| Because of the constant improvements in biological detection field,as well as the popularization of biological products,the biological detection becomes more and more demanded and important.Biological detections include fields such as food safety,medicine and health and so on.This article's research includes two parts,and three innovation points.The first part investigates the applications of Raman Spectroscopy and ultra-weak photon emission in the detection and monitoring of pork freshness.Their advantages and disadvantages are compared and analyzed.We discovered that Raman spectroscopy can quickly and precisely detect the spectral changes which happen during pork's storage;the reduced intensity of 1650cm-1 Amide I peak shows the spoilage of pork at room temperature.On the other hand,the Raman peaks of pork stored at 4 degrees Celsius is not changed significantly.Thus,the change in Raman peak intensities can show the change in pork freshness.Raman spectroscopy is more versatile,but the spectrometer itself is more expensive.Biological ultra-weak photon emission is another method that can detect the changes which happen during pork's storage.Its delayed luminescence curve can be simulated and the related indices can be obtained,and this method is practical for the mass inspection of pork.The single photon counting system is relatively easy to make,but its operation environment needs to be strictly controlled.However,neither methods can satisfy the needs for all types of biological detections,because both methods produce weak signals.Thus,another,more in-depth method is investigated in this article,and that is Surface Enhanced Raman Spectroscopy?SERS?.The second part involves research on SERS the detection of trace matter,and performs SERS measurement on human blood serum.First,a type of optimized SERS substrate is produced.The method is using ultra-violet light to reduce silver nitrate in the presence of titanium dioxide.It has good enhancement factor,uniformity and longevity.The optimal production method and conditions was found by measuring Rhodamin 6G;SEM was used to observe its surface structures;ellipsometer was used to check the thickness of the titanium dioxide layer and optimize enhancement performance.Finally,the optimal method involves coating a layer of titanium dioxide on quartz slide with dip coating speed from 180 to 230mm/min,and then calcinate it at 450 to 550 degrees Celsius for 60minutes,and then let it rest in silver nitrate solution illuminated by filtered 254nm UV light.The substrate produced by this method can be used to detect 10-8M R6G.Then,this SERS substrate is used to categorize different types of serum:serum from healthy individuals,and serum from lung cancer patients.However,serum added to the substrate by dropping cannot produce effective Raman signals;such a method would be affected by photo-degradation and the signals are damaged.However,serum could be diluted using normal saline,then immerse the substrate in the diluted serum solution.The resulting sample could produce good serum SERS signals with 785nm laser.The method is used on 187 serum samples.The resulting classification accuracy was 82.9%using factor analysis with discriminant model,and82.4%for cross validation.We also used principle component analysis in conjunction with support vector machine model,and got a 90%correct classification result.This means different categories of serum could be classified.The innovation points are as follows:1)Innovation on pork freshness detection and measurement;2)innovation on the production of SERS substrates;and 3)innovation on serum classification. |
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