Abstract
Purpose :
Understanding the dynamics of the tear film is crucial in addressing dry eye. Silicon quantum dots (Si-QDs) may offer insights into the complex dynamics of tears. This study aimed to investigate the biophysical interactions of Si-QDs with dry eye formulations.
Methods :
Rheology of mixtures of hydrophilic Si-QDs with four lubricant eye formulations; Drop A (Carboxymethylcellulose), Drop B (Perfluorohexyloctane and Omega-3 fatty acids), positively charged Drop C (Mineral oils, glycerol, tyloxapol, poloxamer 188, tris hydrochloride, tromethamine, cetalkonium chloride) and Drop D (propylene glycol, hydroxypropyl guar, mineral oil, dimyristoyl phosphatidylglycerol, polyoxyl 40 stearate, sorbitan tristearate, boric acid, sorbitol, edetate disodium, polyquaternium-1polidronium chloride) was studied using a Langmuir trough on subphase of Phosphate-buffered saline (PBS). The surface pressure with a surface area of 15–75 cm2 was measured by a pressure sensor with a Wilhelmy plate. Si-QDs (10 μL of 16 µg/mL) were applied to the surface of the lubricant drops’ solution using a microsyringe. Pressure-area profiles were used to determine the compressibility and elasticity of the mixed films.
Results :
The average surface pressure of PBS was 0.012±0.002 mN/m (Mean±SD) during compression and expansion. When added with drop A and Si-QDs, the surface pressure increased to 20.2± 3.37 mN/m and 19.78±3.29 mN/m, respectively. Mixing PBS with drop B and Si-QDs resulted in surface pressures of 31.05±4.18 mN/m and 36.12±5.02 mN/m, respectively. However, when drop C and Si-QDs were added, the surface pressure was increased to 24.56±2.56 mN/m and 32.45±3.01 mN/m respectively. Hysteresis was observed during expansion, indicating instability of tears. Drop D exhibited the highest surface pressure (48.09±4.86 mN/m) among all formulations and demonstrated a higher degree of hysteresis during expansion.
Conclusions :
Si-QDs with carboxy methylcellulose and Omega-3 fatty acids improved spreading, increased compressibility, and enhanced elasticity of the tear solution, indicating tear stability. Conversely, Si-QDs with positively charged mineral oil and hydroxypropyl guar condensed the lubricant drop solution, reducing tear stability. The rheology of Si-QDs should be tested using the Langmuir trough to optimise QDs for therapeutic eye drops.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.