Photochemical Grafting and Patterning of Biomolecular Layers onto TiO₂ Thin Films

Abstract

TiO2 thin films are highly stable and can be deposited onto a wide variety of substrate materials under moderate conditions. We demonstrate that organic alkenes will graft to the surface of TiO2 when illuminated with UV light at 254 nm and that the resulting layers provide a starting point for the preparation of DNA-modified TiO2 thin films exhibiting excellent stability and biomolecular selectivity. By using alkenes with a protected amino group at the distal end, the grafted layers can be deprotected to yield molecular layers with exposed primary amino groups that can then be used to covalently link DNA oligonucleotides to the TiO2 surface. We demonstrate that the resulting DNA-modified surfaces exhibit excellent selectivity toward complementary versus noncomplementary target sequences in solution and that the surfaces can withstand 25 cycles of hybridization and denaturation in 8.3 M urea with little or no degradation. Furthermore, the use of simple masking methods provides a way to directly control the spatial location of the grafted layers, thereby providing a way to photopattern the spatial distribution of biologically active molecules to the TiO2 surfaces. Using Ti films ranging from 10 to 100 nm in thickness allows the preparation of TiO2 films that range from highly reflective to almost completely transparent; in both cases, the photochemical grafting of alkenes can be used as a starting point for stable surfaces with good biomolecular recognition properties.

Nanofabrication of Metal Oxide Patterns Using Self-Assembled Monolayers

“…Especially, 2D patterns of tin oxide nano-structures on flexible polymer films are required for light-weight flexible sensors and solar cells. 2D patterning of nanomaterials 119,120 such as metal oxides 33,54,63,75,121,122 , Au clusters 123 , Pt nanoparticles 124 , organic monolayers 125 , bio molecular layers 126 , DNA 127 , etc. is expected to lead to a large step forward in materials science research and the development of new devices.…”

Molecular and biomolecular interfaces to metal oxide semiconductors

“…The detailed procedures involved in linking DNA to the functionalized surfaces have been reported previously [1,25,26] and are illustrated in Fig. 1.…”

“…A bifunctional cross-linked such as sulfosuccinimidyl 4-(N-maleimidomethyl) cyclohexane-1-carboxylate (SSMCC) is then used link thio-modified DNA to the amino-terminated surface. To explore hybridization at DNA-modified TiO 2 surfaces, we linked thioterminated DNA oligonucleotides with two different sequences, differing by 4 bases, to the surface [26]. These sequences are 5'-HS-C6H12-GC TTA TCG AGC TTT CG-3' (S1) and 5'-HS-C6H12-GC TTA AGG AGC AAT CG-3' (S2).…”

Site‐Selective Chemical Reaction on Flexible Polymer Films for Tin Oxide Nanosheet Patterning

“…In particular, 2D patterns of tin oxide nanostructures on flexible polymer films are required for light-weight, flexible sensors and solar cells. 2D patterning of nanomaterials [18,19] such as metal oxides, [20][21][22][23][24][25] Au clusters, [26] Pt nanoparticles, [27] organic monolayers, [28] bimolecular layers, [29] and DNA [30] is expected to lead to a large step forward in materials science research and the development of new devices.…”