The development of photoactive and biocompatible nanomaterials is a current major challenge of materials science and nanotechnology, as they will contribute to promoting current and future biomedical applications. A growing strategy in this direction consists of using biologically inspired hybrid materials to maintain or even enhance the optical properties of chromophores and fluorophores in biological media. Within this area, porphyrinoids constitute the most important family of organic photosensitizers. The following extensive review will cover their incorporation into different kinds of photosensitizing biohybrid materials, as a fundamental research effort toward the management of light for biomedical use, including technologies such as photochemical internalization (PCI), photoimmunotherapy (PIT), and theranostic combinations of fluorescence imaging and photodynamic therapy (PDT) or photodynamic inactivation (PDI) of microorganisms.

The modification of surfaces with multiple ligands allows the formation of platforms for the study of multivalency in diverse processes. Herein we use this approach for the implementation of a photosensitizer (PS)-nanocarrier system that binds efficiently to siglec-10, a member of the CD33 family of siglecs (sialic acid (SA)-binding immunoglobulin-like lectins). In particular, a zinc phthalocyanine derivative bearing three SA moieties (PcSA) has been incorporated in the membrane of small unilamellar vesicles (SUVs), retaining its photophysical properties upon insertion into the SUV's membrane. The interaction of these biohybrid systems with human siglec-10-displaying supported lipid bilayers (SLBs) has shown the occurrence of weakly multivalent, superselective interactions between vesicle and SLB. The SLB therefore acts as an excellent cell membrane mimic, while the binding with PS-loaded SUVs shows the potential for targeting siglec-expressing cells with photosensitizing nanocarriers.

The use of photosensitizers (PSs) in photodynamic therapy (PDT) and photodynamic inactivation of microorganisms (PDI), as well in other biomedical techniques as medical imaging, represents a challenge for improving given properties that are desired in a biological media, such as water solubility, lack of aggregation and biocompatibility, among others. This review shows the most recent and important examples of the conjugation of photosensitizers to different biomolecules to achieve this goal. The manuscript is written in an accessible way in order to give a general vision of the recent advances stimulating at the same time the curiosity of the reader.

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In the endeavor of extending the clinical use of photodynamic therapy (PDT) for the treatment of superficial cancers and other neoplastic diseases, deeper knowledge and control of the subcellular processes that determine the response of photosensitizers (PS) are needed. Recent strategies in this direction involve the use of activatable and nanostructured PS. Here, both capacities have been tuned in two dendritic zinc(II) phthalocyanine (ZnPc) derivatives, either asymmetrically or symmetrically substituted with 3 and 12 copies of the carbohydrate sialic acid (SA), respectively. Interestingly, the amphiphilic ZnPc‐SA biohybrid (1) self‐assembles into well‐defined nanoaggregates in aqueous solution, facilitating cellular internalization and transport whereas the PS remains inactive. Within the cells, these nanostructured hybrids localize in the lysosomes, as usually happens for anionic and hydrophilic aggregated PS. Yet, in contrast to most of them (e. g., compound 2), hybrid 1 recovers the capacity for photoinduced ROS generation within the target organelles due to its amphiphilic character; this allows disruption of aggregation when the compound is inserted into the lysosomal membrane, with the concomitant highly efficient PDT response.