Biomimetic Design and Bioengineering of Artificial Blood Substitutes: Recent Advances in Nanotechnology, Microfluidics, and Smart Materials for Next-Generation Synthetic Oxygen Carriers

Background: Blood transfusion is a cornerstone of modern medicine but faces significant limitations such as donor shortages, compatibility issues, and risks of infection. Artificial blood substitutes—particularly synthetic oxygen carriers—are emerging as vital alternatives. Biomimetic engineering combined with recent advances in nanotechnology, microfluidics, and smart materials has significantly enhanced the development of next-generation substitutes that aim to replicate the function of red blood cells (RBCs) safely and efficiently. Objectives: This review aims to summarize the physiological requirements, recent material innovations, design strategies, and clinical challenges associated with synthetic oxygen carriers. Special emphasis is placed on hemoglobin-based and perfluorocarbon-based carriers, as well as smart nanomaterials and microfluidic systems that mimic native blood function. Methods: A comprehensive literature review was conducted using peer-reviewed publications from 2000 to 2024 across biomedical databases. The analysis includes comparative evaluations of synthetic carrier types, design features, toxicity profiles, clinical trial outcomes, and regulatory frameworks. Results: Key innovations include the development of nanoparticle-based hemoglobin carriers (e.g., liposomes, dendrimers), stimuli-responsive polymers for adaptive oxygen delivery, and microfluidic platforms for in vitro testing. While several hemoglobin-based oxygen carriers (HBOCs) and perfluorocarbon (PFC) products have undergone clinical trials, none have achieved widespread approval due to issues like vasoconstriction and oxidative toxicity. Regulatory challenges persist, but promising new designs show improved biocompatibility and function. Conclusions: Despite hurdles in clinical translation, the integration of biomimicry with smart material science and microsystem engineering offers a promising roadmap toward effective artificial blood. Continued interdisciplinary collaboration, AI-guided design, and patient-specific personalization may drive the emergence of scalable, safe, and responsive synthetic oxygen carriers for critical care, trauma, and surgical applications.