Three times ten
The paper analytical device will find the picomoles of the analyte
ChemPort.Ru based on Chemical & Engineering News:
Paper Analytical Device Incorporates Electronic Components To Increase SensitivityAlthough paper-based analytical devices are a cheap way to determine chemicals, their accuracy is often not enough to detect compounds in low concentrations.
To overcome this problem, researchers were able for the first time to incorporate cheap electronic components into a paper device, which made it possible to increase the sensitivity of such a system and determine picomolar concentrations of biomolecules.
In regions with an undeveloped healthcare infrastructure, paper-based analytical devices can become a significant help in the work of doctors, allowing them to detect rare molecules in the blood of patients that are biomarkers of certain diseases.
However, as noted by Tsinghua Yu, unfortunately, in some cases, existing detection methods have a number of disadvantages that limit their practical application. The fact is that paper indicators that change color in the presence of certain substances in the analyzed mixture are characterized by low sensitivity, and devices whose analytical response consists in generating an electrical signal need expensive external equipment whose task is to amplify this weak signal.
Yu and his colleagues decided to lower the cost of a paper device by creating an analytical device that can generate electrical responses to a certain detectable substance without using additional equipment. Article by Lei Ge et al. Photoelectrochemical Lab-on-Paper Device Based on an Integrated Paper Supercapacitor and Internal Light Source is published in the journal Analytical Chemistry.
In a device created by Chinese researchers, the target molecule triggers a cascade of reactions that generate light. The device converts this light into an electric current, the strength of which is proportional to the concentration of the target molecule. The devices supplemented the device with an electronic component – a supercapacitor capable of amplifying electric current. This supercapacitor allows you to increase the current strength so much that it can be measured using a conventional portable multimeter. The supercapacitor was obtained by impregnating two sections of paper with an electrolytic gel, followed by bending the paper so that both impregnated sections were opposite each other.
To analyze the sample, the researchers first mixed the sample with gold nanoparticles coated with luminol, a compound that emits light in the presence of hydrogen peroxide, and short single–stranded DNA fragments binding to the target molecule were also deposited on the nanoparticles. The researchers then applied about 10 µl of the mixture to a piece of paper, after which they folded the paper, combining this section with a piece of paper coated with cadmium sulfide nanoparticles, to which DNA fragments capable of contacting the target molecule were also grafted. (The size of the biosensor can be compared with a coin placed next to one yuan with a diameter of about an inch.)
After folding the paper detector, CDs nanoparticles bind to the analyte, which leads to the convergence of the two types of nanoparticles. At the final stage, the researchers add a solution of hydrogen peroxide to the space between the folded pieces of paper, as a result of which the emission radiation excites CDs nanoparticles, and an electric current appears, which goes through the electric circuit to the supercapacitor, and its strength increases.
The researchers from the Yu group tested their device on human serum samples, into which they added various amounts of adenosine triphosphate (ATP); the tests showed that the minimum concentration of ATP that can be determined using the new device is 0.2 picomol/L. Yu adds that the analysis of one sample takes 10 minutes, and the cost of manufacturing such a device is 10 cents.
Portal "Eternal youth" http://vechnayamolodost.ru27.03.2013