tRNA conjugation with chitosan nanoparticles: An AFM imaging study

• The effect of chitosan nanoparticles on tRNA aggregation and particle formation is studied here.
• Chitosan binds tRNA via hydrophilic and electrostatic interactions.
• Chitosan-200 forms stronger tRNA complexes than chitosan-100 ad chitosan-15 kDa.
• Major tRNA aggregation and particle formation occurred on chitosan complexation.
• tRNA remains in A-family conformation in the presence of chitosan nanoparticles.

The conjugation of tRNA with chitosan nanoparticles of different sizes 15,100 and 200 kDa was investigated in aqueous solution using multiple spectroscopic methods and atomic force microscopy (AFM). Structural analysis showed that chitosan binds tRNA via G-C and A-U base pairs as well as backbone PO2 group, through electrostatic, hydrophilic and H-bonding contacts with overall binding constants of KCh-15-tRNA = 4.1 (±0.60) × 103 M−1, KCh-100-tRNA = 5.7 (±0.8) × 103 M−1 and KCh-200-tRNA = 1.2 (±0.3) × 104 M−1. As chitosan size increases more stable polymer-tRNA conjugate is formed. AFM images showed major tRNA aggregation and particle formation occurred as chitosan concentration increased. Even though chitosan induced major biopolymer structural changes, tRNA remains in A-family structure.