A fluorescent dye, 2,5-bis(6-amine-benzoxazol-2-yl)thiophene (BBTA), was synthesized by a two-step reaction from starting material 2,5-bis(benzoxazol-2-yl)thiophene (BBT). BBTA exhibited strong emission and large Stokes shift in solvent, and the largest Stokes shift (Δλ = 186 nm or Δν = 8572 cm⁻¹) was obtained in buffer solution (PBS, pH = 7.2) with 5% (v/v) of polyethylene glycol monomethyl ether (mPEG₅₅₀, MW = 550) as additive. Application of BBTA to live cell imaging showed that BBTA was clearly expressed in mitochondria with high contrast. Besides, BBTA showed low cytotoxicity and excellent photo-stability.

It’s critically important to construct arbitrary inorganic features with high resolution. As an inorganic photoresist, hydrogen silsesquioxane (HSQ) has been patterned by irradiation sources with short wavelength, such as EUV and electron beam. However, the fabrication of three- dimensional nanoscale HSQ features utilizing infrared light sources is still challenging. Here, we demonstrate femtosecond laser direct writing (FsLDW) of HSQ through multi-photon absorption process. 26 nm feature size is achieved by using 780 nm fs laser, indicating super-diffraction limit photolithography of λ/30 for HSQ. HSQ microstructures by FsLDW possess nanoscale resolution, smooth surface, and thermal stability up to 600 °C. Furthermore, we perform FsLDW of HSQ to construct structural colour and Fresnel lens with desirable optical properties, thermal and chemical resistance. This study demonstrates that inorganic features can be flexibly achieved by FsLDW of HSQ, which would be prospective for fabricating micro-nano devices requiring nanoscale resolution, thermal and chemical resistance.

We propose an asymmetric three-dimensional (3D) multiphoton polymerization microfabrication method, and successfully demonstrate it through fabricating the size- and shape-controlled stimuli-responsive asymmetric hydrogel microcantilevers. The reversible ion-responsive hydrogel microcantilevers exhibit attractive and controllable bending behavior due to their asymmetric deformation to external ions. The reversible bending direction of microcantilevers completed within only 0.133 s when the surrounding environment was alternated from water to 1 M NaCl solution. Furthermore, the microcantilevers exhibited large total bending angles θ_T up to 32.9°. The bending behavior can be also strongly influenced by increasing the length of the microcantilevers. The 3D stimuli-responsive hydrogels were demonstrated to be promising for the application of microactuators and micromanipulators. This designable microfabrication technique and the stimuli-responsive behavior of asymmetric microstructure of hydrogel with versatility in the shape would be prospective for developing biomedical microdevices.