The precise control of the assembly structure and size of gold nanoclusters (AuNCs) can potentially amplify their near-infrared II (NIR-II) fluorescence imaging and targeting properties. However, the conventional electrostatic assembly of AuNCs and charged molecules faces challenges in balancing the inherent electrostatic repulsions among charged units and regulating the diffusion of assembly units. These difficulties limit precise control over assembly size and structure, along with limited options for coassembled molecules, thereby restricting imaging properties and targeting capability. To circumvent this challenge, we developed a reverse emulsion-confined electrostatic assembly method. This technique efficiently constructs AuNC nanoassemblies with diverse coassembled molecules, allowing for the fine-tuning of assembly size and structure, including both core–satellite and homogeneous AuNC nanoassemblies. The development of two distinct nanoassemblies can be partially attributed to the varying diffusive rates of AuNCs or the AuNCs/polymer complex within the fused emulsion droplets. This variance arises from steric hindrances encountered during the emulsion fusion process. Interestingly, core–satellite nanoassemblies exhibit the strongest NIR-II fluorescence enhancement. Finally, the introduction of a hyaluronic acid coating on the surfaces of nanoassemblies with varying sizes enables the nanoprobes to achieve enhanced lymph node imaging through size modulation and macrophage targeting, which are used for surgical navigation to remove lymph node metastases. We envision that this self-assembly strategy can be extended to a wide range of electrostatic assembly systems for the development of multicomponent functional materials.
Hongyan Xue,Youmei Han,Guanglei Liu,Wenjing Chen,Zhihang Wang,Nong Wang
Surfactants play a crucial role in applications such as oil-water separation, foam flotation , drug delivery, emulsion polymerization , and emulsifier recovery. Stimulus-responsive surfactants, as innovative smart materials, can reversibly control emulsion decomposition or phase transformation, facilitating emulsion circulation and component recovery. In this paper, two short-chain fluoroazobenzene photoresponsive surfactants ( FADC-2 and FADC-4 ) were synthesized. Three different reversible emulsion systems were constructed, leveraging the excellent chemical stability and rapid photoresponse of azobenzene and the trifluoromethyl group as a hydrophobic moiety. The results indicate that under different light exposures, the FADC-2 /n-hexane/water and FADC-4 /n-hexane/water emulsions exhibit reversible emulsification and demulsification cycles, while the FADC-4 /n-octanol/water emulsions show reversible phase transfer. These findings highlight the effectiveness of photoresponsive surfactants in controlled emulsion systems, offering promising applications in fields requiring precise emulsion manipulation and liquid-liquid phase transfer, at the same time advancing the development of environmentally friendly, practical, durable, and stimulus-responsive surfactants.
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