Yong Chen, Jiye Cai, Meili Liu, Gucheng Zeng, Qian Feng, Zhengwei Chen*

Department of Chemistry, Jinan University, Guangzhou, Guangdong, P. R. China; *Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA

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Summary: Information obtained by atomic force microscopy (AFM) depends strongly on the kind of probe or tip used; therefore, probe and tip effects have to be taken into account when verifying or interpreting the data acquired. In many papers, double-tip effects have been mentioned while other research was done; however, there are only a few special reports on double- or triple-tip effects, especially double-probe effects. In our paper, metaphase chromosomes of Chinese hamster ovary (CHO) cells, aggregates of pectin molecules, membrane surface of mouse embryonic stem cells, and R-phycoerythrin-conjugated immunoglobulin G complexes were imaged by AFM with high-quality probes, double-probe cantilever, and double-tip and triple-tip probes, respectively, in order to determine double-probe, double-tip, and triple-tip effects during AFM scanning. We found that the double-probe, double-tip, and triple-tip effects share the same principle, and that these effects correlate with distance and height differences between probes of double-probe cantilever or tips of double-tip or multiple-tip probes. Since many other factors influence double-probe or double-tip effects, more in-depth studies must be undertaken. However, this initial research will make all users of AFM techniques aware of double-probe and double-tip or triple-tip effects during AFM scanning and aid in verifying or interpreting the data acquired.

Key words: double-probe effects, double-tip effects, triple-tip effects, atomic force microscopy, tip artifacts, chromosome, pectin, phycoerythrin conjugated immunoglobulin G

PACS: 07.79.-v, 07.79.Lh

This work was supported by grants from the National 973 Programs of China (No. 2001CB510101), National Natural Science Foundation of China (No. 62078014), the Key Program of National Natural Science Foundation of China (No. 30230350), the NIH of USA (HL64560), and the Doctoral Start-up Foundation of Jinan University.