This study shows that coupling to designed plasmonic nanoparticles can modulate the electrophysiological function of proteins in living mammalian cells. Nanostar-shaped particles, that are robust to biological noise, are designed to enable near-field-coupling to plasma membrane-localized mutated Archaerhodopsin proteins in live cells. The coupled rhodopsins exhibit enhanced fluorescence and an increased response speed to membrane voltage. Incorporating this plasmonic enhancement into a Markov chain photocycle model of the Archaerhodopsin mutant QuasAr6a, shows an increased fluorescence emission rate and manipulation of the protein dynamics through a combination of photocycle transition rate enhancements. The results show an improvement in fluorescence and voltage-response dynamics of the functional QuasAr6a Archaerhodopsin mutant, beyond what has been achievable through genetic engineering. This opens up possibilities for engineering the biological functionality of proteins through plasmonics: manipulating protein photocycles could improve light sensitivity, change optogenetic applications, and lead to fluorescent biosensors with enhanced dynamics.

This dissertation addresses one of the longstanding challenges in modern biomedical science: how to rapidly and precisely control the function of proteins in living cells. Traditionally, scientists have relied on genetic modifications to tweak proteins and improve their performance, but this approach has some inherent limitations in speed and adaptability. Instead, the work presented here explores an alternative strategy: manipulating the environment in which a protein operates to alter its behavior, rather than rewriting its genetic code. The study revolves around a genetically encoded voltage indicator known as QuasAr6a, a protein used to optically monitor electrical activity in cells, neurons in particular....

Plasmonic enhancement of fluorescence has been challenging in in vivo imaging applications. We present a study demonstrating the plasmonic enhancement of fluorescent membrane proteins within their native physiological environment using tailored metallic nanoparticles. This work highlights two schemes to influence the distance between the emitting dipoles and the enhancing nanoparticles, namely the addition of nanoparticles in the buffer solution and the incorporation in the polymer matrix at the bottom of the cells. Incorporating biological structures native to the cellular environment offers opportunities for the optimization of in vivo fluorescence imaging methods and the detection of membrane proteins.

Localized surface plasmons (LSPs) in metal particles are used in medical, chemical, physical, and biological sensing applications. In this paper, we revisit the classical description of LSPs. We use the Drude model and the Quasi-Static approximation to describe the plasmon resonances in terms of the material and the size of the particles embedded in a dielectric host. We then incorporate the Clausius-Mossotti relation to include shape effects in the classical description. Finally, we incorporate surface damping and retardation effects to arrive at a unified, classical description providing an intuitive and realistic model of plasmonic resonances in metal particles.

Cultured meat is a lab grown product that aims to tackle the cravings of omnivores who struggle to switch to a plant-based diet, while still being friendly to animals and the environment. Possibly, in time, the curiosity to apply this technology towards human meat production will emerge. However, when presented with the thought of eating cultured human meat potential consumers’ reaction greatly varies from pure disgust to indifference to excitement. This instinctive response indicates a lack of preformed judgements towards the topic. Without a clear vision on the possibility of cultured human meat, scattered and uncertain regulations will fail to uphold paramount moral values. The risk is that we would either dig into this option out of excitement, or ban it without convincing motivations. The ethical theories of deontology and consequentialism can be followed to investigate this divisive issue. With an evaluation based on disgust I argue that the deontological perspective is mostly concerned with values of identity and humanness, while with a chain-reaction reasoning I argue that consequentialism would be concerned with health safety, privacy and equality. I conclude that cultured human meat is not acceptable.