Genetically programmable thermoresponsive plasmonic gold/silk-elastin protein core/shell nanoparticles

Area of Science:

• Biomolecular Engineering
• Nanotechnology
• Materials Science

Background:

• Developing molecular photonic/electronic systems requires controlled integration of functional molecular building blocks.
• Biosynthesis offers a unique approach for synthesizing environmental factor-responsive chimeric proteins.
• Silk-elastin-like protein polymers (SELPs) provide a modular platform for such applications.

Purpose of the Study:

• To genetically engineer SELPs for facile tuning of dynamic thermal response in plasmonic nanoparticles.
• To synthesize a new family of SELPs (S4E8Gs) with tunable molecular weight and controlled self-assembly.
• To investigate thermally reversible nanoparticle aggregation and its effect on plasmon coupling.

Main Methods:

• Recombinant DNA techniques were used to synthesize S4E8Gs SELPs with specific amino acid repeats.
• Site-specific glycine mutation programmed temperature-reversible conformational switching (50-60 °C).
• Characterization involved variable-temperature proton NMR, circular dichroism (CD) spectroscopy, transmission electron microscopy (TEM), dynamic light scattering (DLS), and UV-vis spectroscopy.

Main Results:

• Genetically engineered SELPs demonstrated tunable thermal response and controlled nanoparticle aggregation/disaggregation.
• The size and pattern of Au-SELPs nanoparticle assembly were regulated by the silk blocks.
• Variable-temperature UV-vis spectroscopy and finite-difference time-domain (FDTD) simulations showed thermally reversible interparticle plasmon coupling dependent on shell dimensions.

Conclusions:

• Genetic engineering of SELPs enables precise control over the thermal response and self-assembly of plasmonic nanoparticles.
• This approach facilitates the design and synthesis of responsive nanostructures by tuning SELP properties.
• The findings provide insights for developing advanced molecular photonic/electronic systems with tunable energy conversion capabilities.