Tiny tweezers help fat fingers do nimble tasks
Ever wish you had teeny tiny tweezers to pull a teeny tiny splinter from your pinky?
You’re in luck.
Researchers have developed easy-to-use “microtweezers” that are up to the task, and much more, such as plucking a cluster of stem cells from a petri dish and building all sorts of little mechanical devices.
Despite its simple design, the sensor is highly-sensitive and precise.
Cagri Savran, study leader and an associate professor of mechanical engineering at Purdue University, along with Babak Ziaie, a Purdue University professor of electrical and computer engineering and biomedical engineering, and a team of researchers, are developing a low-cost, highly-sensitive biological and chemical sensor that can detect changes in the pH level of an environment without needing several moving parts.
As medicine moves closer to personalization and targeted therapy, the need for diagnostics that can rapidly and accurately predict and monitor the occurrence and progression of disease and drug treatments becomes critical. In an article published in the Journal of the American Chemical Society (Vol. 129, No. 51, Nov. 2007), Prof. Çağrı A. Savran demonstrated the use of a relatively cheap and easy-to-use biosensor for detecting serum-based protein biomarkers indicative of various types of cancers.
In the quest for an improved biomarker detection method, Cagri Savran and colleagues at Purdue University and the Mayo Clinic have designed a new technique called immunomagnetic diffractometry. Their approach combines the immunomagnetic capture of an analyte on beads, in situ assembly of an optical diffraction grating, and measurement of the diffraction. In this method, magnetic beads capture the target from the serum sample and bind to a surface to form the diffraction gratings. By virtue of their size, the beads enhance the diffraction signal, so no further signal amplification or labeling is needed. The target chosen for the proof-of-principle study was the folate receptor (FR), a potential serum biomarker for cancer. With microcontact printing, the researchers deposited alternating 15 μm lines of folate-coupled bovine serum albumin (F–BSA) onto a gold surface. Magnetic beads derivatized with the FR antibody (FR–beads) captured FR from serum and subsequently bound to the F–BSA lines. The bound molecules and beads effectively formed a grating that diffracted the incident laser radiation. The researchers observed that the FR–beads attached specifically to the F–BSA on the surface. The packing density of the bound FR–beads intensified with increasing FR concentrations (700 fM to 11 nM). After creating a calibration curve, the researchers measured the FR concentration in the serum of cancer patients. The detection limit of immunomagnetic diffractometry was lower than that of several other biomarker assays such as ELISAs. Immunomagnetic diffractometry has the additional advantages of speed, robustness, low cost, and ease of miniaturization. The researchers say that the assay is applicable to other biomarkers. (J. Am. Chem. Soc. 2007, 129, 15,824–15,829)
Hydrogel used to create precise new biochemical sensor.
Scientists have used gelatinous hydrogel to create an inexpensive new type of biochemical sensor that is highly sensitive, sturdy, long-lasting, and has few moving parts. The gel expands or contracts according to the acidity of its environment, a quality that allows the sensor to measure changes in pH down to one one-thousandth on the pH scale. This amount of accuracy, along with its robustness, could make it ideal for chemical and biological applications such as environmental monitoring in waterways and glucose monitoring in blood.