Abstract: The present invention provides a novel virus-like particle expression vector pTMSCA2C, which is constructed as follows: firstly, using plasmid pTrcHis-MS2 as a starting vector and mutating the base T at position 5 of the gene sequence of MS2 bacteriophage 19mer packaging site on the plasmid pTrcHis-MS2 into C through genetic mutation technologies to obtain a plasmid pTMSC; then, mutating valine which is a amino acid corresponding to the initiation codon on the plasmid pTMSC for encoding the maturase protein of MS2 bacteriophage into methionine to obtain a plasmid pTMSCA; and finally, the gene sequence coding wild type MS2 bacteriophage coat protein, after the removal of the terminator, is linked in series with the gene sequence coding MS2 bacteriophage coat protein comprising histidine-tag which is from a pseudovirus vector pTrcMS, and the gene sequence obtained after linking in series is linked to the plasmid pTMSCA to give pTMSCA2C.

Abstract: A method for detecting biological markers involves preparing sample slices using a hard granular labeling material such as hard nano-gold granular material. The sample slices are fixed to sample patches. The sample is scanned using the atomic force microscope (AFM) in tapping mode to collect the height, amplitude and phase data of the hard granular material. The hard labeling material is mainly determined through changes in discrepancies in phase diagram color, while height and amplitude diagrams are used to provide auxiliary evidence of sample morphological features. Integrating these data with the state of the biological target object can thus determine the existence of a marked object.