No abstract

Targeting ligands are conjugated onto nanoparticles to increase their selectivity for diseased cells. However, they become covered by serum proteins which prevent them from binding to target receptors. Here, we show that the nanoparticle protein corona achieved a maximum thickness in serum because the protein adsorption and desorption rates reached an equilibrium. Simulation experiments suggest that the number of molecular interactions between proteins decrease with distance from the nanoparticle surface until the forces are too weak to hold the proteins together. This results in an equilibration state between the proteins on the nanoparticle surface and in biological fluids. Conjugating targeting ligands to this equilibrated protein corona allowed the nanoparticles to bind to target cells in the presence of serum proteins. In contrast, conjugating targeting ligands directly to the nanoparticle surface resulted in a 55% reduction in binding to target cells in serum. We demonstrated this concept using two nanoparticle material types with different surface chemistries. We present a ligand-on-corona conjugation strategy that overcomes the negative impact of serum protein adsorption on nanoparticle cellular targeting.

This thallium telluride is bestowed with an ultralow thermal conductivity in comparison to state-of-the-art thermoelectrics.

Background and Objectives: Dental professionals often recommend changing toothbrushes every three months due to their wear and decreased plaque removal efficacy. This study aimed to assess the correlation of duration of use of a toothbrush and its wear and then the relationship of wear of toothbrush and Plaque Index (PI) of users and tapering of toothbrush filaments after three months of use was evaluated as well. Materials and Methods: In this study, 60 female students were enrolled according to the eligibility criteria and received a new set of toothbrush and toothpaste. They were requested to brush their teeth using the Bass technique twice a day for 2 minutes and the Ramfjord PI was measured at baseline and after 3 months. The wear of 47 toothbrushes after three months of use was evaluated using the Rawls index. Of collected 47 toothbrushes, 30 were randomly chosen and inspected under an electron microscope to determine the degree of tapering of bristles. Data were analyzed using SPSS version 20 via Spearman’s correlation coefficient, paired t-test and Pearson’s correlation coefficient (alpha=0.05). Results: After 3 months, the mean PI score significantly decreased (paired t-test, P=0.034). The PI at 3 months after use had no significant correlation with the toothbrush wear score (Spearman’s correlation coefficient, P=0.61) but the toothbrush wear score had a significant correlation with tapering of bristles (Spearman’s correlation coefficient, P=0.04). No significant association existed between PI at 3 months after use and tapering of bristles (Pearson’s correlation coefficient, P=0.69). Conclusion: The duration of use and wear of toothbrush alone do not affect the quality of plaque removal. Practicing Oral hygiene can affect the quality of plaque removal.