From passive biomaterials to active biological systems
Biomedical materials are entering a new era. For decades, biomaterials were mainly designed as passive supports: scaffolds, carriers, coatings or structural matrices. Their role was to provide compatibility, stability and mechanical support within biological environments.
Today, this paradigm is changing. A new generation of materials is emerging, not only compatible with living systems, but biologically active by nature. Among them, microalgae represent a particularly promising class of natural active materials.
Microalgae combine several properties rarely found within a single platform: photosynthetic oxygen production, biocompatibility, structural diversity, intrinsic pigmentation, surface functionalization capacity and potential for biomedical imaging. These features make them relevant for applications ranging from tissue engineering and drug delivery to tumor therapy and wound healing.
Why microalgae are attracting biomedical interest
Microalgae are microscopic photosynthetic organisms found in marine and freshwater environments. Their biological value lies in their ability to convert light and carbon dioxide into oxygen and chemical energy. This photosynthetic activity makes them highly relevant for biomedical environments where oxygen availability is limited.
Hypoxia is a central limitation in many pathological and experimental contexts. It affects solid tumors, chronic wounds and thick engineered tissues. In these environments, oxygen deprivation can impair cell metabolism, reduce therapeutic response and limit tissue regeneration.
Microalgae offer a unique response to this challenge. Instead of delivering a finite amount of oxygen, they can produce oxygen locally under light stimulation. This active oxygen-generation capacity positions them as living biomaterials capable of modifying their microenvironment in real time.
A natural platform for imaging and therapy
The biomedical value of microalgae is also linked to their pigments. Chlorophyll and other photosynthetic molecules allow microalgae to absorb light, emit fluorescence and contribute to photoacoustic imaging. These properties make them interesting candidates for diagnostic applications.
More importantly, chlorophyll can act as a natural photosensitizer. Under specific light irradiation, it can contribute to the generation of reactive oxygen species, supporting photodynamic therapy. This creates a dual functionality: microalgae can produce oxygen through photosynthesis and help convert oxygen into therapeutic reactive species under light activation.
This combination is particularly relevant for hypoxia-associated diseases, where oxygen availability directly influences treatment efficacy.
Tissue engineering: solving the oxygen limitation in 3D systems
One of the most important applications of microalgae is tissue engineering. Three-dimensional tissues and scaffolds often suffer from insufficient oxygen diffusion. As constructs become thicker or more complex, internal regions may become hypoxic, limiting cell survival, maturation and functionality.
Photosynthetic microalgae provide a biological solution to this problem. When incorporated into scaffolds or hydrogel systems, they can generate oxygen locally and help reduce hypoxia inside engineered tissues. This has strong implications for regenerative medicine, where oxygenation is essential for tissue repair, vascularization and cell viability.
This concept also highlights a broader principle: future 3D biological systems will require not only structural support, but active microenvironmental regulation. Microalgae show how living materials can contribute directly to that regulation.
Drug delivery and biohybrid microrobotics
Microalgae are also being explored as active carriers for drug delivery. Their surfaces can adsorb or bind drugs, nanoparticles and targeting agents. Some species have intrinsic motility, while others possess specific morphologies that can be engineered into biohybrid microrobots.
Spirulina, for example, has a natural spiral morphology that can support controlled movement when combined with magnetic components. This makes it possible to design systems capable of transporting therapeutic cargos, reaching target tissues and releasing drugs under external stimulation.
In oncology, microalgae-based carriers have been investigated for the delivery of chemotherapeutic agents such as doxorubicin. These systems demonstrate how natural biological structures can be transformed into multifunctional therapeutic platforms.
Targeting tumor hypoxia
Tumor hypoxia is one of the most important barriers to effective cancer treatment. Low oxygen levels can reduce the efficacy of radiotherapy and photodynamic therapy, both of which depend on oxygen to generate cytotoxic reactive species.
Microalgae offer a highly original strategy: they can generate oxygen directly within or near the tumor microenvironment. By increasing local oxygen availability, they may help restore sensitivity to oxygen-dependent therapies.
Several biohybrid systems have been developed using microalgae combined with magnetic nanoparticles, protective coatings or cell membranes. These modifications improve targeting, stability and therapeutic performance. The objective is not only to deliver a therapy, but to reshape the local tumor microenvironment to make therapy more effective.
Wound healing and regenerative oxygenation
Oxygen is essential for wound repair. It supports cell proliferation, collagen synthesis, re-epithelialization and antibacterial immune responses. In chronic wounds, especially diabetic wounds, oxygen deficiency contributes to delayed healing and poor tissue regeneration.
Microalgae-based hydrogels, patches and even photosynthetic sutures represent innovative strategies for local oxygen delivery. These systems can maintain oxygen production at the wound site and, in some cases, combine oxygenation with antibacterial photodynamic effects.
This makes microalgae particularly relevant for next-generation wound care, where the goal is not only to cover the wound, but to actively stimulate repair.
Safety considerations and translational challenges
The article also emphasizes that microalgae have shown encouraging biocompatibility in several in vitro and in vivo studies. Commonly investigated species such as Spirulina, Chlorella and diatoms have generally demonstrated low cytotoxicity across different cellular models.
However, clinical translation still requires deeper investigation. Key questions remain regarding long-term safety, immune response, biodistribution, degradation, excretion and reproducibility. Surface engineering may help reduce systemic toxicity while preserving biological activity.
For microalgae-based biomedical materials to move toward clinical use, production systems must ensure consistency, viability and functional stability.
Why controlled culture technologies will matter
The therapeutic potential of microalgae depends directly on the ability to cultivate them under controlled and reproducible conditions. These organisms are biologically active and sensitive to their environment. Their function can be influenced by light, nutrients, gas exchange, shear stress and culture homogeneity.
This is where advanced culture technologies become essential. If microalgae are to become reliable biomedical tools, their production must be scalable, gentle and standardized. Low-shear culture environments are particularly relevant because they help preserve fragile biological structures while maintaining homogeneous suspension and efficient mass transfer.
In this context, microalgae are not only promising biomedical materials. They also represent a challenge for next-generation bioprocessing.
Conclusion
Microalgae are emerging as a new class of living biomaterials with significant potential in biomedical applications. Their ability to produce oxygen, support imaging, transport therapeutic agents and regulate hypoxic microenvironments makes them uniquely suited for tissue engineering, cancer therapy and wound healing.
Although the field remains at an early stage, the scientific direction is clear. Future biomedical systems will increasingly rely on active materials capable of interacting with and reshaping biological environments.
For these applications to become clinically and industrially relevant, the next challenge will be production. Standardized, scalable and low-stress culture platforms will be essential to preserve the biological activity of microalgae and translate their potential into practical biomedical solutions.
