Research On Detection Technology Of Quartz Crystal Microbalance Based On The Effect Of Crystal Mass Increase

To enhance the sensitivity of QCM for the detection of bioactive molecules,in-situ selective crystallization based QCM was constructed.Self-assembled film were described and studied in a lot of researches,the property of self-assembled film in controlling crystallization has a mature theoretical basis,and shows great performance in practical application.In our experiment,we control the crystallization of calcium carbonate mainly by the exposure of functional groups.In our strategy for signal amplification,we choose –N(CH3)3 and –COOH,where –N(CH3)3 group was applied as a nucleation blocker and –COOH group as an enhancer.With the combination of the two functional groups,it realized the control of in-situ selective crystallization of calcium carbonate on the sensor,and it provided the possibility for signal amplification.We have studied and compared the other common method for detecting tumor markers and the other signal amplification technology based quartz crystal microbalance(QCM).By contrast,the in-situ selective crystallization based on QCM strategy is principle-simple,biobarcode-free,ultrasensitiveand selective,and showed a promising prospect in early disease diagnosis.The main contents of this study are as follows:1.Surface crystallization of CaCO3 on gold was monitored by quartz crystal microbalance(QCM).Quantitative control of the grown crystals was realized by adjusting the ratio of two functional groups,-N(CH3)3 and –COOH.Crystals with uniform size,morphology and polymorph were obtained.The amount of crystals was found to regularly increase with the composition of –COOH group.It is proved that the proposed quantitative control of crystallization can be an effective mass amplification strategy for QCM to enhance its assay sensitivity.2.As a mass amplification strategy,the in-situ selective crystallization system significantly enhanced the QCM signal for more than thousands folds,and improved the sensitivity of QCM for DNA detection.A detection limit of 2aM and a wide linear range from 10 aM to 1nM are achieved for DNA.The perfect matched DNA was discriminated from 1-base mismatched DNA with high selectivity and this strategy can applied to the detection of single nucleotide polymorphisms.3.The selective crystallization based QCM platform is of satisfactory performance when it used to DNA detection.In order to expand its detection field,we hope it can be used for cell detection.In our study,we choose the Ramos cells as detection target.Based on the combination of introduction of aptamer and the in-situ selective crystallization system,the detection of Ramos cells are also realized with a LOD of 5 cells per milliliter and a linear range of 5 cells per milliliter to 6000 cells per milliliter.Finally,the performance of QCM based on different mass amplification strategy as DNA and Ramos cell sensor is summarized.By contrast,the in-situ selective crystallization based QCM strategy is with high sensitivity.4.We made a summarisation of in-situ selective crystallization based QCM strategy and an analysis of its promising prospect.This study provides a new view and new ideas for QCM.Based on this strategy,a general platform to test all kinds of bioactive molecules can be build,and we believe that with the researchers' further study,this strategy can be truly applied in the clinical diagnosis and treatment.Furthermore,it showed a promising prospect and great hope for early disease diagnosis.