TY - JOUR

T1 - Charge balancing of model gold-nanoparticle-peptide conjugates controlled by the peptide's net charge and the ligand to nanoparticle ratio

AU - Gamrad, L.

AU - Rehbock, C.

AU - Krawinkel, J.

AU - Tumursukh, B.

AU - Heisterkamp, Alexander

AU - Barcikowski, S.

PY - 2014/4/17

Y1 - 2014/4/17

N2 - Gold nanoparticles (AuNPs) covalently bound to biomolecules, termed bioconjugates,1 are highly relevant for biological applications like drug targeting or bioimaging. Here, the net charge of the bioconjugate is one key parameter affecting biocompatibility and cell membrane interaction. However, when negatively charged AuNPs are conjugated to positively charged biomolecules, resulting charge compensation compromises the stability of the conjugates. In this work, laser-generated negatively charged AuNPs exhibiting a bare surface were used as a model and separately conjugated to cell penetrating peptides (CPPs) carrying different positive net charges. Occurring charge compensation leads to two regimes where stable bioconjugates are obtained on both sides of the bioconjugate's isoelectric point. These regimes can be controlled by the peptide's net charge. Generally, increasing the peptide's net charges yields stable positively charged bioconjugates with decreased surface coverages. To demonstrate the compatibility of the bioconjugates in bioapplications, long-term stability measurements were performed. Furthermore, the uptake by live mammalian cells was investigated with multiphoton microscopy using the luminescence of the AuNP-peptide conjugates. The results for our model system of laser-generated AuNPs and CPPs show that a precise tuning of conjugate properties is possible. They can be transferred to other oppositely charged nanoparticle-ligand systems, avoiding occurrence of charge compensation with defined ligand load.

AB - Gold nanoparticles (AuNPs) covalently bound to biomolecules, termed bioconjugates,1 are highly relevant for biological applications like drug targeting or bioimaging. Here, the net charge of the bioconjugate is one key parameter affecting biocompatibility and cell membrane interaction. However, when negatively charged AuNPs are conjugated to positively charged biomolecules, resulting charge compensation compromises the stability of the conjugates. In this work, laser-generated negatively charged AuNPs exhibiting a bare surface were used as a model and separately conjugated to cell penetrating peptides (CPPs) carrying different positive net charges. Occurring charge compensation leads to two regimes where stable bioconjugates are obtained on both sides of the bioconjugate's isoelectric point. These regimes can be controlled by the peptide's net charge. Generally, increasing the peptide's net charges yields stable positively charged bioconjugates with decreased surface coverages. To demonstrate the compatibility of the bioconjugates in bioapplications, long-term stability measurements were performed. Furthermore, the uptake by live mammalian cells was investigated with multiphoton microscopy using the luminescence of the AuNP-peptide conjugates. The results for our model system of laser-generated AuNPs and CPPs show that a precise tuning of conjugate properties is possible. They can be transferred to other oppositely charged nanoparticle-ligand systems, avoiding occurrence of charge compensation with defined ligand load.

UR - http://www.scopus.com/inward/record.url?scp=84900828059&partnerID=8YFLogxK

U2 - 10.1021/jp501489t

DO - 10.1021/jp501489t

M3 - Article

AN - SCOPUS:84900828059

VL - 118

SP - 10302

EP - 10313

JO - Journal of Physical Chemistry C

JF - Journal of Physical Chemistry C

SN - 1932-7447

IS - 19

ER -