Biomineralized flexible metal nanofilms with surface plasmon resonance for adhesion of heterogeneous materials

Flexible substrates with metal deposition layers are widely used in the fabrication of wearable devices. However, metal deposition processes are often complex and unsatisfactory due to the multifaceted interplay between deposition conditions and substrate properties. Therefore, it is crucial to find a convenient and effective method to improve the bonding between flexible substrates and metal interfaces. In this study, a phase transition protein-induced gold mineralization strategy is proposed to enhance the metal-substate interactions by facilitating gold deposition onto flexible substrates adhered with phase transition proteins. The self-assembly and conformational adaptation of phase transition proteins (including lactalbumin, lysozyme, and bovine serum albumin) driven by disulfide bond cleavage, provide abundant binding sites and stabilize the structure, enabling the reliable mineralization of gold ions on flexible substrates. The resulting gold-modified flexible substrates maintain the inherent flexibility of the original materials while manifesting excellent surface-enhanced Raman scattering (SERS) properties, reproducibility, and mechanical durability, exhibiting compatibility with various substrates, which can be applied for the detection of methotrexate in urine with a wide range from 10⁻⁸ to 10⁻³ M. This research provides a biomimetic approach to optimize metal adhesion on flexible materials and contributes to the development of biocompatible and stable metal-coated flexible materials.