Frozen Translational and Rotational Motion of Human Immunodeficiency Virus Transacting Activator of Transcription Peptide-Modified Nanocargo on Neutral Lipid Bilayer

Abstract

With time-resolved high-precision single-particle tracking methodologies, we explored the adsorption and thermal motion of transacting activator of transcription (TAT) peptide-modified nanocargo on a model lipid bilayer in the nonelectrostatic domain. We found that the lateral and rotational motion of TAT peptide-modified nanocargo could be effectively suppressed on the surface of neutral lipid membrane, a feature that cannot be explained by existing hypotheses. A semiquantitative association activation energy analysis revealed that multiple weak bonds were required for the initial adsorption process. As a result, the localized multiple TAT peptides on the surface of the nanocargo can provide a pathway for the creation of a net of peptide-lipid complexes (e.g., lipid domain). The dragging forces caused by these complexes effectively confined the thermal motion of the nanocargo on the fluid membrane that cannot be achieved by individual peptides with random spatial and conformational distributions. These interesting findings could provide insightful information for the better understanding of the intracellular internalization mechanism of TAT peptide-modified nanocargo and might shed new light on the development of highly efficient intracellular carriers for site-specific delivery of drugs and genes.

Single Particle Dynamic Imaging and Fe3+ Sensing with Bright Carbon Dots Derived from Bovine Serum Albumin Proteins

“…As indicated in Fig. 7a , when the Cdots is locating at the focal plane of the objective, the TAT-Cdots still exhibited signal to noise as high as 16, which is good enough for high precision single particle tracking on living cell membrane 56 57 58 59 .…”

“…Previous experimental results have demonstrated that the thermal energy induced Brownian diffusion of TAT-modified nanoparticles on lipid bilayer can be greatly inhibited owing to the multi-interaction points such as hydrogen bonds 59 . On living cell membrane, the translational diffusion of TAT-modified nanocargo exhibited confined behavior even in the presence of many neutral sugar molecules on the cell surface 56 .…”

“…Conjugation of TAT peptides with Cdots is based on EDC/NHS crosslinking reaction 56 59 . Briefly, 0.25 mL of purified Cdots solution was mixed with 5 μL of 1 mg/mL EDC and 12 μL of 1 mg/mL NHS for 30 min.…”

Single Particle Tracking of Peptides-Modified Nanocargo on Lipid Membrane Revealing Bulk-Mediated Diffusion

“…10 For PEG-modified particles, the MSD increases linearly with lag time τ as expected for Fickian diffusion despite the reduced diffusion coefficient in contrast to that in bulk solution, Figure 2a. 23 When TAT was introduced to the surface of GNPs, the movability decreased gradually as revealed in the slope of the curve. Distinct from the case of PEG-modified GNPs, the slope of the curve slightly declined as the lag time increased, reminiscent of a power law relation ⟨Δr(τ) 2 ⟩ = 4Dτ α (with α = 1.1, 0.73, 0.64, and 0.48 for PEG-GNPs, TAT-GNPs-1, -2, and -3, respectively).…”

“…Multiassociation forces at the contact point account for the significantly reduced translational diffusion as revealed according to the binding energy estimation. 23 To gain deep insight into the details of the diffusion process after the mixed modification, we further explored the ensemble-averaged stepsize distribution which is quantified in terms of the self-part of t h e v a n H o v e c o r r e l a t i o n f u n c t i o n ,…”