Mechanoplasmonics: Integrating nanoplasmonic materials and stiffness tunable hydrogels for real-time, label-free cellular analysis

Understanding how cellular biochemical states respond to mechanical stimuli requires analytical approaches capable of probing molecular signatures. We present a multifunctionalplatform that integrates Surface-Enhanced Raman spectroscopy (SERS),silver nanoparticles,and stiffness-tunable hydrogels to investigate mechanochemical interactions at single-cell and, insome instances, single-molecule resolutions. Silver nanoparticles were synthesized via controlled reduction process to optimize size morphology for strong localized surface plasmon resonance.Characterization confirmed the monodisperse nanoparticles with pronounced optical resonances in the visible range, enabling substantial electromagnetic field enhancement and highly sensitive detection of biomolecular vibrations.Hydrogels with tunable stiffness were fabricated by modulating cross linking density while keeping chemical composition and surface functionalization constant. This design provided a controlled range of elastic moduli to emulate diverse physiological and pathological tissue conditions. Healthy and cancerous colorectal cells were cultured on hydrogels with dispersed SERS nanoparticles, creating a mechanically defined and optically accessible interface for molecular imaging and analysis.Raman spectra acquired from cells on soft versus stiff hydrogels revealed reproducible differences in vibrational modes corresponding to lipids, proteins, and nucleic acids. The high enhancement factors produced by the silver nanoparticles enabled these spectral changes to be detected with exceptional sensitivity, offering insight into how extracellular stiffness modulates intracellular chemical composition. These results suggest that mechanical cues lead to measurable biochemical remodeling at the molecular level, detectable through the enhancedRaman scattering signatures of key cellular components. Combining nanoplasmonics and tunable mechanical substrates, our mechanoplasmonic platform captures real-time, label-free molecular responses of living cells to their physical environment. The ability to detect single-molecule spectral features within biologically relevant contexts demonstrates the analytical strength and versatility of this hybrid system. More broadly, the approach bridges the disciplines of mechanobiology, materials science, and nanophotonics, providing a foundation for future studies on stiffness-mediated cell signaling and potential diagnostic tools that exploit mechanical-biochemical coupling for early detection of disease progression or therapeutic response.