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1.
ACS Appl Mater Interfaces ; 13(35): 41396-41404, 2021 Sep 08.
Article in English | MEDLINE | ID: mdl-32337970

ABSTRACT

Redox-active sites present at large concentrations as part of a solid support or dissolved as molecules in fluid solutions undergo reversible self-exchange electron-transfer reactions. These processes can be monitored using a variety of techniques. Chronoamperometry and cyclic voltammetry are common techniques used to interrogate this behavior for molecules bound to mesoporous thin films of wide-bandgap semiconductors and insulators. In order to use these techniques to obtain accurate values for apparent diffusion coefficients, which are proxies for rate constants for self-exchange electron transfer, it is imperative to take into consideration nonidealities in redox titrations, parasitic currents, and ohmic resistances. Using spectroelectrochemical measurements taken concurrently with measurements of chronoamperometry data, we show that the spectroscopic data is not confounded from effects of parasitic currents or electroinactive dyes. However, we show that the thickness of the thin film over the region that is optically probed by the measurements must be known. When each of these considerations is included in data analyses, calculated apparent diffusion coefficients are, within error, independent of the method used to obtain the data. These considerations help reconcile variations in apparent diffusion coefficients measured using different techniques that have been reported over the past several decades and allow correct analyses to be performed in the future, independent of the method used to obtain the data.

2.
ACS Biomater Sci Eng ; 6(3): 1311-1320, 2020 03 09.
Article in English | MEDLINE | ID: mdl-33455403

ABSTRACT

Stem cells have attracted significant attention due to their regenerative capabilities and their potential for the treatment of disease. Consequently, significant research effort has focused on the development of protein- and polypeptide-based materials as stem cell substrates and scaffolds. Here, we explore the ability of reflectin, a cephalopod structural protein, to support the growth of murine neural stem/progenitor cells (mNSPCs). We observe that the binding, growth, and differentiation of mNSPCs on reflectin films is comparable to that on more established protein-based materials. Moreover, we find that heparin selectively inhibits the adhesion of mNSPCs on reflectin, affording spatial control of cell growth and leading to a >30-fold change in cell density on patterned substrates. The described findings highlight the potential utility of reflectin as a stem cell culture material.


Subject(s)
Cephalopoda , Neural Stem Cells , Animals , Cell Differentiation , Cell Proliferation , Mice , Proteins
3.
Adv Mater ; 30(19): e1704917, 2018 May.
Article in English | MEDLINE | ID: mdl-29656448

ABSTRACT

Cephalopods (e.g., squid, octopuses, and cuttlefish) have long fascinated scientists and the general public alike due to their complex behavioral characteristics and remarkable camouflage abilities. As such, these animals are explored as model systems in neuroscience and represent a well-known commercial resource. Herein, selected literature examples related to the electrical properties of cephalopod-derived biopolymers (eumelanins, chitosans, and reflectins) and to the use of these materials in voltage-gated devices (i.e., transistors) are highlighted. Moreover, some potential future directions and challenges in this area are described, with the aim of inspiring additional research effort on ionic and protonic transistors from cephalopod-derived biopolymers.

4.
Phys Biol ; 15(3): 031002, 2018 03 09.
Article in English | MEDLINE | ID: mdl-29205173

ABSTRACT

This roadmap outlines the role semiconductor-based materials play in understanding the complex biophysical dynamics at multiple length scales, as well as the design and implementation of next-generation electronic, optoelectronic, and mechanical devices for biointerfaces. The roadmap emphasizes the advantages of semiconductor building blocks in interfacing, monitoring, and manipulating the activity of biological components, and discusses the possibility of using active semiconductor-cell interfaces for discovering new signaling processes in the biological world.


Subject(s)
Cell Communication/physiology , Polymers/chemistry , Semiconductors , Surface Properties
5.
Adv Mater ; 28(38): 8405-8412, 2016 Oct.
Article in English | MEDLINE | ID: mdl-27454809

ABSTRACT

Films from the cephalopod protein reflectin demonstrate multifaceted functionality as infrared camouflage coatings, proton transport media, and substrates for growth of neural stem cells. A detailed study of the in vitro formation, structural characteristics, and stimulus response of such films is presented. The reported observations hold implications for the design and development of advanced cephalopod-inspired functional materials.


Subject(s)
Cephalopoda , Animals , Neural Stem Cells , Proteins , Protons
6.
ACS Appl Mater Interfaces ; 8(1): 278-84, 2016 Jan 13.
Article in English | MEDLINE | ID: mdl-26703760

ABSTRACT

Cephalopods possess remarkable camouflage capabilities, which are enabled by their complex skin structure and sophisticated nervous system. Such unique characteristics have in turn inspired the design of novel functional materials and devices. Within this context, recent studies have focused on investigating the self-assembly, optical, and electrical properties of reflectin, a protein that plays a key role in cephalopod structural coloration. Herein, we report the discovery that reflectin constitutes an effective material for the growth of human neural stem/progenitor cells. Our findings may hold relevance both for understanding cephalopod embryogenesis and for developing improved protein-based bioelectronic devices.


Subject(s)
Biocompatible Materials/pharmacology , Neural Stem Cells/cytology , Proteins/pharmacology , Animals , Astrocytes/cytology , Astrocytes/drug effects , Cell Differentiation/drug effects , Cell Line , Cell Proliferation/drug effects , Decapodiformes/chemistry , Humans , Microscopy, Fluorescence , Neural Stem Cells/drug effects , Neurons/cytology , Neurons/drug effects
7.
Adv Mater ; 26(29): 4986-90, 2014 Aug 06.
Article in English | MEDLINE | ID: mdl-24789251

ABSTRACT

Two-terminal protonic devices with PdHx proton conducting contacts and a Nafion channel achieve 25 ms spiking, short term depression, and low-energy memory switching.


Subject(s)
Biomimetics/instrumentation , Protons , Synapses , Time Factors
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