Chlorin e6 (Ce6) has been extensively researched and developed as an antitumor therapy. Ce6 is a highly effective photosensitizer and sonosensitizer with promising future applications in photodynamic therapy, dynamic acoustic therapy, and combined acoustic and light therapy for tumors. Ce6 is also being studied for other applications in fluorescence navigation, antibacterials, and plant growth regulation. Here we review the role and research status of Ce6 in tumor therapy and the problems and challenges of its clinical application. Other biomedical effects of Ce6 are also briefly discussed. Despite the difficulties in clinical application, Ce6 has significant advantages in photodynamic therapy (PDT)/sonodynamic therapy (SDT) against cancer and offers several possibilities in clinical utility.

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The introduction of different pore diameters in metal organic frameworks (MOFs) could adjust their drug delivery performance. MOFs with customized structures have potential application value in targeted drug delivery. However, no research on this topic has been found so far. In this report, isoreticular metal organic frameworks (IRMOFs) have been taken as a typical case of tailor-made MOFs, the pore size of which is enlarged (average BJH pore sizes of about 2.43, 3.06, 5.47, and 6.50 nm were determined for IRMOF-1, IRMOF-8, IRMOF-10, and IRMOF-16, respectively), emphasizing the relationship between pore size and model drugs (Oridonin, ORI) and clarifying its potential working mechanism. IRMOF-1, whose pore size matches the size of ORI, has an outstanding drug loading capacity (57.93% by wt) and release profile (about 90% in 24 h at pH 7.4). IRMOF-1 was further coated with polyethylene glycol (PEG) modified with a cell penetrating peptide (CPP44) bound to M160 (CD163L1) protein for targeting of hepatic tumor lines. This nanoplatform (CPP44-PEG@ORI@IRMOF-1) exhibited acid-responsive drug release behavior (37.86% in 10 h at pH 7.4 and 66.66% in 10 h at pH 5.5) and significantly enhanced antitumor effects. The results of cell targeting and in vivo animal imaging indicated that CPP44-PEG@ORI@IRMOF-1 may serve as a tumor-selective drug delivery nanoplatform. Toxicity assessment confirmed that PEGylated IRMOF-1 did not cause organ or systemic toxicity. Furthermore, it is encouraging that the IRMOF-based targeted drug delivery system with pore size modulation showed rapid clearance (most administered NPs are metabolized from urine and feces within 1 week) and avoided accumulation in the body, indicating their promise for biomedical applications. This MOF-based aperture modulation combined with a targeted modification strategy might find broad applications in cancer theranostics. Thus, it is convenient to customize personalized MOFs according to the size of drug molecules in future research.

Metal–organic frameworks (MOFs) are porous materials composed of metal ions and organic ligands. Due to their large surface area, easy modification, and good biocompatibility, MOFs are often used in bio-related fields. Fe-based metal–organic frameworks (Fe-MOFs), as important types of MOF, are favored by biomedical researchers for their advantages, such as low toxicity, good stability, high drug-loading capacity, and flexible structure. Fe-MOFs are diverse and widely used. Many new Fe-MOFs have appeared in recent years, with new modification methods and innovative design ideas, leading to the transformation of Fe-MOFs from single-mode therapy to multi-mode therapy. In this paper, the therapeutic principles, classification, characteristics, preparation methods, surface modification, and applications of Fe-MOFs in recent years are reviewed to understand the development trends and existing problems in Fe-MOFs, with the view to provide new ideas and directions for future research.