We have developed a purely protein-based multilayered semiconducting 3D material using iron-storage protein ferritin. It is electronically homogeneous; capable of long range electron transport having a long exciton radius, and shows z-confinement.
We trap absorbing micro-particles in air by photophoretic forces generated using a single loosely focused Gaussian trapping beam. We measure a component of the radial Brownian motion of a trapped particle cluster and determine the power spectral density, mean squared displacement, and normalized position and velocity autocorrelation functions in order to characterize the photophoretic body force in a quantitative fashion for the first time. The trapped particles also undergo spontaneous rotation due to the action of this force. This is evident from the spectral density that displays clear peaks at the rotation and the particles' inertial resonance frequencies. We fit the spectral density to the well-known analytical function derived from the Langevin equation, measure the resonance and rotation frequencies and determine values for particle mass that we verify at different trapping laser powers with reasonable accuracy.
The polarized low-temperature absorption spectrum, emission spectrum, and excitation spectrum of benzil and benzil-doped stilbene crystals have been recorded. It has been found that the 3800 A (n--,r*) band system of benzil is split by the weak interaction between the two halves of the molecule. The excitation spectrum reveals the presence of a S->T transition hidden underneath the S->S transition. The crystal spectrum of benzil-doped stilbene is different from the benzil spectrum. The new sharp band at 4850 A has been interpreted in terms of a trans-planar configuration of benzil. A weak ( ... *->n) fluorescence has been detected in this crystal.
Silicon is a solid-state semiconducting material that has long been recognized as a technologically useful one, especially in electronics industry. However, its application in the next-generation metalloprotein-based electronics approaches has been limited. In this work, the applicability of silicon as a solid support for anchoring the iron-storage protein ferritin, which has a semiconducting iron nanocore, and probing electron transport via the ferritin molecules trapped between silicon substrate and a conductive scanning probe has been investigated. Ferritin protein is an attractive bioelectronic material because its size (X-ray crystallographic diameter ∼12 nm) should allow it to fit well in the larger tunnel gaps (>5 nm), fabrication of which is relatively more established, than the smaller ones. The electron transport events occurring through the ferritin molecules that are covalently anchored onto the MPTMS-modified silicon surface could be detected at the molecular level by current-sensing atomic force spectroscopy (CSAFS). Importantly, the distinct electronic signatures of the metal types (i.e., Fe, Mn, Ni, and Au) within the ferritin nanocore could be distinguished from each other using the transport band gap analyses. The CSAFS measurements on holoferritin, apoferritin, and the metal core reconstituted ferritins reveal that some of these ferritins behave like n-type semiconductors, while the others behave as p-type semiconductors. The band gaps for the different ferritins are found to be within 0.8 to 2.6 eV, a range that is valid for the standard semiconductor technology (e.g., diodes based on p-n junction). The present work indicates effective on-silico integration of the ferritin protein, as it remains functionally viable after silicon binding and its electron transport activities can be detected. Potential use of the ferritin-silicon nanohybrids may therefore be envisaged in applications other than bioelectronics, too, as ferritin is a versatile nanocore-containing biomaterial (for storage/transport of metals and drugs) and silicon can be a versatile nanoscale solid support (for its biocompatible nature).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.