Layer-by-layer assembly of chondroitin sulfate and collagen on aminolyzed poly(l-lactic acid) porous scaffolds to enhance their chondrogenesis

Layer-by-layer (LBL) assembly of cytocompatible chondroitin sulfate (CS) and collagen type I (Col) onto PLLA scaffolds were implemented to enhance the cell–material interaction. To introduce charges onto the hydrophobic and neutral PLLA surface so that the electronic assembly can be processed, the PLLA was aminolyzed in hexane diamine solution to obtain free amino groups that are positively charged at neutral pH. Ultaviolet–visible spectroscopy and ninhydrin analysis verified the consecutive deposition of CS/Col multilayers on the aminolyzed PLLA membranes. Confocal laser scanning microscopy (CLSM) observation and hydroxyproline quantification revealed the process of LBL assembly of CS/Col multilayers in the interior of PLLA porous scaffolds. In vitro chondrocyte culture found that the presence of CS and Col greatly improved the cytocompatibility of the PLLA scaffolds in terms of cell attachment, proliferation, cytoviability and GAG secretion.