PLGA Surface Research Articles

Adhesion Assays of Endothelial Cells on Nanopatterned Surfaces within a Microfluidic Channel

We present a simple analytical method to measure adhesion of human umbilical vein endothelial cells (HUVECs) and calf pulmonary artery endothelial cells (CPAEs) using nanopatterned, biodegradable poly(lactic-co-glycolic acid) (PLGA) surfaces for potential applications to artificial tissue-engineered blood vessel. Various nanostructured PLGA surfaces (350 nm wide ridges/350 nm grooves, 350 nm ridges/700 nm grooves, 350 nm ridges/1750 nm grooves, 700 nm ridges/350 nm grooves, 1050 nm ridges/350 nm grooves, 1750 nm ridges/350 nm grooves) and flat (unpatterned) surfaces were fabricated on the bottom of polydimethylsiloxane (PDMS) microfluidic channel of 2 mm width and 60 microm height by using thermal imprinting and irreversible channel bonding. To measure adhesion strength of HUVECs and CPAEs, the cells were exposed to a range of shear stress (12, 40, and 80 dyn/cm(2)) within the channels for 20 min after a preculture for 3 days and the remaining cells were counted under each condition. The highest adhesion strength was found on the surface of 700 nm wide ridges, 350 nm wide grooves for both cell types. The enhanced adhesion on nanopatterned surfaces can be attributed to two aspects: (i) contact guidance along the line direction and (ii) clustered focal adhesions. In particular, the contact guidance induced cell alignment along the line directions, which in turn lowers wall shear stress applied to the cell surface, as supported by a simple hydrodynamic model based on cell morphology.

Modification of Poly(lactic/glycolic acid) Surface by Chemical Attachment of Poly(ethylene glycol)

Biodegradable polyesters such poly(lactic acid) and poly(lactic/glycolic acid) (PLGA) copolymers are preferred biomaterials and used among others as drug delivery systems, although their surface hydrophobicity limits their application. In this work, chemical modification of the PLGA surface was developed by coupling of either linear or starlike poly(ethylene glycol) (PEG) molecules via chemical bonds to the PLGA surface following amino functionalization as a first step to improve its biocompatibility. The chemical attachment was followed by detailed X-ray photoelectron spectroscopy (XPS) studies. It was shown that substantial modification can be achieved by linear PEG, but even higher surface coverage with hydrophilic groups can be obtained when the six-armed PEG is applied with the additional advantage of possible further functionalization via free amino groups available on the surface of the latter. As a final goal, a significant increase of water wettability together with reduced protein adsorption was achieved on PEG-coupled PLGA surfaces.

Conformational behavior of fibrinogen on topographically modified polymer surfaces

The influence of topographical surface features at the submicron scale on the structural changes in the surface-adsorbed fibrinogen was investigated on poly(lactic-co-glycolic-acid) (PLGA) films. Attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) was employed in this study for the induced conformational change of fibrinogen over various adsorption times, while the adsorption kinetics of fibrinogen was quantified by the enzyme linked immunosorbent assay (ELISA). When a PLGA surface is modified topographically, the adsorbed fibrinogen undergoes less conformational change when compared to adsorption on the pristine PLGA surface. The extent of conformational change is related to platelet adhesion. Reduced thrombogenicity was demonstrated by the higher ratios of alpha-helix to beta-turn and beta-sheet to beta-turn structures on the topographic PLGA film, which suggests that topographical manipulation of surfaces is a viable approach to influence the thrombogenicity of surfaces.

Biodegradable nanoparticles modified by branched polyethylenimine for plasmid DNA delivery

The main objective of this work is to build a comparative account of two PLGA nanoparticle (NP)-based gene delivery systems namely, plasmid DNA (pDNA) encapsulated PLGA NPs (PLGA-E) and surface adsorbed pDNA on PLGA-BPEI NPs (PLGA-BPEI), with respect to the extent of internalization and intracellular release of pDNA. Several formulations have also been evaluated systematically for determination of the optimal transfection efficiency. The zeta-potential, particle size measurements and DNase I protection assay established the importance of the BPEI chain length in regulating the effective loading and condensation of pDNA with PLGA-BPEI NPs and pDNA protection ability of PLGA-BPEI NPs. The colloidal stability of these formulations was also investigated as a function of serum concentration. The in vitro release of pDNA from both kind of formulations was studied at pH 7.4 and pH 5.0 by comparing the kinetics of pH-triggered release of pDNA from PLGA-BPEI-25K(5) and PLGA-E. In vitro time-dependent gene transfection efficiencies were studied in presence as well as in absence of serum for NIH3T3 and HEK293 cells. The cell viability and intracellular localization were also investigated using MTT assay and confocal microscopy study, respectively.

Coating of hydrophobins on three-dimensional electrospun poly(lactic-co-glycolic acid) scaffolds for cell adhesion

Surface modification with hydrophobins is very important for cell adhesion in its applications in biosensor fabrication. In this study, we modified the surface of three-dimensional electrospun poly(lactide-co-glycolide) (PLGA) scaffolds with hydrophobin HFBI and collagen, and investigated its applications for cell adhesion. We found that HFBI could not only improve the hydrophilicity of the three-dimensional electrospun PLGA scaffolds but also endow the electrospun PLGA scaffolds with water permeability. This permeability should be attributed to both the hydrophilicity of the modified PLGA surface and the large positive capillary effect induced by the microstructures. Further experiment indicated that HFBI modification could improve collagen immobilization on the electrospun PLGA scaffolds and the HFBI/collagen modified electrospun PLGA scaffolds showed higher efficiency in promoting cell adhesion than the native PLGA scaffolds. This finding should be of potential application in biosensor device fabrication.

Patterning of neural stem cells on poly(lactic-co-glycolic acid) film modified by hydrophobin

Patterning of neural stem cells (NSCs) is of great importance for its potential applications in the therapy of nerve injuries. Due to the critical requirements and the great difficulty in NSCs cultivation, developing new methods for NSCs patterning is very challenging and has progressed slowly in recent years. In this study, we reported a new method for patterning NSCs on a hydrophobin II (HFBI) modified poly(lactic-co-glycolic acid) (PLGA) film by using microcontact printing (μCP) technique. HFBI modification converted the PLGA surface from hydrophobic to hydrophilic, which should facilitate the absorption of serum on it. Serum was transferred onto the modified PLGA film by microcontact printing (μCP) to promote NSCs adhesion on the PLGA surface. Since the serum-coated PLGA surface promoted NSCs adhesion and the serum-free PLGA surface inhibited NSCs adhesion, micro-patterns of NSCs were obtained by directly culturing NSCs on the PLGA surface patterned with serum. This method allows the precise control of NSCs adhesion on the PLGA film without using the conventional cell-repellent species, which is anticipated to make great contribution in the fields of therapy of nerve injuries.

Surface modification of porous scaffolds with nanothick collagen layer by centrifugation and freeze‐drying

Three-dimensional (3D) porous scaffolds constructed from biodegradable synthetic polymers are frequently used in tissue engineering. Their surfaces are hydrophobic and require treatment to be changed to hydrophilic before use in cell culture. We developed a novel surface modification for 3D porous scaffolds made of synthetic polymers by coating the surfaces of the pores with a nanothick collagen layer. First, a collagen aqueous solution was introduced under reduced pressure to fully fill the pores of the PLGA sponges. The collagen-containing sponges were then centrifuged to remove any excess collagen solution. Finally, the sponges were freeze-dried to form a thin collagen layer. Scanning electron microscopy observation and water absorption tests demonstrated that the excess collagen was removed; the effect of modification was evident when the collagen-containing sponges were centrifuged at high centrifugal acceleration. Scanning probe microscopy analysis demonstrated the formation of a nanometer-thick collagen layer on the PLGA surface. The collagen-coated PLGA sponges facilitated cell seeding and spatial distribution. The method will be useful for the surface modification of 3D porous scaffolds.

Cyto‐ and hemocompatibility of a biodegradable 3D‐scaffold material designed for medical applications

In this study, the polyester urethane Degrapol (DP) was explored for medical applications. Electrospun DP-fiber fleeces were characterized with regard to fiber morphology, swelling, and interconnectivity of interfiber spaces. Moreover, DP was assayed for cell proliferation and hemocompatibility being a prerequisite to any further in vivo application. It was shown that DP-fiber fleeces produced at different humidity while spinning affects interconnectivity of interfiber spaces, such that the higher the humidity the looser the resulting fiber fleeces. When the spinning target was cooled with dry ice, the resulting DP-fibers remained less fused to each other. However, permeability for fluorescent beads was not significantly increased. Fibroblast adhesion and proliferation occurred in a comparable manner on native as well as on fibronectin or collagen I adsorbed DP-fiber fleeces. On DP-surfaces fibroblasts proliferated equally well as compared with glass or PLGA surfaces or DP-surfaces adsorbed with fibronectin or collagen I. In contrast, human umbilical vein endothelial cells proliferated only after adsorption of DP-surfaces with fibronectin or collagen I, indicating that different cell types respond differently to DP-surfaces. Furthermore, hemocompatibility of DP-surfaces was found to be similar or better to PLGA or stainless steel, both medically used materials. These experiments indicate that DP-fiber fleeces or surfaces might be useful for tissue engineering.

Poly (lactic-co-glycolic acid) as a controlled release delivery device

Poly (lactic-co-glycolic acid) (PLGA) is a biodegradable polymer used to make resorbable sutures, and is also used in other applications in tissue engineering. Being an artificial polymer, its degradation rate can be tailored to suit its application. It can be easily moulded into structures with suitable mechanical strength and degrades into relatively harmless products in the body. Its adjustable degradation rate also makes it a potentially excellent controlled release delivery device. However, the functionalization of PLGA with bioactive molecules usually requires extensive chemical modification. Chemical modification may compromise the mechanical strength of PLGA and inactivate the bioactive molecules. In this paper, a study is done to investigate the coating of an angiogenic factor on unmodified PLGA suture substrates for the differentiation of human mesenchymal stem cells (hMSC) into endothelial cells (EC). The results show that the method used to anchor vascular endothelial growth factor (VEGF) onto the PLGA surface can enable the gradual release of VEGF from the substrate into solution to induce the differentiation of hMSCs into ECs. Thus, this method can potentially be used to coat PLGA materials like sutures, meshes and scaffolds, rendering them functional as effective controlled release delivery devices for a wide range of bioactive molecules.

Modeling the adhesion of human embryonic stem cells to poly(lactic‐co‐glycolic acid) surfaces in a 3D environment

Human embryonic stem cells (hESCs) have previously been cultured on three dimensional (3D) biodegradable polymer scaffolds. Although complex structures were formed from the hESCs, very little is known about the mechanism of adhesion of these cells to the surfaces of the scaffolds. In this study, we achieved the efficient adhesion of pluripotent hESCs to 3D poly(lactic-co-glycolic acid) (PLGA) scaffolds based on our data from a novel two dimensional (2D) model that imitates the surface properties of the scaffolds. In the 2D model, single cell preparations of pluripotent hESCs adhered efficiently and predominantly to PLGA surfaces coated with laminin in comparison to collagen I, collagen IV, or fibronectin-coated surfaces. Flow cytometry analysis revealed that almost all of the pluripotent single cells expressed the integrin alpha 6, with a small percentage also expressing alpha 3ss1, which facilitates adhesion to laminin. This data was then translated into the 3D environment, with the efficient binding of single pluripotent hESCs to PLGA scaffolds coated with laminin. The utility of this system was shown by the directed differentiation of single hESCs seeded within laminin-coated scaffolds toward the endoderm lineage.

Extracellular Matrix Remodeling, Integrin Expression, and Downstream Signaling Pathways Influence the Osteogenic Differentiation of Mesenchymal Stem Cells on Poly(Lactide-Co-Glycolide) Substrates

The possibility of using multipotent adult bone marrow-derived mesenchymal stem cells (MSCs) for tissue-engineering applications hinges on the ability to predictably control their differentiation. Previously, we showed the osteogenic potential of adult bone marrow-derived MSCs cultured on thin films of poly(lactide-co-glycolide) (PLGA) depends in part on the identity of extracellular matrix (ECM) ligands initially deposited onto the material from serum in the culture medium. Here we have addressed the hypothesis that remodeling of the PLGA surface via the de novo synthesis of ECM proteins by the MSCs may also play an important role in governing their osteogenic differentiation. Supporting this hypothesis, increasing amounts of fibronectin and type-I collagen were synthesized and deposited onto thin-film PLGA substrates, whereas vitronectin levels diminished over a 28-day time course. Integrin expression profiles changed accordingly, with higher levels of alpha2beta1 and alpha5beta1 than alphavbeta3 at three different time points. The mitogen-activated protein kinase (MAPK) and phosphatidyl inositol-3-kinase (PI3K) pathways were also activated in MSCs cultured on these substrates, and their inhibition significantly inhibited osteogenic differentiation as assessed according to alkaline phosphatase activity and mineral deposition. These data indicate that initial ECM deposition, subsequent matrix remodeling, and corresponding integrin expression profiles influence osteogenesis in MSCs cultured on PLGA in part by engaging MAPK and PI3K signaling pathways. Understanding the mechanisms by which stem cells respond to different polymers will be critical in their eventual therapeutic use.

Decreased lung carcinoma cell density on select polymer nanometer surface features for lung replacement therapies

AbstractPLGA (poly-lactic-co-glycolic acid) has been widely used as a biomaterial in regenerative medicine due to its biocompatibility and biodegradability properties. Previous studies have shown that cells (such as bladder smooth muscle cells, chondrocytes, osteoblasts, and vascular smooth muscle cells) respond differently to nano-structured PLGA surfaces (such as those with surface features less than 100 nm in at least one dimension) compared to nano-smooth surfaces. The purpose of the present in vitro research was to prepare PLGA films with various nanometer surface features and determine, for the first time, whether lung cancer epithelial cells respond differently to such topographies. Poly(dimethylsiloxane) (PDMS) molds prepared by placing PDMS onto various polystyrene monolayers and two solution evaporation methods were used to create nanometer surface features on PLGA. The intended spherical surface nano-topographies on PLGA with RMS values of 2.23, 5.03, 5.42 and 36.90 nm were formed, while PLGA surfaces with RMS values of 0.62 and 2.23 nm were obtained by different solution evaporation methods. Most importantly, lung cancer epithelial cells adhered less on the PLGA surfaces with an RMS value of 0.62, 2.23 and 5.42 nm after 4 hours of culture compared to any other PLGA surface created here. After three days, PLGA surfaces with an RMS value of 0.62 nm had much lower cell density than any other sample. In this manner, PLGA with specific nanometer surface features may inhibit lung cancer cell density which may provide for an important biomaterial for the treatment of lung cancer for a wide range of applications (from drug delivery to regenerative medicine).

Poly(Lactic-co-Glycolic) Acid as a Carrier for Imaging Contrast Agents

With the broadening field of nanomedicine poised for future molecular level therapeutics, nano- and microparticles intended for the augmentation of either single- or multimodal imaging are created with PLGA as the chief constituent and carrier. Emulsion techniques were used to encapsulate hydrophilic and hydrophobic imaging contrast agents in PLGA particles. The imaging contrast properties of these PLGA particles were further enhanced by reducing silver onto the PLGA surface, creating a silver cage around the polymeric core. The MRI contrast agent Gd-DTPA and the exogenous dye rhodamine 6G were both encapsulated in PLGA and shown to enhance MR and fluorescence contrast, respectively. The silver nanocage built around PLGA nanoparticles exhibited strong near infrared light absorbance properties, making it a suitable contrast agent for optical imaging strategies such as photoacoustic imaging. The biodegradable polymer PLGA is an extremely versatile nano- and micro-carrier for several imaging contrast agents with the possibility of targeting diseased states at a molecular level.

Nanometer polymer surface features: the influence on surface energy, protein adsorptionand endothelial cell adhesion

Current small diameter (<5 mm) synthetic vascular graft materials exhibit poor long-term patency due tothrombosis and intimal hyperplasia. Tissue engineered solutions have yielded functionalvascular tissue, but some require an eight-week in vitro culture period prior toimplantation—too long for immediate clinical bedside applications. Previous in vitrostudies have shown that nanostructured poly(lactic-co-glycolic acid) (PLGA)surfaces elevated endothelial cell adhesion, proliferation, and extracellular matrixsynthesis when compared to nanosmooth surfaces. Nonetheless, these studies failedto address the importance of lateral and vertical surface feature dimensionalitycoupled with surface free energy; nor did such studies elicit an optimum specificsurface feature size for promoting endothelial cell adhesion. In this study, a series ofhighly ordered nanometer to submicron structured PLGA surfaces of identicalchemistry were created using a technique employing polystyrene nanobeads andpoly(dimethylsiloxane) (PDMS) molds. Results demonstrated increased endothelial celladhesion on PLGA surfaces with vertical surface features of size less than 18.87 nmbut greater than 0 nm due to increased surface energy and subsequently protein(fibronectin and collagen type IV) adsorption. Furthermore, this study providedevidence that the vertical dimension of nanometer surface features, rather than thelateral dimension, is largely responsible for these increases. In this manner, thisstudy provides key design parameters that may promote vascular graft efficacy.

Effect of cell‐adhesive‐molecule‐coated poly(lactide‐ co‐glycolide) film on the cellular behaviors of olfactory ensheathing cells and Schwann cells

AbstractThe surface properties of polymeric devices that are used to repair damaged nervous tissue are a point to be considered for axon regeneration in the nervous system. In this study, we investigated the interaction of olfactory ensheathing cells (OECs) and Schwann cells (SCs) with poly(lactide‐co‐glycolide) (PLGA) film surfaces coated with various cell‐adhesive molecules. We used cell adhesives such as fibronectin, fibrinogen, laminin, vitronectin, poly(d‐lysine), and poly(l‐lysine) to coat PLGA film surfaces. We cultured 1 × 104 cells/cm2 (OECs or SCs) on coated or uncoated PLGA film surfaces, and then we examined the cell attachment and proliferation by cell count and scanning electron microscopy observation. In addition, we evaluated relative messenger RNA expression of neuronal cell‐adhesion molecules by reverse transcription polymerase chain reaction. Cell count results revealed differences caused by initial cell adhesion related to protein adsorption on the PLGA surface. In addition, neurite outgrowth and the proliferation rate of OECs or SCs revealed differences according to the presence of serum in the medium. As a result, we recognized that the attachment and proliferation of OECs or SCs were affected by specific cell‐adhesive molecules. In conclusion, the selection of optimal adhesive molecules is an important consideration for manufacturing nerve guidance and neural cell cultures for tissue‐engineered nerve regeneration. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008

Encapsulation of Protein-Loaded Hydroxyapatite Granules with Poly (lactic-co-glycolic acid)

A solid-in-oil-in-water (S/O/W) emulsion-solvent evaporation method was applied to encapsulate protein-loaded hydroxyapatite (HAp) granules (D50=19.5 μm) with a biodegradable polymer of poly (lactic-co-glycolic acid) (PLGA). After loading bovine selum albumin (BSA), the HAp granules were mechanically dispersed in oil phase (PLGA dissolved in CH2Cl2), and then the suspension was dropped into water containing an emulsion stabilizer of polyvinyl alcohol (PVA). Stirring of the dropped suspension in the water phase produced S/O/W emulsions. The emulsions were diluted with excess water to facilitate removal of the organic solvent (CH2Cl2) from the oil phase. After the evaporation of CH2Cl2, the particulate materials were separated, washed and vacuum-dried. The resultant particles had very smooth PLGA surface with spherical shape, and their mean particle size was about several microns larger than that of the HAp granules. Fluorescently-labeled confocal laser scanning microscopy (CLSM) revealed that the protein-loaded HAp granules were encapsulated in the PLGA microsphere.

PLGA nanometer surface features manipulate fibronectin interactions for improved vascular cell adhesion

The largest cause of mortality in the Western world is atherosclerotic vascular disease. Many of these diseases require synthetic vascular grafts; however, their patency rate is only 30% in small (<6 mm) diameter vascular grafts after 5 years of implantation. In an effort to increase small diameter vascular graft success, researchers have been designing random nanostructured surface features which enhance vascular cell functions. However, for the present study, highly-controllable, nanostructured features on poly(lactic-co-glycolic acid) (PLGA) surfaces were formulated. To create ordered nanostructured roughness on PLGA surfaces, either 500, 200, or 100 nm polystyrene nanospheres were separately placed onto mica. These were then used as a template for creating an inverse poly(dimethylsiloxane) mold which was utilized to cast PLGA. Compared to all other PLGA films formulated, AFM results demonstrated greater initial fibronectin spreading on PLGA which possessed spherical 200 nm features. Compared to smooth PLGA, PLGA with 500 or 100 nm surface features, results further showed that PLGA with 200 nm spherical features promoted vascular cell (specifically, endothelial, and smooth muscle cell) adhesion. In this manner, the present study demonstrated a specific nanometer surface feature size that promoted fibronectin spreading and subsequent vascular cell adhesion; criteria critical to vascular graft success.

The effect of oxygen plasma pretreatment and incubation in modified simulated body fluids on the formation of bone-like apatite on poly(lactide-co-glycolide) (70/30)

In this study, biodegradable poly(lactide-co-glycolide) (PLGA) (70/30) films and scaffolds were first treated with oxygen plasma and then incubated in a modified simulated body fluid 1.5SBF0 to prepare a bone-like apatite layer. The formation of the apatite and its influence on osteoblast-like cells growth were investigated. It was found that the bone-like apatite formability of PLGA(70/30) was enhanced by plasma pretreatment. The changes of surface chemistry and surface topography induced by oxygen plasma treatment were both effective for apatite formation. The apatite formability increased with increasing plasma-treating time. Under a treating condition of 20 W for 30 min, oxygen plasma treatment could penetrate into the inner scaffold. After 6 days incubation, the apatite formed in plasma-treated scaffold was better distributed than in untreated scaffold, and the weight and mechanical strength of the plasma-treated scaffold were both enhanced. Compared with PLGA(70/30), the apatite layer formed on oxygen plasma-treated PLGA(70/30) surface enhanced adhesion and proliferation of OCT-1 osteoblast-like cell, but had no significant effect on cell's ALP activity at day 7. A prolonged investigation is being in process to further verify the bone-like apatite effects on osteogenic differentiation.

Immobilization of poly(ɛ-caprolactone)–poly(ethylene oxide)–poly(ɛ-caprolactone) triblock copolymer on poly(lactide- co-glycolide) surface and dual biofunctional effects

Poly(ɛ-caprolactone)–poly(ethylene oxide)–poly(ɛ-caprolactone) (PCL–PEG–PCL) triblock copolymer was covalently immobilized onto poly(lactide- co-glycolide) (PLGA) surface with the precursor of photopolymerizable and biodegradable PCL–PEG–PCL diacrylates. Argon plasma technique was exploited to obtain hydrophilic PLGA surface (HPLGA). The surface properties were characterized by Water contact angle and X-ray photoelectron spectroscopy (XPS) techniques. PCL–PEG–PCL surface modified hydrophobic PLGA and hydrophilic PLGA results in different surface physicochemical properties. PCL–PEG–PCL modified hydrophobic PLGA surface (PLGA–PCL–PEG–PCL) demonstrates excellent inhibition of platelet adhesion and activation; while PCL–PEG–PCL modified hydrophilic PLGA surface (HPLGA–PCL–PEG–PCL) results in good cytocompatibility. The possible mechanism was discussed and the driven force was ascribed to the different assembly behavior of PCL–PEG–PCL on PLGA surface dependant on the hydrophilic/hydrophobic property of PLGA. This simple and effective surface engineering method is also suitable for the other biomaterials such as polyurethane (PU), silicon rubber and poly(ethylene terephthalate) (PET) to obtain the enhanced biocompatibility.

A Blank Slate? Layer-by-Layer Deposition of Hyaluronic Acid and Chitosan onto Various Surfaces

Although poly(alpha-hydroxy esters), especially the PLGA family of lactic acid/glycolic acid copolymers, have many properties which make them promising materials for tissue engineering, the inherent chemistry of surfaces made from these particular polymers is problematic. In vivo, they promote a strong foreign-body response as a result of nonspecific adsorption and denaturation of serum proteins, which generally results in the formation of a nonfunctional fibrous capsule. Surface modification post-production of the scaffolds is an often-utilized approach to solving this problem, conceptually allowing the formation of a scaffold with mechanical properties defined by the bulk material and molecular-level interactions defined by the modified surface properties. A promising concept is the so-called "blank slate": essentially a surface that is rendered resistant to nonspecific protein adsorption but can be readily activated to covalently bind bio-functional molecules such as extracellular matrix proteins, growth factors or polysaccharides. This study focuses on the use of the quartz crystal microbalance (QCM) to follow the layer-by-layer (LbL) electrostatic deposition of high molecular weight hyaluronic acid and chitosan onto PLGA surfaces rendered positively charged by aminolysis, to form a robust, protein-resistant coating. We further show that this surface may be further functionalized via the covalent attachment of collagen IV, which may then be used as a template for the self-assembly of basement membrane components from dilute Matrigel. The response of NIH-3T3 fibroblasts to these surfaces was also followed and shown to closely parallel the results observed in the QCM.