Research On Biosensing Properties Of Nanofilm Modified Long Period Fiber Grating

Biosensors not only promote the rapid development of biotechnology in the 21 st century,but also play an increasingly important role in medical diagnosis,environmental monitoring,biometrics,homeland security and national defense construction.The research of new biosensors has become one of the cores to promote the development of biotechnology.Based on the coupling-mode theory of single-mode long-period fiber grating,a nanofilm-modified long-period fiber grating biosensor for biomolecule concentration measurement is proposed.The recognition biomolecule is covalently immobilized to the surface of long-period fiber grating through the combination of chemical bonds,and then the recognition biomolecule interacts with the biomolecule that is waiting for detection to produce immune complexes that effect resonance peak of nanofilm-modified long-period fiber grating biosensor.Using this phenomenon can achieve the detection of biomolecule concentration.The specific research contents are as follows:Firstly,the basic knowledge of long-period fiber grating,biological sensing and free-label optical biosensors is introduced.The numerical analysis is carried out on the effective refractive index,coupling coefficient and transmittance of long-period fiber grating.In addition,the refractive index sensing characteristics about long-period fiber grating and the influence of nanofilm-modified thickness to long-period fiber grating is discussed.Secondly,the system structure of nanofilm-modified and free-label long-period fiber grating biosensor is designed.And then the methods on biomolecule immobilization,the influence conditions and characteristics of immune reaction are discussed in detail.That will lay the theoretical basis for the next grating biosensor experiments.Thirdly,based on the theory of nanofilm-modified sensing,the experimental procedures and principles of pre-chemical treatment about free-label long-period fiber grating biosensor are introduced in detail,and the experimental results and its reasons for this phenomenon are also detailed analyzed.Finally,the experimental procedures about the recognition biomolecule immobilization and the concentration measurement of target biomolecule are detailed described.The experimental platform is set up and the quantitative measurement of the biomolecule concentration is completed.The maximum concentration sensitivity of the sensor is 2101.5dB/mg/m L,and the measurement of the rabbit IgG molecule with the minimum concentration of 0.0003125mg/mL is realized.