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ABSTRACT: For potential applications in the isolation and enrichment of circulating tumor cells (CTCs) we have developed gold nanoparticle layers (GNPLs) of different roughness modified with TD05 aptamers (GNPL-APT). In serum-free binary cell mixtures containing Ramos cancer cells and CEM cells, the density of Ramos cells adherent to highly rough GNPL-APT was 19 times that of CEM cells. However, in serum-containing conditions, the specificity of GNPL-APT for Ramos cells was much reduced. To improve Ramos specificity in the presence of serum, the TD05 aptamer was attached to the layers via poly(oligo(ethylene glycol) methacrylate) (POEGMA) as an antifouling spacer (GNPL-POEGMA-APT). In serum-containing environment GNPL-POEGMA-APT showed an enhanced selectivity for Ramos cells, which increased with increasing surface roughness. The results of this study indicate that surfaces combining appropriate chemical composition and micro/nano roughness structures may be useful for cell separation, including the isolation of cancer cells for diagnosis.
ACS Applied Materials & Interfaces 03/2013; · 4.53 Impact Factor
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ABSTRACT: Surface chemical composition and roughness caused by micro/nano-topographical structures are two predominant factors in determining cellular response. A series of gold nanoparticle layers (GNPLs) with increasing surface roughness are prepared by depositing gold nanoparticles onto planar gold films. Glycine-arginine-glycine-aspartic acid-tyrosine (GRGDY) peptide is then conjugated to the surface through poly[oligo(ethylene glycol) methacrylate] polymer brushes as spacers. The pristine micro/nano-roughness structures significantly inhibit L929 cell growth. After modification with POEGMA-GRGDY, however, the micro/nano-structures greatly enhance L929 cell-specific interactions while maintaining superior low-fouling ability compared to planar gold.
Macromolecular Bioscience 08/2012; 12(10):1391-400. · 3.89 Impact Factor
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ABSTRACT: The topography of material surface has important influence on cell behavior and physiological functions. Groove-like pattern
has drawn much attention among various patterns, due to the phenomenon of “contact guidance“ induced by this kind of topography.
This review mainly focuses on “contact guidance“ formation as well as its influence on cell behavior and physiological effects.
The possible mechanisms of “contact guidance” formation were discussed. The research trend and the potential applications
were also suggested.
Chinese Science Bulletin 04/2012; 54(18):3200-3205. · 1.32 Impact Factor
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ABSTRACT: The availability of techniques for the sensitive detection of early stage cancer is crucial for patient survival. Our previous research (Langmuir, 2011, 27, 2155-2158) showed that gold nanoparticle layers (GNPL) used in indirect format ELISA amplified the signal, and gave a lower limit of detection (LOD) compared with commercial ELISA plates. However, due to its intrinsic limitations, indirect ELISA is not suitable for samples of complex composition, such as serum, plasma, etc., thus limiting the clinical performance of this kind of ELISA. In the work reported here, a GNPL-based sandwich format ELISA was developed, which showed superiority in terms of detection limit and sensitivity in the determination of rabbit IgG in buffer. More importantly, experiments using plasma spiked with carcinoembryonic antigen (CEA) as a representative biomarker showed that our GNPL-based ELISA assay amplified the signal and lowered the LOD compared to other assays, including commercialized CEA ELISA kits. This simple and cost-effective GNPL-based sandwich ELISA holds promise in clinical applications.
The Analyst 01/2012; 137(8):1779-84. · 4.23 Impact Factor
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ABSTRACT: Chirality is one of the basic, unique, and most appealing features of biological molecules; however, many intriguing chiral phenomena in biological world remains insufficiently revealed yet. In this research, we fabricated chiral surfaces by assembling natural chiral amino acids-cysteine of opposite configurations (D- and L-) onto gold surfaces, respectively, and investigated the adhesion of the L929 fibroblast on them. No significant differences were observed in the density of adherent cells under serum-free culture condition; while in serum-containing condition, significantly more cells adhered on the L-Cys assembled surfaces. This phenomenon suggested that serum protein might play an important role in mediating the selective adhesion of cells on chiral surfaces. Hence, we adopted both radiolabeling and surface plasmon resonance (SPR) techniques to monitor protein adsorption onto the above surfaces. The results evidently showed more proteins adsorbed onto surfaces assembled with L-Cys. We propose that the difference in protein adsorption on chiral surfaces as demonstrated in this paper might not only shed light on the ensuing investigation of bio-related chirality phenomena, but also provide a novel strategy for the rational design and fabrication of novel biomaterials and bio-related devices based on chiral effects.
Colloids and surfaces. B, Biointerfaces 10/2011; 90:97-101. · 2.60 Impact Factor
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ABSTRACT: Poly(vinylpyrrolidone-b-styrene) (PVP-b-PS) diblock copolymers tethered to glass surfaces were prepared, and the effects on protein adsorption and cellular behavior to the glass and the modified glass surfaces investigated. The PVP-b-PS grafting process was confirmed by water contact angle and XPS measurements. The results obtained for the water contact angles suggest that there are two phases that coexist on the PVP-b-PS block copolymer tethered surface, under aqueous conditions. Although the PVP-b-PS surface possessed, to some extent, a protein resistant property, following introduction of the PS segment to the end of tethered PVP, both fibrinogen and lysozyme adsorption were increased significantly. The PVP-b-PS modified surface, based on Western-blot analysis, appeared to have the greatest amount of surface bound vitronectin, however the conformation of the adsorbed vitronectin may have subsequently been affected by the surface tethered copolymer as was suggested by cell culture results. From these results, we proposed that protein adsorption and cell adhesion can be regulated by tuning the chemical compositions of diblock copolymers tethered to surfaces.
Colloids and surfaces. B, Biointerfaces 09/2010; 79(2):452-9. · 2.60 Impact Factor
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ABSTRACT: Diblock copolymer grafts covalently attached to surfaces have attracted considerable attention because of their special structure and novel properties. In this work, poly(N-isopropylacrylamide)-block-polystyrene (PNIPAAm-b-PS) brushes were prepared via surface-initiated consecutive atom-transfer radical polymerization on initiator-immobilized silicon. Because of the inherent thermosensitivity of PNIPAAm and the hydrophobicity difference between the two blocks, the modified surfaces were responsive to both temperature and solvent. Moreover, the diblock copolymer brushes exhibited both resistance to nonspecific protein adsorption and unique cell interaction properties. They showed strong protein resistance in both phosphate-buffered saline and blood plasma. In particular, fibrinogen adsorption from plasma at either room temperature or body temperature was less than 8 ng/cm(2), suggesting that the surfaces might possess good blood compatibility. In addition, the adhesion and detachment of L929 cells could be "tuned", and the ability to control the detachment of cells thermally was restored by block polymerization of hydrophobic, cell-adhesive PS onto a thicker PNIPAAm layer. In addition to providing a simple and effective design for advanced cell-culture surfaces, these results suggest new biomedical applications for PNIPAAm.
Langmuir 02/2010; 26(11):8582-8. · 4.19 Impact Factor
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Soft Matter. 01/2010; 6:2616-2618.
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ABSTRACT: Cell patterning on substrates has played a significant role in the study of basic biology, cell-based biosensor and tissue engineering. In this report, a cell pattern was prepared on poly(dimethylsiloxane) (PDMS) substrate by vacuum ultraviolet (VUV) lithography. After immobilizing allyl-polyethylene glycol (APEG) onto PDMS, a chemical heterogeneous patterned surface was fabricated by VUV (Xe(2) excimer: 172nm) lithography with copper mesh as a photomask. The UV exposed domains can promote L929 cell adhesion and growth. However, non-exposed regions resist cell attachment because of the repelling property of PEG. Therefore, cell pattern could be achieved without pre-adsorption of cell adhesive species before cell culture.
Colloids and surfaces. B, Biointerfaces 11/2009; 76(1):381-5. · 2.60 Impact Factor
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ABSTRACT: Chemical homogeneous poly(dimethylsiloxane) (PDMS) surface with dot-like protrusion pattern was used to investigate the individual effect of surface microtopography on protein adsorption and subsequent biological responses. Fibrinogen (Fg) and fibronectin (Fn) were chosen as model proteins due to their effect on platelet and cell adhesion, respectively. Fg labeled with (125)I and fluorescein isothiocyanate (FITC) was used to study its adsorption on flat and patterned surfaces. Patterned surface has a 46% increase in the adsorption of Fg when compared with flat surface. However, the surface area of the patterned surface was only 8% larger than that of the flat surface. Therefore, the increase in the surface area was not the only factor responsible for the increase in protein adsorption. Clear fluorescent pattern was visualized on patterned surface, indicating that adsorbed Fg regularly distributed and adsorbed most on the flanks and valleys of the protrusions. Such distribution and local enrichment of Fg presumably caused the specific location of platelets adhered from platelet-rich plasma (PRP) and flowing whole blood (FWB) on patterned surface. Furthermore, the different combination of surface topography and pre-adsorbed Fn could influence the adhesion of L929 cells. The flat surface with pre-adsorbed Fn was the optimum substrate while the virgin patterned surface was the poor substrate in terms of L929 cells spread.
Colloids and surfaces. B, Biointerfaces 04/2009; 71(2):275-81. · 2.60 Impact Factor
