Scalable copper nanodendrites for next-generation SERS-based biosensors

Scalable, complex geometry of copper nanodendrites (Cu NDs) is highly desirable for next-generation SERS-based biosensors because of the ease of preparation, strong plasmonic response, and lowcost. Highly branched copper nanodendrites (Cu NDs) are fabricated by a non-equilibrium galvanic replacement reaction (GRR) in this work. Remarkably, these Cu NDs create intense field-efficient spots at sharp tips and branch junctions, amplifying bimolecular vibrational signatures leading to superior detection at the trace levels. X-ray diffraction (XRD) and selective area electron diffraction (SAED) analyses indicate preferential growth of Cu NDs in the (111) direction. The versatility of the prepared Cu NDs is demonstrated by their ability to detect multiple biomolecules such as cytosine, adenine, Bovine serum albumin (BSA), and L-cysteine, which are promising biomarkers for early diagnosis of tumors. The sensitivity was evaluated using the analytical enhancement factor (AEF), yielding values of 10⁸ for crystal violet and 10⁴-10⁵ for biomolecules. The estimated limit of detection (LOD) was 138 pM for CV, 27 nM for cytosine, 54 nM for adenine, 64 nM for BSA, and 380 nM for L-cysteine. The signal reproducibility at different locations of the sample surface was demonstrated by a low relative standard deviation (RSD) (∼3%). These results suggest that Cu NDs are robust, versatile, cost-effective, and scalable for future biosensor applications.