Peptide-coated nanoparticles: Adsorption and desorption studies of cationic peptides on nanodiamonds

• Functionalization of carboxylated nanodiamonds by adsorption of cationic peptides.
• The adsorption and desorption behaviors of cationic peptides were determined.
• One to two shells of amphiphilic peptides are tightly adsorbed per mg of NDs.
• Stable cationic nanoparticles may be prepared by adsorption of adequately peptide.

The functionalization of nanoparticle surfaces remains a major challenge for broader applications in biology. To study the physisorption of peptides on nanodiamonds (NDs), we developed reliable and facile methods: UV titration, MALDI-TOF mass spectrometry or fluorescence spectrophotometry. These readily applicable procedures allowed us to analyze the adsorption and desorption behaviors of different cationic peptides. A rough estimate led to propose that an average of three to four shells of amphiphilic peptides rapidly adsorbed on NDs surface: about half of the molecules being adsorbed with a high affinity, while the other half may be exchanged within a few minutes. If a photoactivatable amino acid was incorporated in the peptide sequence, the subsequent irradiation allowed similarly the coating of three to five shells of peptides on the NDs surface, but in that case peptides were not exchangeable at all, even after a few days. Stable cationic nanodiamonds may be obtained by simple physisorption of amphiphilic peptides, leading to nanoparticles with a positive zeta potential in the appropriate range for biological applications.

The adsorption/desorption behaviors of cationic peptides onto (NDs) have been determined. An average of 3–4 shells of peptides may be adsorbed rapidly on NDs. About half of the molecules are adsorbed tightly with a high affinity for the NDs surface while the other half exchange rapidly, except when a photoactivatable peptide and irradiation is used. Stable suspensions of NDs@peptide in water can be obtained with amphiphilic peptides.Figure optionsDownload as PowerPoint slide