Editing Biosensor (section)

=== Metastatic cancer cell detection ===

Metastasis is the spread of cancer from one part of the body to another via either the circulatory system or lymphatic system.<ref>{{cite journal | last1 = Hanahan | first1 = Douglas | last2 = Weinberg | first2 = Robert A. | year = 2011 | title = Hallmarks of Cancer: The Next Generation | journal = Cell | volume = 144 | issue = 5| pages = 646–74 | doi=10.1016/j.cell.2011.02.013 | pmid=21376230| doi-access = free }}</ref> Unlike radiology imaging tests (mammograms), which send forms of energy (x-rays, magnetic fields, etc.) through the body to only take interior pictures, biosensors have the potential to directly test the malignant power of the tumor. The combination of a biological and detector element allows for a small sample requirement, a compact design, rapid signals, rapid detection, high selectivity and high sensitivity for the analyte being studied. Compared to the usual radiology imaging tests biosensors have the advantage of not only finding out how far cancer has spread and checking if treatment is effective but also are cheaper, more efficient (in time, cost and productivity) ways to assess metastaticity in early stages of cancer.

Biological engineering researchers have created oncological biosensors for breast cancer.<ref name="Atay, Seda 2016">{{cite journal | last1 = Atay | first1 = Seda | last2 = Pişkin | first2 = Kevser | last3 = Yılmaz | first3 = Fatma | last4 = Çakır | first4 = Canan | last5 = Yavuz | first5 = Handan | last6 = Denizli | first6 = Adil | year = 2016 | title = Quartz Crystal Microbalance Based Biosensors for Detecting Highly Metastatic Breast Cancer Cells via Their Transferrin Receptors | journal = Anal. Methods | volume = 8 | issue = 1| pages = 153–61 | doi = 10.1039/c5ay02898a }}</ref> Breast cancer is the leading common cancer among women worldwide.<ref>Nordqvist, Christian. "Breast Cancer Cancer / Oncology Women's Health / Gynecology Breast Cancer: Causes, Symptoms and Treatments." Medical News Today. N.p., 5 May 2016. Web.</ref> An example would be a transferrin- quartz crystal microbalance (QCM). As a biosensor, [[quartz crystal microbalance]]s produce oscillations in the frequency of the crystal's standing wave from an alternating potential to detect nano-gram mass changes. These biosensors are specifically designed to interact and have high selectivity for receptors on cell (cancerous and normal) surfaces. Ideally, this provides a quantitative detection of cells with this receptor per surface area instead of a qualitative picture detection given by mammograms.

Seda Atay, a biotechnology researcher at Hacettepe University, experimentally observed this specificity and selectivity between a QCM and [[MDA-MB 231]] breast cells, [[MCF 7]] cells, and starved MDA-MB 231 cells in vitro.<ref name="Atay, Seda 2016"/> With other researchers she devised a method of washing these different metastatic leveled cells over the sensors to measure mass shifts due to different quantities of transferrin receptors. Particularly, the metastatic power of breast cancer cells can be determined by Quartz crystal microbalances with nanoparticles and transferrin that would potentially attach to transferrin receptors on cancer cell surfaces. There is very high selectivity for transferrin receptors because they are over-expressed in cancer cells. If cells have high expression of transferrin receptors, which shows their high metastatic power, they have higher affinity and bind more to the QCM that measures the increase in mass. Depending on the magnitude of the nano-gram mass change, the metastatic power can be determined.

Additionally, in the last years, significant attentions have been focused to detect the biomarkers of lung cancer without biopsy. In this regard, biosensors are very attractive and applicable tools for providing rapid, sensitive, specific, stable, cost-effective and non-invasive detections for early lung cancer diagnosis. Thus, cancer biosensors consisting of specific biorecognition molecules such as antibodies, complementary nucleic acid probes or other immobilized biomolecules on a transducer surface. The biorecognition molecules interact specifically with the biomarkers (targets) and the generated biological responses are converted by the transducer into a measurable analytical signal. Depending on the type of biological response, various transducers are utilized in the fabrication of cancer biosensors such as electrochemical, optical and mass-based transducers.<ref>{{cite journal |title=Electrochemical biosensors for the detection of lung cancer biomarkers: A review |journal=Talanta |volume=206 |pages=120251 |doi=10.1016/j.talanta.2019.120251 |pmid=31514848 |year=2020 |last1=Khanmohammadi |first1=Akbar |last2=Aghaie |first2=Ali |last3=Vahedi |first3=Ensieh |last4=Qazvini |first4=Ali |last5=Ghanei |first5=Mostafa |last6=Afkhami |first6=Abbas |last7=Hajian |first7=Ali |last8=Bagheri |first8=Hasan |doi-access=free }}</ref>