Ultra-low fouling and functionalizable zwitterionic coatings grafted onto SiO2 via a biomimetic adhesive group for sensing and detection in complex media.
ABSTRACT Non-specific protein binding from human plasma and serum has severely hindered the full capabilities of biosensors concerned with cancer biomarker detection. Currently, there is a strong desire for developing new materials which allow for the convenient attachment of an ultra-low fouling and functionalizable surface coating which can be used for highly sensitive and label-free detection of target analytes directly from complex media. In this work, a short 20 min in situ "graft to" protocol using Tris pH 8.5 buffer was developed for zwitterionic carboxybetaine methacrylate (CBMA) polymer conjugates containing the adhesive biomimetic moiety, 3,4-dihydroxy-L-phenylalanine (DOPA), on SiO(2) substrates. Using a surface plasmon resonance (SPR) biosensor, different buffers, pH values, salt concentrations, and temperatures were investigated for determining the "graft to" conditions that yield dense polymer films which both minimize non-specific protein adsorption and maximize antibody immobilization. The optimized surface coatings were shown to be highly protein resistant to 100% human blood plasma and serum. Subsequent antibody functionalized surfaces without any blocking agents enabled the specific detection of the cancer biomarker ALCAM directly from undiluted human serum down to 64 ng/mL. The successful use of this zwitterionic surface coating for detection from complex media on SiO(2) surfaces indicates its potential for broad impacts in the development of implantable medical devices, in vivo diagnostics, and nano-scale biosensors.
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Article: Nanotechnology and biosensors.[show abstract] [hide abstract]
ABSTRACT: Nanotechnology is playing an increasingly important role in the development of biosensors. The sensitivity and performance of biosensors is being improved by using nanomaterials for their construction. The use of these nanomaterials has allowed the introduction of many new signal transduction technologies in biosensors. Because of their submicron dimensions, nanosensors, nanoprobes and other nanosystems have allowed simple and rapid analyses in vivo. Portable instruments capable of analyzing multiple components are becoming available. This work reviews the status of the various nanostructure-based biosensors. Use of the self-assembly techniques and nano-electromechanical systems (NEMS) in biosensors is discussed.Biotechnology Advances 10/2004; 22(7):505-18. · 9.60 Impact Factor
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ABSTRACT: In the present study, we have utilized X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (ELM), and optical waveguide lightmode spectroscopy (OWLS) to examine the surface adsorption and protein resistance behavior of bio-inspired polymers consisting of poly(ethylene glycol) (PEG) conjugated to peptide mimics of mussel adhesive proteins. Peptides containing up to three residues of 3,4-dihydroxyphenylalanine (DOPA), a key component of mussel adhesive proteins, were conjugated to monomethoxy-terminated PEG polymers. These mPEG-DOPA polymers were found to be highly adhesive to TiO2 surfaces, with quantitative XPS analysis providing useful insight into the binding mechanism. Additionally, the antifouling properties of immobilized PEG were reflected in the excellent resistance of mPEG-DOPA-modified TiO2 surfaces to protein adsorption. Measurements of mPEG-DOPA and human serum adsorption were related in terms of ethylene glycol (EG) surface density and serum mass adsorbed and demonstrated a threshold of approximately 15-20 EG/nm2, above which substantially little protein adsorbs. With respect to surface density of adsorbed PEG and the associated nonfouling behavior of the adlayers, strong parallels exist between the nonfouling properties of the surface-bound mPEG-DOPA polymers and PEG polymers immobilized to surfaces using other approaches. Peptide anchors containing three DOPA residues resulted in PEG surface densities higher than those achieved using several existing PEG immobilization strategies, suggesting that peptide mimics of mussel adhesive proteins may be useful for achieving high densities of protein-resistant polymers on surfaces.Langmuir 02/2005; 21(2):640-6. · 4.19 Impact Factor
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ABSTRACT: Nanotechnology is a multidisciplinary field, which covers a vast and diverse array of devices derived from engineering, biology, physics and chemistry. These devices include nanovectors for the targeted delivery of anticancer drugs and imaging contrast agents. Nanowires and nanocantilever arrays are among the leading approaches under development for the early detection of precancerous and malignant lesions from biological fluids. These and other nanodevices can provide essential breakthroughs in the fight against cancer.Nature reviews. Cancer 04/2005; 5(3):161-71. · 35.00 Impact Factor