From Longman Dictionary of Contemporary Englishnot one/an iotanot one/an iotaNONE/NOTHINGnot even a small amount SYN bit It won’t make an iota of difference. → iota
Examples from the Corpus
not one/an iota• We have heard not one iota of evidence or heard any defense the suspect may have in this case.• It was none of her business and it mattered to her not one iota.• There is not an iota of evidence that such standardised testing has improved education anywhere in the world. 