From Quantification to Translation: Advanced Bioanalytical Strategies for Evaluating Targeted Drug Delivery Systems Across Molecular, Cellular, and In Vivo Scales.

Targeted Drug Delivery Systems (TDDS) have been proposed as an innovative approach for enhancing therapeutic efficiency through selective targeting of drugs. Although there has been substantial progress in the area of targeted therapy, the application of TDDS into clinical practice has been impeded by difficulties in their bioanalysis. Existing bioanalytical methods designed for small-molecule drugs are not sufficient for proper characterization of the complex structure, dynamics, and functionality of the advanced delivery systems. This article reviews various methods of bioanalysis used in the assessment of TDDS at the molecular,cellular, tissue,and in vivo levels. Special emphasis is placed on problems such as separation of encapsulated and released drugs, the formation of the protein corona, matrix effects, biodistribution analysis, and detection of very low drug concentrations. Additionally, the review highlights important translational bottlenecks, such as non-standardization of protocols, regulatory challenges, method validation difficulties, and scaling problems.Emerging approaches like artificial intelligence-enabled bioanalysis, multi-omics, smart biosensing, personalized assessment, and digital twin technology are analyzed as possible remedies to tackle the existing challenges.Collectively, these advancements underscore the importance of integrated and standardized bioanalytical frameworks for bridging preclinical evaluation with clinical translation, thereby enabling the successful development and implementation of next-generation targeted drug delivery systems.