Cellular prostheses: functional abiotic nanosystems to probe, manipulate, and endow function in live cells

Schematic showing PV-FAN modified cell membrane. Two potential positions of PV-FANs are shown: (A) Transmembrane embedment (maximum excitation efficiency) and (B) attached to a membrane receptor through appropriate ligand. V_ECF and V_Cyt are the potential of the ECF (extracellular fluid) and the cytosolic region. Δρ_FAN is the charge density within the excited PV-FAN. Δρ_Ind is the induced charge density in the surrounding medium.

A zero-order equivalent circuit model of the cell membrane, PV-FAN, and their environment, together as a system. ε_M represents the equivalent electromotive potential directed from cytosol to ECF due to the ionic gradient across the membrane.

Plots of membrane potential modulation (ΔV_M) as a function of time for illustrative values of relevant parameters (k_d = 100, 300, 1000 sec⁻¹ and k_ex = 200 sec⁻¹, k_M = 100 sec⁻¹, n₀ = 2 × 10³ μm⁻², c_M = 1 μF/cm²).

A surface plot showing the dependence of ΔV_M (max) on k_ex/k_M and k_d/ k_M. Note ΔV_M (max) scales linearly with en₀/c_M.

Surface plots showing the minimum required photovoltaic functional abiotic nanosystem density (n₀) as a function of excitation and decay rate (k_ex and k_d) to allow action potential firing under the following three conditions bracketing typical neuronal cell characteristics. (A) Most relaxed situation: k_M = 10 sec⁻¹ and ΔV_th = 10 mV; (B) intermediate situation, close to retinal ganglion cells: k_M = 100 sec⁻¹, ΔV_th = 15 mV; (C) most restrained situation: k_M = 1000 sec⁻¹ and ΔV_th = 20 mV.

(A) Schematic showing the implementation of photovoltaic functional abiotic nanosystem using a heterojunction. Material A or B represent either semiconductor-metal (S-M) or semiconductor-semiconductor (S-S) combination. (B) Schematic band diagram of a S-M heterojunction. (C) Schematic band diagram of a type II S-S heterojunction. E_C and E_V represent the energy of the conduction and valence band edges of the semiconductors. E_f is the Fermi energy of the semiconductor and the metal. Φ_n is the height of the Schottky barrier.

(A) Schematic showing the implementation of photovoltaic functional abiotic nanosystem using a molecular donor-acceptor pair connected through a bridge molecule. (B) Schematic energy levels of donor-acceptor pair.