only about 1/8 of the writing spot size. In the formation of patterns, there is only a single step for forming patterns by the laser heating-induced clear thermal gasification threshold effect without any other development processes such as wet etching. This work provides an effective method for directly achieving nanoscale-resolved pattern structures with diode-based maskless laser writing lithography at visible light wavelengths.