Photocatalytic Lithography with Atomic Layer–Deposited TiO₂ Films to Tailor Biointerface Properties

Abstract

In this article, the use of thin, photocatalytically active TiO2 films deposited using atomic layer deposition (ALD) and a conventional lithography mask are explored for the fabrication of a patterned biointerface. Hereto, a pattern of self‐assembled monolayers (SAMs) with different functional groups is created using ALD TiO2 films, anatase‐rich as‐deposited, with a thickness of 20 nm and a short UV exposure time of 5 min. More specifically, azido‐containing SAMs are locally removed upon UV exposure (λ = 308 nm) and the created gaps are filled with a polyethylene glycol (PEG) SAM, hereby creating a surface with areas for the selective coupling of biomolecules via the azide groups and antifouling areas due to the presence of the PEG. To demonstrate the effectiveness of this approach, fluorescent‐labeled antibodies are immobilized on the well‐defined patterns with a resolution in the µm range.

Functional Materials with Wide‐Spectral‐Responsive Photocatalytic Activity and Real‐Time Temperature Feedback: The Electrospun Fibers Embedded with NaGdF4‐Tm‐Yb@TiO2 Nanocrystals

“…To further assess the photocatalytic activity, the fitting curves of kinetic rate are illustrated in Figure 13b, where the kinetics rate follows a first-order model ln(C 0 /C) = kt. [63][64][65] It is clearly that the NGF-T 0.4 Y 6 @TiO 2 /PAN composite fibers have the highest rate among all the samples, which confirms that they have good ability to degrade pollutants under Xe lamp irradiation.…”

An IR Spectroscopy Study of the Degradation of Surface Bound Azido-Groups in High Vacuum

“…This is also indicated by contact angle measurements performed on the sample after vacuum treatment and on a N 3 –SAM reference sample, which are respectively (86.43 ± 0.40)° and (83.1 ± 1.3)°. Upon removal of complete silane molecules from the N 3 –SAM by for example photocatalytic degradation on a TiO 2 surface, the contact angle is observed to decrease with tens of degrees due to the removal of the hydrophobic carbon chain and exposure of hydrophilic hydroxyl groups at the surface …”

“…In addition, the density of functional groups at the surface for immobilization of biomolecules might influence the orientation of the molecules and have a significant effect on the signal obtained during biological assays . Various applications require patterned micro- and nanostructures using azide based chemistry . Therefore, one should be aware of the azide degradation altering the foreseen surface functionalization, not only during deposition of an azido-containing film in high vacuum but also when performing processing steps in vacuum after the introduction of azido-groups to the surface.…”

“…Upon removal of complete silane molecules from the N 3 −SAM by for example photocatalytic degradation on a TiO 2 surface, the contact angle is observed to decrease with tens of degrees due to the removal of the hydrophobic carbon chain and exposure of hydrophilic hydroxyl groups at the surface. 68 To our knowledge few literature reports mention the degradation of azides in high vacuum. Bebensee et al 33 observed a low yield of the azide−alkyne click-reaction in ultra high vacuum on Cu(111).…”

A High Catalytic Activity Photocatalysts Based on Porous Metal Sulfides/TiO2 Heterostructures

“…[ 14–16 ] Moreover, the low quantum efficiency of TiO 2 results in a fast recombination rate of the photogenerated electrons and holes, which significantly deteriorates its catalytic performance. [ 17–20 ] To conquer these drawbacks, numerous approaches have been proposed, such as depositing noble metal (Pt, Au, and Ag), [ 21–23 ] doping with metal or nonmetal elements (Sn 4+ , Mn 4+ , Co 2+ , Ni 2+ , N, and S), [ 24–30 ] and coupling with small bandgap materials (metal oxides or metal sulfides). [ 31–36 ] Among these strategies, hybridization with narrow bandgap metal sulfides (such as CdS, MoS 2 , and CuS) is considered the most effective method, as the wide visible light absorption and small band structure of metal sulfides can greatly enhance the catalytic activity of TiO 2 .…”