Application of Kinetic Doping of Silica Sol-Gel Thin Films to Internal Coating of Capillary Tubes and Doping of Branched Polyethylenimine

Doped or functionalized silica thin films are highly desirable technologies for many chemical applications. Current procedures for doping can be costly, environmentally unfriendly, require many synthetic steps, or have low doping efficiency. Kinetic doping is a technique for loading guest molecules into sol-gel thin films that involves introducing guest molecules into a still-evolving film, allowing them to be entrapped by the growing silica network developed by the Yip lab. It has been shown to have high doping efficiency, high ease of use, and low cost when doping cationic dyes and enzymes on flat-surface films. Expanding on this work, we developed parameters for internally doping capillary tubes that allowed for highly efficient loading of the enzyme horseradish peroxidase. Additionally, we utilized kinetic doping to functionalize silica thin films with 1800, 25000, and 750000 molecular weight branched polyethylenimine (BPEI), a highly basic molecule that – to our knowledge – had never been doped into silica thin films before. Two applications of these films were tested: the copper (II) sequestration capacity of the 25000 molecular weight films and the efficacy of all three molecular weight films against S. epidermis biofilms. The films proved to have great potential for both heavy metal sequestration and as an anti-biofilm coating.