Based upon the binding specificity of antibodies to target molecules, immunohistochemistry (IHC) has been used in labs for decades to research protein expression, or lack thereof, in tissue samples. It’s a great example of a translational technique that is being used every day in hospital pathology labs around the world to, for example, classify tumor biopsies based on diagnostic markers. This in turn informs the prognosis and treatment options for the patient from whom the biopsy was taken. However IHC remains a tedious process that involves multiple conjugation steps to bind antibodies to and color-code the target molecules; mistakes can lead to over- and under-exposure which renders the sample unusable and inconclusive.
The technique may have just gotten more sensitive thanks to IBM researchers. Reporting in today’s online issue of Lab on a Chip, the team has developed an ultra-miniaturized probe for immunohistochemistry. According to the press release:
The eight millimeter-wide, diamond-shaped probe consists of a silicon microfluidic head with two microchannels at each tip. Similar to an inkjet printer cartridge, the head injects the liquid on the surface, but then unlike a printer, it continuously aspirates the liquid to prevent spreading and accumulation on the surface, which can lead to overexposure.
Specifically for tissue section analysis, the probe can deliver an antibody very locally in a selected area of a tissue section with pinpoint accuracy. Since analysis can be done on spots and lines instead of on the entire
tissue section, the tissue is better preserved for additional tests, if required. In addition, only a few picoliters (one trillionth of a liter) of liquid containing antibodies are needed for each analysis spot.
Though at this stage the probe is proof-of-concept, it may not be long before pathology labs can make more accurate diagnoses with even smaller biopsy samples.
Paper in Lab on a Chip: Micro-immunohistochemistry using a microfluidic probe