Hydrogel core-shell micropattern achieved by Fs-MOPL technique in one-step

For the first time, the femtosecond laser maskless optical projection lithography (Fs-MOPL) technique enables the one-step fabrication of Ag@methacrylamide chitosan/poly(ethylene glycol) diacrylate (Ag@MP) micropatterns, which serve as SERS substrates with high biocompatibility and antibacterial activity.

The work, published in the International Journal of Extreme Manufacturing, presents a flexible and efficient strategy for producing multifunctional microstructures, with promising applications in biosensing, biomedical imaging, and antimicrobial surface technologies.

Prof. Zheng’s research group at Technical Institute of Physics and Chemistry, Chinese Academy of Sciences (CAS) has focused on the femtosecond laser fabrication of functional materials for decades. “Various methods used to prepare Ag/CS nanomaterials usually require multiple steps, high temperatures and long preparation time.” said Fanchun Bin, the first author of the paper and a doctoral candidate at CAS. “Self-designed patterns are widely used in various fields. Therefore, why not combine the function of core-shell nanomaterials and micropatterns at the same time via a more convenient preparation method?”

Chitosan (CS) is one of the most widely used biopolymers in the preparation of nanoparticles (NPs). The antimicrobial and combat infection characteristics of CS can be enhanced by combining it with silver NPs, making Ag/CS NPs promising for biomedical and biotechnological applications.

To facilitate the preparation of these Ag/CS nanomaterials, the Fs-MOPL technique provides a highly efficient solution, enabling the fabrication of large-area micro-nano structures in one-step in a short time.

Different Ag@MP micropatterns were fabricated by Fs-MOPL, with NPs made up of a silver core and a hydrogel shell. The size distribution of NPs can be effectively controlled by adjusting the exposure time. Localized Surface Plasmon Resonanc (LSPR) effect on the silver surface induces the formation of core-shell structures, while the generation of silver particles follows the nucleation and growth mechanism.

The researchers found that amino and hydroxyl groups can promote the nucleation process, resulting in the increase of particle number. The acid inhibits the formation of silver nuclei but supports the growth of silver cores compared to a neutral environment. Furthermore, the SERS performance, biocompatibility and antibacterial rate of Ag@MP substrates have been studied, making them suitable for use in biotechnological and biomedical fields.

“In this work, we primarily focus on hydrogel-based core-shell structures. We expect that more types of polymers and metal salts will be used in the fabrication of core-shell nanomaterials,” said Meiling Zheng, corresponding author and Professor at CAS. “Fs-MOPL, as a simple and efficient technique, can be applied across a wide range of fields.”

About IJEM:

International Journal of Extreme Manufacturing (IF: 16.1, consecutive 1st in the Engineering, Manufacturing category) is a multidisciplinary and double-anonymous peer-reviewed journal uniquely publishing original articles and reviews of the highest quality and impact in the areas related to extreme manufacturing, ranging from fundamentals to process, measurement, and systems, as well as materials, structures, and devices with extreme functionalities.

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