In DPV Bard & Faulkner suggest that the surface concentration of analyte is regarded as the apparent bulk concentration of the pulse, suggesting that surface confined electrochemistry is not as important to identify in DPV as in CV . The peak separation of Zn Porph was found to be 56 mV, indicating a fast, reversible two-electron transfer event in CV, but this may not be the case in DPV measurements. ΔEp and the size of the AuNPs appears to exist, with an increase in ΔEp observed as the size of the AuNPs increases suggesting slower electron transfer kinetics , except for the case of 100 nm AuNP-MUA-Cyt c/Zn Porph Ox Electro. This correlation between the size of AuNPs and the ΔEp of Cyt c conjugated to them could be the result of the quantity of AuNPs in the samples, as there is an overall greater surface area of Au in the AuNP samples utilising smaller AuNPs. The electronrich AuNPs may therefore help mediate the reversibility of Cyt c, this is supported by work which has shown that AuNPs can act as electrocatalysts . Another perspective is that the correlation between the size of the AuNPs and the ΔEp of Cyt c may be due to the number of AuNPs in the sample. The multifunctionalised AuNP samples were normalised for Cyt c concentration, and the smaller AuNPs have less Cyt c per individual AuNP, therefore, there are more AuNPs in the solution compared to the larger AuNPs and so there is a greater chance of a portion of the AuNPs being surface confined. However, as previously stated, the concertation of analyte at the surface of the electrode is regarded as the bulk concentration , so may not influence the ability to determine the kinetics of the electrons moving between the multifunctionalised AuNPs and the electrode.