Study Of A Protable Angle-interrogation Surface Plasmon Resonance Biosensor

Surface plasmon resonance(SPR)sensor is a kind of optical sensor which can be used for detecting the change of biological or chemical reaction.SPR can detect biological macromolecule interactions(proteins and proteins,proteins and DNA,DNA and DNA,etc.),and has a wide range of applications including medical diagnose,environmental monitoring,food security and other fields.Traditional detection methods(such as ELISA,RIA,etc.)have disadvantages of hard to operate,labeling,time-consuming and large sample consumption.On the contrary,based on the advantage of label-free,real-time detection and low sample consuming,SPR sensor had become one of the research hotspots in the field of biological and chemical sensor.Since the 1980 s,relative studies on the role of SPR in the detection of biochemical molecules have gradually increased abroad.At present,there are some commercially available SPR sensing instruments.In domestic,research on SPR sensor appeared later but it also attracted more and more attention.Most of existing SPR sensors are large in size and are not easy to carry.They are sensing platforms which are only suitable for the laboratory research.It is important to study and develop a small portable SPR biosensor for its convenient application in in-site detection and clinical testing.The purpose of this paper is to develop a small and portable SPR sensor based on the angle modulation mode.The following aspects are designed to realize the miniaturization of the instrument.First,in order to achieve certain detection accuracy,the detection mode of the SPR sensor is angle modulation,and wedge-shape structure is used to get multi-angle light beam instead of the conventional equipment for getting varying angle.Second,cutting down the light path and the use of lenses can focus the divergence light beam to one point at a quite short distance to converge parallel light beam.The third is the choice of light source.Considering both small volume and stable performance,semiconductor laser is adopted as light source.Fourth,irregular quadrangle prism is attempted to use to realize light source and detector in the same direction,which is helpful to narrow the total volume.In this paper,the design of optical path and the establishment of the miniature SPR sensor detection device model are firstly carried out.MATLAB simulation software is used to confirm the important SPR instrument parameter,including prism material,thickness of articulamentum(Cr)and metal film,and the material of metal film.Then,an attempt is done to design irregular quadrangle prism to set up the experiment platform,and several tests are conducted both in air and liquid phase.The test shows that the irregular quadrilateral prism cannot meet the requirements of the liquid phase environment detection and facilitate the mechanical fixation and carrying.So finally semi-cylindrical prism is adopted to carry out small SPR sensor equipment.The size of the prototype of the instrument is 290 mm(L)×190 mm(W)×130 mm(H)and the net weight is 3 kg.The design of flow cell,which is the guarantee of successfully and rapidly experiment,is also a key step in the experiment.The flow cell is designed to achieve two goals,no leakage and low sample consuming.In this paper,PMMA plate combined with Si rubber gasket is presented to construct the flow cell.The silicone rubber gasket has good sealing property,which is helpful for closely fitting chip and PMMA,as well as avoiding the leakage phenomenon.At the same time,the flow cell size is limited as 10 mm(L)×1 mm(W)×1 mm(D)for low sample consumption.After completion of the small SPR sensor instrument,the secondary development of data acquisition interface is realized.After the secondary development,acquisition interface can detect light intensity of different pixel at the same time and a fixed pixel vs.time.In this interface,the function of data processing is also achieved by combining VC++ and MATLAB including lots of built-in functions.This way makes it more efficient.Performance of the established miniaturized SPR sensor is tested.Firstly,different concentrations of ethanol solution are prepared for instrument calibration and analyzing the sensitivity.Then the stability,repeatability and linearity are analyzed with BSA experiment.The linearity result of ethanol solution and BSA is 0.9766 and 0.9907 respectively.Sensitivity is 10-4 RIU.In the Ig G specific adsorption experiment,the concentration of substrate IgG is 1 mg/mL,which is fixed on the interface of a sensor chip.The detection limit of Anti-IgG is as low as 0.025 mg/mL.When replacing substrate IgG with BSA,there is no obvious sensor response for the same concentration.Within the saturation concentration,the sensor response of different concentration Anti-IgG is high linearity(R2 = 0.9977).