Background
Diagnosis of disease is of paramount importance for rapid administration of appropriate therapy. Traditional methods such as culture, morphological examination of tissue samples and ELISA are time consuming and labour intensive. Our technology provides a rapid, label-free method of detection and identification and has the potential for applications both in centralised testing laboratories and for on site testing using simple, low cost products. In addition, the technique works without the need for labelling or extensive sample preparation; for example it can be applied to whole blood samples. The core component used for detection, an acoustic wave device, is employed in various forms in watches, mobile phones, computers and many other electronic devices.
Technology
By monitoring the change in resonant frequency of an acoustic wave device with appropriate surface chemistry and fluid delivery systems we are able to detect the adsorption of proteins, oligonucleotides such as DNA and RNA, cells, and other analytes to surface-bound receptors. This allows the label-free determination of analyte concentration in real time. In addition, it is possible to monitor other parameters of the resonator that give more detailed information about a molecular interaction. For example, the motional resistance of a device can give information on the conformation and visco-elastic properties of an analyte.
Benefits
CMI’s technology offers several major benefits over current diagnostic methods:
• Significant Reductions in Time to Result and Assay Cost: it is possible to use CMI’s acoustic detection technology with little or no sample preparation. Published experiments have demonstrated highly sensitive direct detection of ligands in complex fluids such as blood, serum, saliva and urine. Reduction or elimination of sample preparation also circumvents problems of contamination associated with amplification-based methods (e.g. culture and PCR) and will reduce risks of cross contamination, sample degradation and analyte loss. It also allows the use of simpler instrumentation that can be operated easily using less reagents.
• Simplified Assay Systems: unlike current biosensor-based assays, discrimination between specific and non-specific interactions is achieved by performing separation and detection in the same experiment without the requirement for washing steps. This also allows for a homogeneous assay format and enables the measurement to be performed in complex fluids, and for desired ligands to be collected for further analysis or identification if required.
• Increased Analysis Speed: CMI has developed methodology with a current assay time of less than 15 minutes. This compares to several days for culture based assays and 6 to 24 hours for molecular (PCR)-based assays.
• Label-free Detection: The lack of label in the system is highly advantageous as it is relatively simple to obtain a read-out, and there are no additional cost and time demands that result from the labelling process. The vast majority of diagnostic technologies require radio-, fluorescent- or chemiluminescent labelling of the analyte or receptor. This labelling step demands significant processing and quality control with substantial time and cost outlay. Labelling can also interfere with a molecular interaction by occluding a binding site, leading to false negatives (low sensitivity), or significant background binding leading to false positives (low specificity).
• Higher Information Content: Acoustic detection allows several parameters to be measured using one platform and one consumable: qualitative detection, quantitative detection, and conformational changes involved in an analyte-receptor interaction.
• Wide Range of Applications: There is no need for optics or scanning instrumentation and image recognition software. Detection is electronic, thus products will be hand-held for use at bedside, with health care professionals, at home or the office.
