TISSUE ENGINEERING Volume 8, Number 5, 2002 © Mary Ann Liebert, Inc. Nanostructured Polymer/Nanophase Ceramic Composites Enhance Osteoblast and Chondrocyte Adhesion SARINA KAY, B.S., ANIL THAPA, M.S., KAREN M. HABERSTROH, Ph.D., and THOMAS J. WEBSTER, Ph.D. ABSTRACT Osteoblast (bone-forming cell) and chondrocyte (cartilage-synthesizing cell) adhesion on novel nano- structured polylactic/glycolic acid (PLGA) and titania composites were investigated in the present in vitro study. Nanostructured polymers were created by chemically treating micron-structured PLGA with select concentrations of NaOH for various periods of time. Dimensions of ceramics were controlled by utilizing either micron or nanometer grain size titania. Compared with surfaces with conventional or micron surface roughness dimensions, results provided the first evidence of increased osteoblast and chondrocyte adhesion on 100 wt% PLGA films with nanometer polymer surface roughness dimensions. Results also confirmed other literature reports of enhanced osteoblast ad- hesion on 100 wt% nanometer compared with conventional grain size titania compacts; however, the present study provided the first evidence that decreasing titania grain size into the nanometer range did not influence chondrocyte adhesion. Finally, osteoblast and chondrocyte adhesion in- creased on 70/30 wt% PLGA/titania composites formulated to possess nanosurface rather than con- ventional surface feature dimensions. The present study, thus, provided evidence that these nano- structured PLGA/titania composites may possess the ability to simulate surface and/or chemical properties of bone and cartilage, respectively, to allow for exciting alternatives in the design of pros- theses with greater efficacy. 753 INTRODUCTION C ONVENTIONAL CERAMICS such as titania and alumina with grain sizes in the micron range have long been appreciated for their biocompatibility with bone cells. However, these biomaterials have often clinically failed because of a lack of direct bonding with juxtaposed bone, that is, insufficient osseointegration. 1–5 Similarly, for car- tilage replacements, conventionalpolymers such as poly- tetrafluoroethylene with individual fiber dimensions in the micron range often fail to promote new cartilage for- mation necessary for clinical success. 5,6 Novel ceramic (hydroxyapatite derivatives, bioglasses, bioactive glass- ceramics, etc.) 7–10 and polymer (specifically, biodegrad- able polymers such as polylactic acid, polyglycolic acid, etc.) 11–17 three-dimensional scaffolds have been shown to enhance formation of bone and cartilage, respectively. The mechanical properties of these biosubstitutes, how- ever, are generally not comparable to surrounding tissue; consequently, use of these materials as bone/cartilage prostheses has been limited. 1,13,15 This is because bulk mechanical properties that do not duplicate those of sur- rounding tissue can result in stress and strain imbalances leading to poor tissue ingrowth, tissue resorption, and eventual implant loosening/failure. 2 One approach in the design of the next generation of orthopedic implant materials is to simulate the funda- mental length scales of constituent components of adja- Department of Biomedical Engineering, Purdue University, West Lafayette, Indiana.