Nanoparticle Bioconjugate for Membrane Potential Imaging

The patent changes the fundamental parameters of the sensor system by replacing traditional fluorophore-based sensors with a nanoparticle-based electron donor-acceptor system. This involves changing the material composition (nanoparticles instead of organic dyes), the detection mechanism (electron transfer quenching instead of fluorescence emission), and the structural organization (modular peptide-nanoparticle conjugates). These parameter changes simultaneously improve photostability (nanoparticles are inherently more photostable than organic dyes) and reduce cytotoxicity (the modular design allows for biocompatible surface functionalization and controlled electron transfer that minimizes cellular damage).

The patent employs composite materials by creating a hybrid system consisting of a photoluminescent nanoparticle core conjugated to a modular peptide structure with electron acceptor moieties. This composite architecture combines the photostability and optical properties of inorganic nanoparticles with the biological compatibility and membrane-targeting capabilities of peptide structures. The electron acceptor component (such as fullerene or other electron-deficient molecules) is integrated into the peptide-nanoparticle conjugate, creating a multifunctional composite material that achieves both high photostability and low cytotoxicity while enabling membrane potential sensing.

The patent fundamentally changes the photophysical parameters of the sensing system by replacing traditional fluorophores with a nanoparticle-based electron donor-acceptor system. The nanoparticle core (such as quantum dots or upconversion nanoparticles) exhibits superior photostability compared to organic fluorophores, enabling prolonged imaging durations without signal degradation. The electron transfer quenching mechanism provides a stable optical readout that does not suffer from photobleaching, allowing imaging experiments to continue for extended periods while maintaining signal reliability.

The patent substitutes the fluorescence emission mechanism with an electron transfer quenching mechanism. Instead of relying on fluorophore excitation and emission, which are prone to photobleaching, the system uses photoexcited electrons in the nanoparticle that can transfer to the electron acceptor moiety. This electron transfer process is not subject to photobleaching and provides a stable, long-lasting optical signal that enables prolonged imaging durations while maintaining high reliability.

The patent applies segmentation by dividing the sensor construct into distinct modular components: a photoluminescent nanoparticle core, a peptide linker with membrane-targeting sequences, and an electron acceptor moiety. Each component can be independently synthesized, characterized, and optimized using established protocols. The modular peptide structure contains separate functional domains (membrane insertion motifs, nanoparticle binding sequences, electron acceptor attachment sites) that can be independently designed and assembled. This segmented approach simplifies manufacturing by allowing parallel synthesis of components and reducing the complexity of the overall construction process.

The patent employs universality through the design of a modular peptide structure that can be adapted to different nanoparticle types and electron acceptor moieties. The peptide contains universal functional elements (such as histidine tags for nanoparticle binding, amphipathic helices for membrane insertion) that can be combined with various sensing components. This universal modular framework allows the same basic construct design to be applied across different nanoparticle platforms (quantum dots, upconversion nanoparticles, etc.) and electron acceptor types, thereby simplifying manufacturing by reducing the need for de novo synthesis for each variant while maintaining full sensor functionality.