4 research outputs found
Nonfouling Property of Zwitterionic Cysteine Surface
Applications of implantable bioelectronics
for analytical and curative
purposes are currently limited by their poor long-term biofunctionality
in physiological media and nonspecific interactions with biomolecules.
In an attempt to prolong in vivo functionality, recent advances in
surface modifications have demonstrated that zwitterionic coatings
can rival the performance of conventional polyÂ(ethylene glycol) polymers
in reducing nonspecific protein fouling. Herein, we report the fabrication
of a very thin layer of nonfouling zwitterionic cysteine surface capable
of protecting implantable bioelectronics from nonspecific adsorption
of plasma proteins. This work is the first of its kind to fabricate,
through solution chemistry, a cysteine surface exhibiting zwitterionic
state as high as 88% and to demonstrate antibiofouling under the exposure
of bovine serum albumin (BSA) and human serum. The fabricated surface
utilized a minimal amount of gold substrate, approximately 10 nm,
and an extremely thin antifouling layer at 1.14 nm verified by ellipsometry.
X-ray photoelectron spectroscopy assessment of the nitrogen (N<sub>1s</sub>) and carbon (C<sub>1s</sub>) spectra conclude that 87.8%
of the fabricated cysteine surface is zwitterionic, 2.5% is positively
charged, and 9.6% is noncharged. Antibiofouling performance of the
cysteine surface is quantitatively determined by bicinchoninic acid
(BCA) protein assay as well as qualitatively confirmed using scanning
electron spectroscopy. Cysteine surfaces demonstrated a BSA fouling
of 3.9 ± 4.84% μg/cm<sup>2</sup>, which is 93.6% and 98.5%
lower than stainless steel and gold surfaces, respectively. Surface
plasmon resonance imaging analysis returned similar results and suggest
that a thinner cysteine coating will enhance performance. Scanning
electron microscopy confirmed the results of BCA assay and suggested
that the cysteine surface demonstrated a 69% reduction to serum fouling.
The results reported in this paper demonstrate that it is possible
to achieve a highly zwitterionic surface through solution chemistry
on a macroscopic level that is capable of improving biocompatibility
of long-term implantable bioelectronics
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Example of the Type of Data Available from the Online Database (http://www.bruinfly.ucla.edu)
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