Establishment Of Paper-based Ion Concentration Polarization Interface And Its Application In The Processing And Detection Of Salty Samples

The paper-based analysis device(PAD)has become a platform for chemical and biomedical analysis due to its low cost and simple processing.The pretreatment of biological samples with complex compositions and low contents of some target components plays a key role in the reliability of instrumental and point-of-care testing results.Based on the ion concentration polarization(ICP)effect on the micro-nano interface as an electrokinetic stacking method,it can effectively enrich the charged components in complex media,thus becoming an important method for sample purification and improvement of analytical sensitivity.In order to improve the detection ability of the paper-based analysis device,it is of great significance to combine the ion concentration polarization effect with the paper-based analysis device,and is also necessary to investigate the salinity tolerance of this method to make it suitable for the analysis of target components in salty media.The first chapter introduces the principle and development status of common sample pre-concentration methods,as well as the processing methods of salty samples.The commonly used detection methods in paper-based analysis devices and their applications in various fields were also introduced.Chapter 2 introduces a new type of simple and reliable crossing concentration polarization interface,and successfully demonstrates the electrokinetic stacking of target components in salty media.The established interface still exhibits a significant ion concentration polarization effect under medium conditions of up to 400 mmol/L NaCl,which provides a basis for the direct processing of salty clinical samples such as blood and urine.Application of this method was demonstrated by direct online stacking of total protein from urine samples and image based colorimetric detection by smartphone camera.The dynamic range is 10～400 mg/L and the linear response was in the range of 50～350 mg/L(R2=0.99),with recovery rate in the range of 94.8～107.6%and RSD is less than 7.1%.The obtained results were consistent with that of the clinical method.Chapter 3 introduces the first successful combination with the serum sample at the crossing ion concentration polarization interface,and the feasibility of this method is verified by using phycocyanin as the probe.As an off-line analysis method,the paper-based analysis device is combined with an UV-visible spectrophotometer to achieve the successful detection of phycocyanin in the dry serum sample.The recovery rate reached 80.1%.In the actual sample detection,the method was combined with a more advanced tandem mass spectrometry(MS)to achieve the determination of 9 common amino acids in serum.The RSD of the three parallel tests were all below 5%,and the results showed that all amino acids except phenylalanine are within the normal range.The feasibility of loading blood samples in the form of dry paper samples combined with PAD ICP interface for sample cleanup and offline MS rapid detection was confirmed.