Passive and active approaches to tackle antifouling

• Main Author: Gaw, Sheng Long
• Other Authors: Lee Pooi See
• Format: Theses and Dissertations
• Language: English
• Published: 2019
• Subjects: Engineering::Materials
• Online Access: https://hdl.handle.net/10356/106677; http://hdl.handle.net/10220/48934
• Institution: Nanyang Technological University

Biofouling is the accumulation of unwanted organisms on a surface. Biomedical and marine industries are of are two main particular interest for this study. Biofouling in marine industry reduces the performance of the equipment, leading to an increase in operating cost and downtime. In the medical industry, it can lead to catastrophic effects on the patient and might lead to death in the event of bacterial infection. Till date, there is no absolute solution to this problem. Therefore, this study provides a valuable contribution to the community by providing three novel antifouling methods. Biofouling is initiated with the formation of biofilms and other micro-organisms before large organisms started to adhere. Biofilms are usually formed with the colonization of bacteria. The current state of the art has provided solutions to either preventing (antifouling) or destroys (antimicrobial) micro-organism adhering on the surface. This thesis has also reviewed the current state of the art and categories the prior works to either active or passive approaches for the solution to prevent biofouling. An active approach via electrochemical reaction for generating antifouling surfaces through the formation of a hydrogen gas bubble layer was achieved. It attained through the application of a low voltage square-waveform pulse to the conductive surface. This electrochemically generated gas bubble layer serves as a separation barrier between the surrounding and the target surface where the adhesion of bacteria can be deterred. It has proven to prevent 99.5% of Escherichia coli from adhering onto the surface. In order to put this system into a practical application, the need to reduce the energy consumption is required. A multilayer polyvinyl butyral scaffold film on the stainless steel substrate has reduced the amount of energy required by 96x to a single pulse in 16 hours. This polyvinyl butyral film will reduce the E.coli binding strength on the surface. During the electrochemical reduction process, the Escherichia coli will be released from the surface. This method has been proven effective for accelerated bacteria study and the polyvinyl butyral is stable in Lysogeny broth after prolonged cycling. This study also serves as a new viable antifouling solution which is applicable to all conductive substrate. Due functionality of the system, the active approach via electrochemical reaction might not be suitable. For instance, this method does not cater to biomedical devices as it requires tissue growth around the implants to achieve stability and functionality. Passive approach such as coating is a feasible choice. One of the environmentally friendly highly sought after biocompatible antifouling materials is peptide. It is made up of amino acids and it can be easily synthesized by the combination of different amino acids in random or alternate arrangements to attain the desired functionality. This work has provided insights on the different antifouling properties of the peptides when manipulating the positions of the amino acids within the peptide chains. It offers an important milestone for future peptide antifouling research. The antifouling performance of the peptides chain was not solely dependent on the properties of each amino acids but the sequencing of the amino acids within the peptide chain.