FIGURE 6.

MMPs’ cleavable peptides in nanocarriers’ construction. (A) An example of a nanosystem designed for drug transport with ligands to target neoplastic cells. ACPPs with an MMP sensible peptide, are directly conjugated to NM surface to facilitate nanocarrier cell uptake. (B) Fluorescence label linked to a nanocarrier surface through an MMPs’ sensible peptide emits fluorescence when active MMPs disrupt the peptide. Drugs transported by the nanocarrier can be linked to the NP through an acidic pH-sensitive bound or peptide that is disrupted in the cell, releasing the cytotoxic drug. (C) ACCP-MMP sensible peptide and PSs for PDT can be integrated to a nanosystem. PS is conjugated into the nanoprobe through an acidic pH-sensitive link or peptide. Once the PS is released into the cell, light irradiation induces ROS production damaging the tumor cell. (D) Nanocarriers can contain PTAs for PTT attached to the NPs by MMP cleavable peptides, NPs included in the probe can behave as PTAs. PTAs can also emit fluorescence under light irradiation. (E) Nanoplatforms used for chemotherapy, and magnetic treatment can also be used for fluorescent and MR images. MMP sensitive peptides are employed to deliver the system to the neoplastic cells. DOX under light irradiation emits red fluorescence. (F) Nanocarriers can be used simultaneously for PTT, PDT, and monitoring tumor cells by PA and fluorescent images. AuNPs behave as fluorescent quenchers, PTAs, and cell monitoring by PA images. MMP sensible peptides linked to BSA drive the nanoplatform to MMPs’ overexpressing cells. Abbreviations: ACPPs, activable cell-penetrating peptides; DOX, doxorubicin; MMP, matrix metalloproteinase; NM, nanomaterial; NPs, nanoparticles; PA, photoacoustic; PDT, photodynamic therapy; PTAs, photothermal transduction agents; PSs, photosensitizers; PTT, photothermal therapy.