Integrated optical and thermal modeling for the development of a scalable multi-sample light-assisted drying platform...

Light-Assisted Drying (LAD) is a new technique for stabilizing biologics such as vaccines and protein-based therapeutics by using near-infrared laser radiation to drive selective water removal and encapsulate materials within a protective sugar matrix. This process enables room-temperature storage of biological products and reduces dependence on costly cold-chain logistics. While previous studies utilized single-sample LAD, this work introduces a multi-sample platform for the first time. By integrating optical and thermal modeling, we demonstrate that 1,064 nm radiation allows for energy reuse across vertically stacked samples to enable scalable, high-throughput processing.

LightTools optical simulations were used to model laser energy deposition across vertically stacked samples. A lumped-parameter thermal model was developed to predict temperature evolution and drying behavior during laser irradiation. Together, these models guided the design of a processing system. A prototype system was subsequently constructed and tested.

LightTools simulations revealed that each sample absorbed $<10\%$ of incident laser power, enabling a vertical stacking configuration. A lumped-parameter thermal model was developed which predicted that a 5 W near-infrared laser could process a three-sample stack within 100 min while maintaining peak temperatures below 33 °C. To validate these models, a prototype system was constructed and tested using Human Immunoglobulin G (Human IgG) as a model biologic. Experimental results demonstrated that all samples dried within 100 min without exceeding the thermal denaturation threshold. Enzyme-Linked Immunosorbent Assay (ELISA) confirmed that processed Human IgG retained full binding affinity ( $p>0.05$ compared to unprocessed controls), and Differential Scanning Calorimetry (DSC) showed no significant changes in the protein's melting temperature $(T_m\approx$ 73 °C) or unfolding enthalpy $\left(\Delta H\right)$ .

These findings demonstrate the feasibility of a high-throughput LAD system and represent an important step toward its industrial-scale implementation for biologic preservation.