Changes

LxUs is a team from the Uppsala University of Lisbon competing in the SensUs 2019 event. For SensUs 2019, LxUs investigated the possibilities for creating a biosensor which is able to measure the concentration of [[Adalimumab]]. The full TRD can be found [ via this link]

changes in optical properties of the 60 nm dimater Au-NP, functionalized with anti-ADL antibodies, asthey bind to ADL.The Au-NP solution is contained in a plastic cuvette allowing an easy and fast mix of nanoparticlesand plasma. The detection system is comprised of a 405 nm laser, as the light source, and a photodiodeas a detector, allowing for the transduction of the light transmitted through the cuvette into an electricsignal. This signal is then amplified, processed and fed into an Arduino board with a Bluetooth modulestreaming of the results to a smartphone application that displays and records them for future monitoring.

The LxUs biosensor working principle is the measurement of changes in the optical properties of asolution of gold nanoparticles (Au-NP) functionalized with biotin as they bind to Adalimumab (ADL)molecules. These changes are proportional to the concentration of ADL. The absorbance peak of Au-NPshifts to higher wavelengths as the particles bind to a ligand (the ADL) [1–3], increasing their radius. Byincreasing or decreasing the concentration of ADL, the absorbance value changes proportionally.For this purpose, Au-NP, 60 nanometre diameter, pegylated (PEG 5000) and biotin terminated,were employed (Sigma-Aldrich, product code 808911) together with anti-ADL antibodies for molecularrecognition. For assays, lyophilized human plasma (Sigma-Aldrich, product code P9523) and anti-TNF-/alpha (Adalimumab) (Biovision Incorporated, catalog number A1048) were used.

present in the sample. For that, a collimated laser diode (Thorlabs, part number CPS405) with a 405nm wavelength is used with a corresponding photodiode. The beam crosses a cuvette (Sigma-Aldrich,product code C5291) containing the sample and the transmitted intensity is then converted to an electricpotential by the photodiode. This signal is amplified by a negative-feedback amplifier circuit, sent toan Arduino UNO board and the corresponding sample concentration transmitted via Bluetooth to asmartphone application. Schematic of the device apparatus is show in figure 1.The measured values allow calculation of the sample’s concentration of ADL bound to the Au-NP.Obtaining data in order to create a calibration curve enables the computation of the sample’s ADLconcentration on the Arduino UNO board.

Regarding the handling of the fluid, other than the test tubes and the micropipette’s tip, we optedfor the usage of polystyrene Polystyrene cuvettes (Sigma-Aldrich, product code C5291) with two polished windowsfor the light measurement step, placed in a cuvette holder.

To ease the interaction between user and device, an intuitive smartphone application was created.It allows creation of patient profiles and storage of their respective test results. As such, any Android smartphone can be used as a reader instrument for the LxUs biosensor. The application was developedusing OutSystems. Communication with the biosensor is performed via Bluetooth, namely a moduleconnected to the Arduino UNO board.The user needs only to insert a small cuvette containing the solution of plasma, Au-NPs and ADL inthe equipment. By pressing a button in the application, the ADL concentration is shown on the screen.When the application is accessed, the main screen presents three options: New Patient, Patient List,New Analysis.The “New Patient” screen allows you for the user to create a new profile. Once you have the user has finished filling your out the newpatient’s profile out, just they can click save to add it to your the Patient Profile List.The “Patient List” screen lists all the patient profiles you have the user has created so far. Clicking on one of thenames opens the Patient Profile of your choice, providing you the user with even more options. If you click the“More Details” optionis clicked, you the user will be shown the most important information of your the patient’s data.The “New Analysis” option takes you the user to a screen which allows communication with the LxUs biosensor.In there, you are The user will then be able to turn on the Bluetooth of your their mobile device and begin the sample analysis bysimply pressing a button. Once the sample testing finishes, the results will be shown on the screen.