Dbco oeg4 nhs

Poly-l-lysine hydrobromide (MW =
15–30 kDa by viscosity), poly(sodium 4-styrenesulfonate) (average
MW = 70 kDa), D₂O, and tablets for 10 mM PBS solution (pH
7.4, ionic strength of 150 mM) were obtained from Sigma-Aldrich. HCl
solution was obtained from SelectiPur. Methyl-OEG₄-NHS
ester was purchased from ThermoFisher Scientific, while DBCO-OEG₄-NHS was obtained from Click Chemistry Tools. The membranes
for dialysis (Spectra/Por, 6–8 kDa cutoff, diameter of 6.4
mm) were purchased from Spectrum Labs, Greece. The azide-DNA (MW,
7421 g/mol; 5′-N₃-PEG₄-ACCACAAGTTTATATTCAGTCAT-3′,
23 nt) was acquired from Biomers.net GmbH (chemical structure of the linker in Figure S1). cDNA (complementary to the KRAS sequence, 5′-ATGACTGAATATAAACTTGTGGTAGTTGGAGCTGGTGGCGTAG-3′,
43 nt) and ncDNA (5′-CTACGCCACCTCAACCTACGCCACCTCCACCTACGCCACCTC-3′,
42 nt) were purchased from Eurofins Genomics and used as received.

Poly-l-lysine hydrobromide (MW =
15–30 kDa by viscosity), NaClO₄, deuterated water,
and tablets for a 10 mM PBS solution (pH 7.4) were obtained from Sigma-Aldrich.
H₂SO₄ (95%) was purchased from VWR Chemical,
and HCl was obtained from SelectiPur. Methyl-OEG₄-NHS ester
was obtained from Thermo Fisher Scientific, while DBCO-OEG₄-NHS was obtained from Click Chemistry Tools. The membrane for dialysis
(Spectra/Por; 6–8 kDa cutoff; diameter, 6.4 mm) was purchased
from Spectrum Labs, Greece. cDNA (complementary to KRAS sequence: 43 nt, 5′-ATG ACTGAATATAAACTTGTGGTAGTTGGAGCTGGTGGCGTAG-3′)
and ncDNA (42 nt, 5′-CTACGCCACCTCAACCTA CGCCACCTCCACCTACGCCACCTC-3′)
were purchased from Eurofins Genomics and used as received. The ferrocene-labeled
DNA (23 nt; MW, 7487 g/mol; 5′-ACCACAAGTTTATATTCAGTCAT-Fc-3′)
was acquired from Biomers.net GmbH. Gold QCM chips (with a fundamental
frequency of 5 MHz) were purchased from Biolin Scientific. Silicon
p⁺⁺ wafers (⟨100⟩-oriented, one-side polished,
525 ± 25 μm substrate thickness, 0.01–0.025 Ω
cm resistivity) were obtained from Okmetic Finland, while the positive
Olin 907-17 photoresist was obtained from Arch Chemicals. The PNA
probe was synthesized using a previously described procedure.^{59 (link)}