Danyang Cui,Wenhui Fang,Aijun Li,Aijun Li,Shenghan Wang,Zhiwei Men,Zhiwei Men
Lowering the threshold and enhancing the intensity of stimulated Raman scattering (SRS) has been a major topic in nonlinear optics. In this work, we investigated the SRS characteristic of ethanol with graphene quantum dots (GQDs) through a Nd: YAG laser with wavelengths of 532 and 355 nm, respectively. Pure ethanol solution exhibits SRS characteristic peaks at 2943 cm-1, attributed to the symmetric stretching vibration of -CH3, the maximum energy conversion efficiency was 9.51% with 532 nm laser excitation. GQDs interact with a laser in a nanostructure environment, the edge effects of GQDs enhance light–matter interaction, contributing to localized surface plasmon resonance (LSPR) under resonant excitation, resulting in an electric field enhancement on SRS, decreasing the SRS threshold. The laser wavelength of 355 nm, which falls within the absorption band of GQDs, triggers the quantum confinement effects of GQDs, leading to the emission of fluorescence and the generation of intense LSPR. The synergistic interaction between LSPR and fluorescence enhancement effect further amplifies the SRS signal and activates the strong third-order SRS, yielding a remarkable energy conversion efficiency of 29.67% with the GQDs concentration of 0.2 mg/mL. These findings demonstrate that GQDs serve as highly efficient nonlinear optical mediators, representing an excellent candidate for advancing SRS-based photonic devices.
Granular hydrogels are a kind of bulk hydrogel that are densely assembled by microparticles, showing great potential in 3D bioprinting. To develop a granular hydrogel-based bioink with enhanced strength, the present study combined methacryloylated gelatin (GelMA) with granular hydrogel to fabricate a compound bioink. Poly (γ-glutamic acid) (PG) microspheres and hydroxy propyl chitosan (CSPO) microspheres were fabricated, respectively, and self-assembled via charge interaction between microspheres to form a granular hydrogel after adding GleMA solution. However, its assembly ability decreased with the increase of the content of CSPO microspheres. The composite granular hydrogel with same mass content of PG microspheres and CSPO microspheres showed superior storage modulus, shear-thinning and self-healing ability. The composite granular hydrogels carrying adiposed derived stem cells (ASCs) showed well-performed extrudability and fidelity. In addition, after printing, UV light was used for further cross-linking GelMA, forming multi-networks that significantly improve the strength of the printed engineered tissue. ASCs proliferated significantly in bioink. The composite granular hydrogel thus showed great potential as bioink with enhanced strength for cell printing.
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