Magnetic and pH dual-responsive mesoporous silica nanocomposites for effective and low-toxic photodynamic therapy

Nonspecific targeting, large doses and phototoxicity severely hamper the clinical effect of photodynamic therapy (PDT). In this work, superparamagnetic Fe₃O₄ mesoporous silica nanoparticles grafted by pH-responsive block polymer polyethylene glycol-b-poly(aspartic acid) (PEG-b-PAsp) were fabricated to load the model photosensitizer rose bengal (RB) in the aim of enhancing the efficiency of PDT. Compared to free RB, the nanocomposites (polyethylene glycol-b-polyaspartate-modified rose bengal-loaded magnetic mesoporous silica [RB−MMSNs]) could greatly enhance the cellular uptake due to their effective endocytosis by mouse melanoma B16 cell and exhibited higher induced apoptosis although with little dark toxicity. RB−MMSNs had little dark toxicity and even much could be facilitated by magnetic field in vitro. RB−MMSNs demonstrated 10 times induced apoptosis efficiency than that of free RB at the same RB concentration, both by cell counting kit-8 (CCK-8) result and apoptosis detection. Furthermore, RB−MMSNs-mediated PDT in vivo on tumor-bearing mice showed steady physical targeting of RB−MMSNs to the tumor site; tumor volumes were significantly reduced in the magnetic field with green light irradiation. More importantly, the survival time of tumor-bearing mice treated with RB−MMSNs was much prolonged. Henceforth, polyethylene glycol-b-polyaspartate-modified magnetic mesoporous silica (MMSNs) probably have great potential in clinical cancer photodynamic treatment because of their effective and low-toxic performance as photosensitizers’ vesicles.

Novel therapeutics for bacterial infections

The relentless increase in antibiotic resistance among all major groups of bacterial pathogens shows no sign of abating. The situation is exacerbated by a marked decline in the number of new antibiotics entering the marketplace. It is essential that new ways to treat severe bacterial infections are investigated before the antibiotic well runs dry. This review covers many promising approaches, some novel and some based on old ideas that were not considered viable when clinicians were able to exploit a wide palette of cheap and effective antibacterial chemotherapeutics. These approaches include the use of photosensitive dyes, bacteriophage and phage-encoded proteins, and agents that compromise virulence and antibiotic-resistance machineries. I also make a case for continuing in some form with tried and trusted platforms for drug discovery that served society well in the past.

808 nm light responsive nanotheranostic agents based on near-infrared dye functionalized manganese ferrite for magnetic-targeted and imaging-guided photodynamic/photothermal therapy

Near-infrared (NIR) light induced phototherapy has attracted considerable attention due to its deep therapeutic depth. To improve the therapeutic outcome and address non-selective side effects, the combination of complementary phototherapeutic strategies in a single nanoagent with precise targeting ability may provide an effective approach for cancer therapy. Thus we have developed an 808 nm NIR light triggered nanosystem based on IR806 dye functionalized MnFe₂O₄ (MFO-IR) for synchronous magnetic targeted and magnetic resonance (MR) imaging guided in vivo photodynamic/photothermal synergistic therapy. In this construction strategy, carboxylic acid functionalized NIR dye IR806 is explored as an 808 nm NIR-excited photosensitizer (PS) for the first time, which can also provide a conjugation site for MnFe₂O₄ nanoparticles (MFO NPs). Here, monodisperse MFO NPs have multiple capacities as dye carriers, targeting ligands, MRI contrast agents and photothermal agents. MFO-IR nanocomposites (NCs) with negligible toxicity present efficient NIR-mediated photothermal damage and ROS cytotoxicity via the relevant in vitro experimental investigations. With ideal magnetic targeting effects and remarkable NIR light-responsive properties, these MFO-IR NCs exhibit high in vivo tumor localization and could destroy subcutaneous solid tumors completely under an external magnetic field and 808 nm laser irradiation. Consequently, this magnetic nanosystem has great potential for simultaneous diagnosis and precise cancer phototherapy.

Photo-Cross-Linkable Polymer Dots with Stable Sensitizer Loading and Amplified Singlet Oxygen Generation for Photodynamic Therapy

Photodynamic therapy (PDT) is a promising treatment modality for clinical cancer therapy. However, the therapeutic effect of PDT is strongly dependent on the property of photosensitizer. Here, we developed photo-cross-linkable semiconductor polymer dots doped with photosensitizer Chlorin e6 (Ce6) to construct a nanoparticle platform for photodynamic therapy. Photoreactive oxetane groups were attached to the side chains of the semiconductor polymer. After photo-cross-linking reaction, the Ce6-doped Pdots formed an interpenetrated structure to prevent Ce6 leaching out from the Pdot matrix. Spectroscopic characterizations revealed an efficient energy transfer from the polymer to Ce6 molecules, resulting in amplified generation of singlet oxygen. We evaluated the cellular uptake, cytotoxicity, and photodynamic effect of the Pdots in gastric adenocarcinoma cells. In vitro photodynamic experiments indicated that the Ce6-doped Pdots (∼10 μg/mL) effectively killed the cancer cells under low dose of light irradiation (∼60 J/cm²). Furthermore, in vivo photodynamic experiments were carried out in tumor-bearing nude mice, which indicated that the Pdot photosensitizer apparently suppressed the growth of solid tumors. Our results demonstrate that the photo-cross-linkable Pdots doped with photosensitizer are promising for photodynamic cancer treatment.

Improving photocatalytic oxygenation mediated by polymer supported photosensitizers using semiconductor quantum dots as ‘light antennas’

Semiconductor nanoparticles (quantum dots) sensitize the photochemical generation of singlet oxygen at the surface of a photoactive polymer.

Two New Oxovanadium(IV) Compounds Containing Amino Acid Schiff Base and 1,10-Bathophenanthroline Ligands: Syntheses, Crystal Structures, and In Vitro Evaluation of the Anticancer Activities

Two new oxovanadium(iv) compounds containing 1,10-bathophenanthroline (Bphen) and amino Schiff base derivatives [VO(hnd-napha)(Bphen)] (1) and [VO(o-van-met)(Bphen)] (2) were synthesised (where hnd-napha and o-van-met are N-Schiff bases derived from the reaction of 2-hydroxy-1-naphthaldehyde with 3-(1-naphthyl)-l-alanine and o-vanillin with l-methionine, respectively). These compounds were characterised by elemental analysis, infrared spectroscopy, high-resolution mass spectrometry, and single-crystal X-ray diffraction (XRD). Both compounds showed low molar conductance values, indicating that they are non-electrolytes. The XRD results showed that the VIV atoms in both compounds existed in the VO3N3 coordination geometry with Schiff base and Bphen ligands. The in vitro anticancer activities of compounds 1 and 2 were evaluated against A549 human lung carcinoma and HepG2 human hepatoma cell lines using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and the results revealed that both compounds were cytotoxic with half maximal inhibitory concentration (IC50) values in the range of 8.22 ± 1.0 to 94.89 ± 3.2 μmol L−1. Notably, compound 2 exhibited much better anticancer activity in vitro against A549 cells (8.22 ± 1 μmol L−1) than [VO(acac)2] (24 ± 6 μmol L−1) or any of our previously reported oxovanadium(iv) compounds, making it comparable in activity to cisplatin (3.1 ± 0.5 μmol L−1). These results therefore suggest that compound 2 could be used as a promising lead for the development of anticancer agents for the treatment of lung cancer.

Optical nanoprobes for biomedical applications: shining a light on upconverting and near-infrared emitting nanoparticles for imaging, thermal sensing, and photodynamic therapy

Shining a light on spectrally converting lanthanide (Ln³⁺)-doped nanoparticles: progress, trends, and challenges in Ln³⁺-nanoprobes for near-infrared bioimaging, nanothermometry, and photodynamic therapy.

Manipulating tumor hypoxia toward enhanced photodynamic therapy (PDT)

This mini-review summarizes various methods for overcoming or utilizing hypoxia for enhanced PDT.

Enhanced cancer therapy by the marriage of metabolic alteration and mitochondrial-targeted photodynamic therapy using cyclometalated Ir(iii) complexes

A series of DCA-Ir(iii) co-drug complexes were demonstrated to act in synergy by sensitizing cancer cell for PDT to achieve cancer-specifically enhanced two-photon PDT in the hypoxic muticellular tumor spheroids.

A core–shell metal–organic-framework (MOF)-based smart nanocomposite for efficient NIR/H2O2-responsive photodynamic therapy against hypoxic tumor cells

In this work, core–shell MOF-based smart nanocomposite UCNPs/MB@ZIF-8@catalase has been constructed for bio-imaging and efficient NIR/H₂O₂-responsive photodynamic therapy against hypoxic tumor cells.

Layered double hydroxide bio-composites toward excellent systematic anticancer therapy

A supramolecular bio-composite with an excellent chemotherapy–PDT synergistic anticancer effect is fabricated and shows potential application in the field of cancer therapy.