Bradley Research Group
The Bradley Group has worked in the micro-array area for some four years and has led to the development of a generic HT screening method for the determination of the substrate specificity of proteases, kinases and phosphatases etc. (Interfacing DNA Arrays with Combinatorial Libraries, Chem. Commun., 2005 and the last paper 2006 presents a 10,000 member peptide library). With time interest in micro-arrays has been extended to include arrays based around small molecule and polymer based transfection agents (Polyplexes and Lipoplexes for Mammalian Gene Delivery (see: Traditional to Micro-array Screening, Combinatorial Chemistry and High-Throughput Screening, 2004, 447, in which libraries of small molecules within polymers were screened for their cellular transfection abilities (delivery of DNA into cells). This is important in so called gene therapy or antisense studies. Thus there is a need to be able to efficiently deliver DNA (or RNAi) into cells. This project aims to produce new reagents, tools and methods for DNA delivery.
Stem cell control and manipulation
The Bradley group has developed so called polymer micro-arrays. This is in essence a glass microscope slide with 2,000 different polymers printed in a spot like manner across the array. This array can then be screened with mammalian cells to identify polymers that are cell selective. We are currently interested in preparing arrays that will allow cell release, of finding polymers that will allow small molecules to be placed in the array to modulate cell phenotype (physical changes). Currently, a new approach to transfect mammalian cells on polymer microarray platforms has been achieved.
The successful and efficient introduction and delivery of materials into cells is of fundamental importance throughout many areas of biology. It is critical for the analysis of function, the perturbation of specific cellular processes, and the development of novel therapeutic strategies. The Bradley group has carried out numerous studies with small, mono-disperse, cross-linked beads (we can routinely prepare a variety of cross-linked beads from 200 nm - 5 µm) on a variety of cultured cell lines. Remarkably, and quite generally, these beads are taken up by cells These particles have a number of advantages over other approaches. Firstly, a diverse range of compounds can be attached to the microspheres including small molecule inhibitors, peptides, RNA and DNA. They are large enough to visualise using standard microscopy techniques (unlike nano-particles). They are not diluted within the cell. Populations of cells containing beads can be readily sorted automatically from other cells for subsequent analysis and it is possible to get very high uptake rates (this can be modulated through alteration of the bead size and incubation time).
HT Physical Organic Chemistry
The research group routinely uses high-thorough chemical methods to prepare chemical entities (why make one when in the same time you can make 10!). However to date little has been carried out in the area of utilising HT methods in physical organic chemistry for reaction predication, mechanistic interrogation and reaction profiling. We have begun to look at tools and chemistries to allow Hammett plots and reaction predictions to be determined by mass spectrometry with a single injection on an LCMS allowing complete interrogation and interpretation of a reaction. This research offers an approach that will enable the first steps to be taken forward for HT reaction prediction and the generation of kinetic parameters and challenges current philosophy in offering new methods orders of magnitude faster than those currently used.
Combinatorial chemistry evolved from work in the area of peptide chemistry, specially from the need to produce large munbers of products either by preparing single compounds in parallel synthesis or by preparing many compounds simultaneously in mixtures. Using combinatorial techniques these large numbers of compounds can be prepared in a faster, more efficient and cheaper way and can give rise to millions of compounds. These compounds can then be screened for the desired property (e.g. a new catalytic activity, enzyme inhibitor). Combinatorial Chemistry is now widely applied within the pharmaceutical industry as a means of identifying new leads (through random screens) and optimising the potency of feasible drug candidates (lead optimisation).