Zeta-potential measurements before and after CPP attachment to silica particles, their maximum absorption values, and concentration of attached CPPs on the particle surface as determined by Bradford assay. Absorption maxima for CPP-functionalized particles of 300 nm diameter could not be determined due to the strong scattering of the particles and the low concentration of attached CPPs.

Sample	ζ-Potential before CPP attachment [mV]	ζ-Potential after CPP attachment [mV]	Lambda max [nm]	Concentration of the CPP [μM]
50-HK3	−28.3 ± 0.6	5.0 ± 0.1	498	25.28
50-HK15	−28.3 ± 0.6	12.0 ± 0.8	498	27.95
50-HK17	−28.3 ± 0.6	9.1 ± 0.1	498	28.33
150-HK3	−29.3 ± 0.6	4.4 ± 0.8	501	19.33
150-HK15	−29.3 ± 0.6	22.0 ± 0.4	500	17.78
150-HK17	−29.3 ± 0.6	10.9 ± 0.6	501	22.82
300-HK3	−29.9 ± 0.2	6.0 ± 0.3	—	12.68
300-HK15	−29.9 ± 0.2	9.8 ± 1.3	—	13.13
300-HK17	−29.9 ± 0.2	7.3 ± 1.0	—	10.77