Compound characterization data — Zhou and Bizzotto, 2026

Geyang Chris Zhou, Dan Bizzotto. “A coupled redox and fluorescence study of carbodiimide conjugation of DNA to 11-mercaptoundecanoic acid SAMs on Au.” ChemRxiv (2026). https://doi.org/10.26434/chemrxiv.15007548/v1

50:50 11-MUA/MUDOL SAM on a single-crystal gold bead electrode after 20:80 mM sNHS/EDC activation for 20 min in MES (pH 5.8), 1 h conjugation with 0.1 µM amine-functionalized ATTO655-labelled DNA in 0.01× PBS, and overnight storage in 1 mM Tris buffer (pH 7.4)
Identifier	NH2DNA655
CV (10, 20, and 50 mV s⁻¹), midpoint potential	Approximately −0.41 V/SCE at all three scan rates
CV (10 mV s⁻¹), coverage reported as ΓATTO665 from reduction-peak integration	2.0 pmol cm⁻²
Coverage-derived separation reported by the authors if uniformly distributed	98 Å, 9.8 nm
CV, ΔEp over 10–50 mV s⁻¹	18–48 mV
CV (10 mV s⁻¹), peak width	72 mV FWHM
SWV (1–17 Hz), Epeak	−0.41 V/SCE
SWV, frequency-normalized peak current	No maximum was observed over 1–17 Hz; the authors estimated a redox rate <1 s⁻¹
Fluorescence imaging at 0 V/SCE	All electrode regions fluoresced; the center was consistently dimmer; the 111 facets and four regions around 100 had higher intensity
In-situ fluorescence during negative potential steps	Intensity began decreasing at −0.35 V/SCE and was minimal at −0.7 V/SCE, where all redox-active ATTO655 was reduced
In-situ fluorescence, effective sweep rate; hysteresis	Approximately 2 mV s⁻¹; little to none between reduction and oxidation
Mean fluorescence intensity	Appeared as a sigmoid centered at E° of ATTO655 and changed from maximum to minimum within 100 mV at the slow effective sweep rate

100 % 11-MUA SAM on a single-crystal gold bead electrode
111-facet reductive desorption in 0.1× PBS	−0.8 V/SCE

50:50 11-MUA/MUDOL SAM on a single-crystal gold bead electrode
111-facet reductive desorption in 0.1× PBS	−0.9 V/SCE

Alkylthiol SAM on a single-crystal gold bead electrode
Identifier	MCH
111-facet reductive desorption onset in imaging buffer (10 mM Tris, 10 mM KNO3, approximately pH 7.4)	−0.6 V/SCE

50:50 11-MUA/MUDOL SAM on a gold electrode after 20:80 mM sNHS/EDC activation for 20 min and exposure to 0.1 µM amine-functionalized ATTO655-labelled DNA in 0.1× PBS for 20 min
Identifier	NH2DNA655
CV (10 mV s⁻¹, −0.1 to −0.7 V/SCE), estimated coverage	2.3 pmol cm⁻²

50:50 11-MUA/MUDOL SAM on a gold electrode after 20:80 mM sNHS/EDC activation for 20 min and exposure to amine-functionalized ATTO655-labelled DNA in 0.1× PBS for 20 min
Identifier	NH2DNA655
CV (10 mV s⁻¹, −0.1 to −0.7 V/SCE), estimated coverage	2.1 pmol cm⁻²
Redox-linked fluorescence change	Slightly larger than for the lower-concentration example, primarily because of heterogeneous high-intensity regions
Redox charge compared with the lower-concentration example	No impact within ±10 %

50:50 11-MUA/MUDOL SAM on a gold electrode after 20:80 mM NHS/EDC activation for 20 min and exposure to amine-functionalized ATTO655-labelled DNA in 0.1× PBS for 20 min
Identifier	NH2DNA655
CV (10 mV s⁻¹, −0.1 to −0.7 V/SCE), estimated coverage	0.08 pmol cm⁻²

50:50 11-MUA/MUDOL SAM on a gold electrode after 20:80 mM sNHS/EDC activation for 20 min and amine-functionalized ATTO655-labelled DNA exposure
Identifier	NH2DNA655
Coverage estimated by integration of the 10 mV s⁻¹ CV redox peak	2.1 pmol cm⁻²

50:50 11-MUA/MUDOL SAM on a gold electrode after 50:200 mM sNHS/EDC activation for 20 min and amine-functionalized ATTO655-labelled DNA exposure
Identifier	NH2DNA655
Coverage estimated by integration of the 10 mV s⁻¹ CV redox peak	3.0 pmol cm⁻²

50:50 11-MUA/MUDOL SAM on a gold electrode after 50:200 mM sNHS/EDC activation for 120 min and amine-functionalized ATTO655-labelled DNA exposure
Identifier	NH2DNA655
Coverage estimated by integration of the 10 mV s⁻¹ CV redox peak	5.8 pmol cm⁻²
Coverage-derived values reported by the authors	Approximately 3.5 × 10¹² DNA cm⁻²; approximately 5.8 nm average distance between neighboring DNA molecules
Fluorescence distribution	Nonuniform; the 111 facet appeared to have higher DNA coverage
CV	Distorted and deviated from ideal
Fluorescence response during ATTO655 reduction and oxidation	Noticeably faster on 110 and 311 regions than on 111 and 100 regions

Unactivated 50:50 11-MUA/MUDOL SAM exposed to 1 µM amine-functionalized ATTO655-labelled DNA in 0.1× PBS for 1 h
Identifier	NH2DNA655
Adsorption, redox, and fluorescence	No nonspecific adsorption and no redox or fluorescence were observed

50:50 11-MUA/MUDOL SAM on a gold electrode after 20:80 mM sNHS/EDC activation in 100 mM MES (pH 5.8) and 1 h exposure to 0.1 µM amine-functionalized ATTO655-labelled DNA in 0.01× PBS for the cadaverine comparison
Identifier	NH2DNA655
CV-derived coverage reported by the authors	2.8 pmol cm⁻²
Fluorescence during ATTO655 reduction	Intensity decreased

50:50 11-MUA/MUDOL SAM on a gold electrode after 20:80 mM sNHS/EDC activation in 100 mM MES (pH 5.8) and 1 h exposure to 0.1 µM ATTO655-labelled cadaverine in 0.01× PBS
Identifier	CAD655
Fluorescence from 0 to −0.7 V/SCE	Background level; no detectable ATTO655
CV (10 mV s⁻¹)	No redox peak above the capacitive background
SWV	No signal above background and no redox features

50:50 11-MUA/MUDOL SAM on a gold electrode after 20:80 mM sNHS/EDC activation in 100 mM MES (pH 5.8) and exposure to 10 µM ATTO655-labelled cadaverine in 1× PBS for 1 h
Identifier	CAD655
CV, surface-bound faradaic peaks; shoulder peaks	Centered at approximately −0.39 V/SCE; centered at approximately −0.48 V/SCE
Estimated coverage	Approximately 11 pmol cm⁻²
SWV, author-estimated kET	Approximately 10 s⁻¹

50:50 11-MUA/MUDOL SAM on a gold electrode after 20:80 mM sNHS/EDC activation in 100 mM MES (pH 5.8) and exposure to 10 µM ATTO655-labelled cadaverine in 1× PBS for 3 h
Identifier	CAD655
Estimated coverage	Approximately 30 pmol cm⁻²
CV and SWV	Nonideal CV peak shapes; the authors reported a nonuniform distribution in kET
Fluorescence intensity compared with the lower-coverage DNA SAM	Much smaller

Activated 50:50 11-MUA/MUDOL SAM after exposure to ATTO655-labelled 50-mer DNA lacking the primary amine
Identifier	DNA655
CV-derived coverage before heating	Approximately 1.2 pmol cm⁻²
Response compared with the amine-terminated NH2DNA655 interface	Similar, with the NH2DNA655 interface having roughly double the coverage
After 1 h at 50 °C and 1 h at 55 °C in 1× PBS	Redox charge decreased by approximately 90 % and fluorescence intensity by 60 %; not all nonspecifically adsorbed DNA was removed
Fluorescence distribution during heating	The intensity pattern seemed random, and the decrease did not appear related to the underlying surface crystallography

Separately activated 50:50 11-MUA/MUDOL SAM after exposure to ATTO655-labelled 50-mer DNA lacking the primary amine and soaking in Tris
Identifier	DNA655
10 mM Tris soaking	Nonspecifically adsorbed DNA655 was removed after up to 7 h

50:50 11-MUA/MUDOL SAM conjugated with amine-functionalized ATTO655-labelled DNA after heating at 55 °C for 1 h in 1× PBS
Identifier	NH2DNA655
Capacitance	Unchanged, with no evidence of thiol loss
Redox and fluorescence	Heating seemed to improve DNA organization and resulted in more redox-active DNA, though with a smaller fluorescence change

50:50 11-MUA/MUDOL SAM conjugated with amine-functionalized ATTO655-labelled DNA during reductive desorption
Identifier	NH2DNA655
CV (10 mV s⁻¹), coverage	2.2 pmol cm⁻²
Underlying 11-MUA/MUDOL SAM reductive desorption potential	−0.92 V/SCE
Capacitance (5 mV rms, 200 Hz)	Approximately 2 µF cm⁻² from −0.1 to −0.9 V/SCE; increased beyond −0.9 V/SCE; at the most negative potentials it may be artificially increased by HER under the simple-RC assumption
SAM stability	Stable to −1.0 V/SCE
Fluorescence	ATTO655 was fully reduced by −0.7 or −0.8 V/SCE; the SAM was not significantly disturbed until −1.0 V/SCE
Facet-specific desorption	111 facets desorbed first at Estep = −1.09 V/SCE, followed by 100 at Estep = −1.36 V/SCE; removal was complete at −1.5 V/SCE
Fluorescence at −0.96 and −1.55 V/SCE	Very similar and at background levels for the fully reduced and fully desorbed states
Ebase fluorescence after Estep < −1.25 V/SCE	Fluctuated; the authors attributed this to readsorption and drift of desorbed species
Ebase fluorescence	Decreased only after complete desorption at E < −1.5 V/SCE

Activated 50:50 11-MUA/MUDOL SAM with nonspecifically adsorbed ATTO655-labelled 50-mer DNA during reductive desorption
Identifier	DNA655
CV-derived coverage, SI	Approximately 0 pmol cm⁻²
CV and slower potential-step fluorescence	No CV peak was observed; fluorescence showed that ATTO655 was redox active during the slower potential-step measurement
Fluorescence from −0.1 to −0.4 V/SCE	Intensity began decreasing as soon as a negative potential was applied
Underlying SAM stability	Stable until −0.9 V/SCE
Fluorescence at Estep and Ebase	Both decreased monotonically as Estep became more negative
Removal	Nonspecifically adsorbed DNA655 was removed with the alkylthiol in a crystallographically specific manner

50:50 11-MUA/MUDOL SAM conjugated with amine-functionalized ATTO655-labelled DNA and equilibrated with complementary DNA
Surface-DNA identifier	NH2DNA655
Complement identifier	cDNA
Initial CV-derived coverage	2.7 pmol cm⁻²
Frequency-normalized SWV (1 Hz), after equilibration with 0.1–100 nM cDNA	Decreased significantly after hybridization
Sipps-isotherm fit reported by the authors, Kd; coefficient	8 nM; 2.5

50:50 11-MUA/MUDOL SAM conjugated with amine-functionalized ATTO655-labelled DNA after initial Milli-Q-water heating, two 1 h hybridizations with 100 nM cDNA, and 15 min Milli-Q-water heat treatments from 25 to 55 °C
Surface-DNA identifier	NH2DNA655
Complement identifier	cDNA
Fluorescence intensity and redox-charge-derived coverage	Decreased; the authors attributed the decrease to a combination of loss of nonspecifically adsorbed NH2DNA655 and denaturation of double-stranded DNA