Thiol-modified DNA self-assembled monolayers (SAMs) on gold is the ideal heterogeneous system for studying DNA charge transfer through DNA duplex, designing DNA sensor with high sensitivity and identifying single base mismatch etc. The performance of DNA SAMs on gold is related to three aspects: gold surface conditions, DNA characteristics and surroundings. Gold surface conditions mainly include substrate configuration by different surface pretreatment, gold shapes, substrate potential and substrate temperature; DNA characteristics include the difference of double-stranded and single-stranded DNA, DNA base types, types for thiols modification and factors related to DNA electron transfer; Surroundings mainly include ionic strength or types of cations, ambient medium, temperature in solution and types of mixed thiols. These factors influence surface density and conformation of DNA SAMs on gold, which determine its charge transfer or hybridization performance. In order to controllably construct DNA SAMs with the optimal performance for satisfying different researches about DNA, it is very necessary to understand the effect of different factors on the performance of DNA SAMs on gold. In this article we review the research progress of influence factors on the performance of DNA SAMs on gold from three aspects including gold surface conditions, DNA characteristics and surroundings.

Contents
1 Introduction
2 Gold surface conditions
2.1 Surface pretreatment
2.2 Gold substrate shapes
2.3 Gold substrate potential
2.4 Gold substrate temperature
3 DNA characteristics
3.1 Double-stranded and single-stranded DNA
3.2 DNA base types
3.3 Types for thiols modification
3.4 Factors related to DNA electron transfer
4 Surroundings
4.1 Ionic strength and types of cations
4.2 Ambient medium
4.3 Temperature in solution
4.4 Types of mixed thiols
5 outlook