Building a better PCR test

DOUGLAS FARMER, SENIOR EDITOR doug.farmer@photonics.com

The spread of infections caused by variants of the coronavirus issues a stark reminder to the medical and scientific communities, and to the rest of us who rely on these communities, that the COVID-19 pandemic is here to stay for the foreseeable future. Late in 2021, the World Health Organization (WHO) labeled variant B.1.1.529, commonly called omicron, as a variant of concern. Travel restrictions and other measures were imposed, along with ramped-up vaccination efforts, in an attempt to contain its spread.

The WHO has also urged enhanced surveillance and sequencing efforts to monitor the spread of the virus, including laboratory-based assessments that capture and assess telltale markers of COVID-19 and its various mutations. One of the common diagnostic mechanisms for identifying the disease is the polymerase chain reaction (PCR) test, which amplifies the presence of certain biomarkers for optical identification and detection of the illness. For rapid testing, quantitative PCR (qPCR) test components include a reaction module, an optical system, and software to extrapolate the data.

Jason Palidwar writes in our cover story in this issue of BioPhotonics that the optical system contains fluorescent elements, beam steering, and wavelength-selective elements — including optical filters — and sensors or detectors. The optical filter sets (excitation, dichroic beamsplitter, or emission) for each channel work together to block unwanted illumination and allow only certain wavelengths to pass through. Companies that produce qPCR technology must strike a balance between the components required to exact the information needed and commercial feasibility. Learn more here.

Elsewhere, Mihaela Balu relates that — to create a compact, yet powerful system to image skin disease — a research project was undertaken to enhance existing methods of multiphoton microscopy. The development brings a compact femtosecond fiber laser directly into a microscopic imaging head, along with other associated optical mechanisms for laser scanning and beam expansion, to provide the resolution needed to identify cellular dynamics in the skin. Read about the research on here.

In another research collaboration, Els Parton and Elena Beletkaia reveal the use of microscopy along with a miniaturized hyperspectral imaging camera — complete with a line-scan sensor — to track structural changes in the eyes of Alzheimer’s disease patients. The work opens the door to noninvasively detecting the disease in its early stages, before debilitating symptoms have ensued. See what’s in store here.

Also in this edition, Krzysztof Bec and Christian Huck explain that, thanks in part to the miniaturization of sensors, NIR spectroscopy — with its unique ability to provide for multivariate analysis while evaluating the molecular composition in a sample over a wide area — has allowed for many applications of the technology. These include agricultural and environmental monitoring. Find out what some of the latest research has enabled here.

Finally, in “Biopinion,” Ulysses Balis addresses standardization. He writes that — with the explosion of data collection — establishing universal standards for deep learning becomes essential in the fields of data science and clinical informatics. Balis argues that both coordinated and standardized data representation and an appropriate programming interface are needed. Otherwise, a treasure trove of information will exist whose meaning will not be widely understood or put to good use. Learn about his hopes for a standardized future in the data here.

Enjoy the issue!