Patterned and switchable surfaces for biomaterial applications

Andrew Hook – Patterned and switchable surfaces for biomaterial applicationsprotein that will enhance transfection efficiency depends on the cell line used. Forexample, the use of collagen IV as a surface coating improved transfection efficiencyup to 8-fold in PC12, where fibronectin showed little effect [172]. This contrasts withprevious studies done with HEK cells, human mesenchymal stem cells, HenriettaLack (HeLa) cells, normal mouse fibroblasts and human hepatocellular livercarcinoma where high solid state transfection efficiencies were achieved with theaddition of fibronectin [173]. The postulated mechanism for ECM proteinspromoting transfection efficiency is the mechanical stress that these proteins inflictupon the cellular membrane, easing the uptake of DNA through the stressed cellmembrane.A number of proteins such as transferrin, adenoviral penton protein and humanimmunodeficiency virus Tat protein have also been shown to improve transfectionefficiency and have been applied to TCM applications successfully [155]. Of allproteins used, inclusion of the adenoviral penton protein has achieved the highesttransfection efficiencies. The mechanism for this is unknown.1.4.4.4. DNA expressionThe final step in the formation of a TCM is the expression of the uptaken DNA bythe cell. This process is complex and beyond the scope of this chapter.Green fluorescing protein (GFP) is often used as a reporter protein to ensure that aparticular plasmid has been taken up and is being expressed intracellularly.Interestingly, a variance in the intensity of fluorescence of cells transfected by a GFPencoding gene has been noted and the fluorescence intensity seems to correlate withthe number of plasmids or DNA fragments taken up by a cell.One of the challenges for TCMs is the analysis of potentially thousands ofindividual cell colonies each displaying a different phenotype, often requiring1-57