Theam Soon Lim

By Qiuting Loh and Theam Soon Lim

The versatile DNA G-quadruplex structure has emerged as an interesting alternative reporter system applied in different biosensor platforms. In comparison to the conventional reporter systems like enzymatic or fluorescent, DNA G-quadruplex has some distinct advantages, as it is thermostable, easy to produce, low cost and most importantly able to be amplified. Such remarkable advantages have led many researchers to exploit DNA G-quadruplex as the reporter system in colorimetric, fluorescence and luminescence sensors. There has also been integration of DNA G-quadruplex with electrochemical methods and quantum dot for sensing applications. Therefore, this chapter highlights some recent examples of different biosensor platforms that use DNA G-quadruplex as a reporter system with different detection methods.

Part of the book: Nucleic Acids

By S. W. Leong, T. S. Lim and Y. S. Choong

Biological membranes are complex environments consisting of different types of lipids and membrane proteins. The structure of a lipid bilayer is typically difficult to study because the membrane liquid crystalline state is made up of multiple disordered lipid molecules. This complicates the description of the lipid membrane properties by the conformation of any single lipid molecule. Molecular dynamics (MD) simulations have been used extensively to investigate properties of membrane lipids, lipid vesicles, and membrane protein systems. All-atom membrane models can elucidate detailed contacts between membrane proteins and its surrounding lipids, while united-atom and coarse-grained description have allowed larger models and longer timescales up to microsecond mark to be probed. Additionally, membrane models with mixed phospholipids and lipopolysaccharide content have made it possible to model improved views of biological membranes. Here, we present an overview of commonly used lipid force fields by the biosimulation community, useful tools for membrane MD simulations, and recent advances in membrane simulations.

Part of the book: Bioinformatics

By Angela Chiew Wen Ch’ng, Yee Siew Choong and Theam Soon Lim

Antibodies are produced by the human body in response towards infections as a means of protection. The in vivo production of antibodies by B-cells involves a series of intricate gene editing processes resulting in a highly diverse pool of antibodies. However, this diversity can be replicated in vitro using phage display. Phage display offers the potential to present the antibody phenotype together with the cloned genotype of the specific antibody in a single-phage particle. Antibodies are highly sought after for diagnostic applications owing to its specificity and affinity towards a target antigen. The advent of recombinant antibody (rAb) technology allows for a faster and more cost-effective solution for antibody generation. It also provides diagnostic developers with the possibility to customize the antibodies. Antibodies have been utilized successfully in various diagnostic platforms ranging from standard immunoassays to lateral-flow assays, nanoparticles, microfluidics, DNA‐integrated assays and others. The limitless application of antibodies in the field of diagnostics has made it a critical component in any diagnostic development platform. This chapter focuses on the processes involved in antibody discovery including the various forms of antibody libraries for phage display and panning processes. We also highlight some diagnostic platforms that apply recombinant antibodies.

Part of the book: Proof and Concepts in Rapid Diagnostic Tests and Technologies

By Chia Chiu Lim, Yee Siew Choong and Theam Soon Lim

Recombinant human antibody technology has been the cornerstone of the uprising of biologics in the pharmaceutical industry. The introduction of various display technologies like phage, yeast, bacterial, ribosomal, mRNA, DNA display and mammalian cell surface display has allowed improved antibody generation programs. The ability to generate recombinant antibodies from available human antibody libraries by using in vitro display methods pave the way to select recombinant human antibodies against almost every antigen. The libraries are a close representation of the B-cell response elicited by the natural immune system. The introduction of various methods to fine tune the antibody affinities has made recombinant antibody technology highly sought after. The ability to engineer specific characteristics of each antibody by design is possible utilizing advanced in vitro strategies. This chapter will focus on the technologies commonly applied in antibody display technologies to engineer improved affinities.

Part of the book: Antibody Engineering