Advances in photodynamic antimicrobial chemotherapy

Photodynamic therapy (PDT) and photodynamic antimicrobial chemotherapy (PACT) combine light and photosensitizers to treat cancers and microbial infections, respectively. In PACT, the excitation of a photosensitizer drug with appropriate light generates reactive oxygen species (ROS) that kill pathogens in the proximity of the drug. PACT has considerably advanced with new light sources, biocompatible photosensitizers, bioconjugate methods, and efficient ROS production. The PACT technology has evolved to compete with or replace antibiotics, reducing the burden of antibiotic resistance. This review updates recent advances in PACT, with special references to light sources, photosensitizers, and emerging applications to microbial infestations. We also discuss PACT applied to COVID-19 causing SARS-CoV-2 treatment and disinfecting food materials and water. Finally, we discuss the pathogen selectivity and efficiency of PACT.     

Recent Advances in Nanotechnology for the Treatment of Melanoma

Melanoma is one of the most aggressive forms of skin cancer, with few possibilities for therapeutic approaches, due to its multi-drug resistance and, consequently, low survival rate for patients. Conventional therapies for treatment melanoma include radiotherapy, chemotherapy, targeted therapy, and immunotherapy, which have various side effects. For this reason, in recent years, pharmaceutical and biomedical research has focused on new sito-specific alternative therapeutic strategies. In this regard, nanotechnology offers numerous benefits which could improve the life expectancy of melanoma patients with very low adverse effects. This review aims to examine the latest advances in nanotechnology as an innovative strategy for treating melanoma. In particular, the use of different types of nanoparticles, such as vesicles, polymers, metal-based, carbon nanotubes, dendrimers, solid lipid, microneedles, and their combination with immunotherapies and vaccines will be discussed.     

Preliminary study on singlet oxygen production using CeF3:Tb3+@SiO2-PpIX

Luminescent properties and singlet oxygen production using CeF₃:Tb³⁺-based nanoparticles modified with SiO₂ and protoporphyrin IX (PpIX) were studied. CeF₃:Tb³⁺ nanopowder was prepared via sol–gel route, with subsequent surface coating by SiO₂ layer and the conjugation with photosensitive PpIX molecules. Radioluminescence spectra suggest an energy transfer from Ce³⁺ to Tb³⁺ ions and from Tb³⁺ to molecules of PpIX photosensitizer. The energy transfer was confirmed by photoluminescence decay curves. Singlet oxygen production was detected using a reaction of ¹O₂ with 3’-(p-aminophenyl) fluorescein (APF) chemical probe after X-Ray excitation. Qualitative changes in time resolved photoluminescence spectra in the region of 520 nm indicate ¹O₂ generation. Studied nanocomposites may be good candidates for the application in X-ray induced photodynamic therapy.     

An Intrinsic Photothermal Liquid for Light Detection and Energy Storage

Photothermal materials (PTMs) have been intensively investigated in the fields of photothermal conversion. Superior to solid PTMs, liquid PTMs are leading the trends in satisfying the demands of high flexibility and easy recycling. Successful examples of liquid PTMs are mostly formulated by dispersing solid PTMs in solvents, but suffer from the problems of phase segregation and solvent pollution. In this work, a low-cost formulation is proposed, which involves an oxidative product of ethyl oleate by iodine. It is an intrinsic liquid PTM, preserving the fluidic nature as well as possessing considerable ability for photothermal conversion. In addition to understanding the mechanism of light absorption in the visible and even near infrared windows, two examples are presented to demonstrate the great potential of liquid PTMs in broad areas such as light sensing and energy storage.     

Shape and core‐excited resonances of thionucleobases

Thionucleobases can be used in chemoradiation therapy of cancer. Shape resonances (SRs) and core‐excited resonances (CERs) can lead to fragmentation and eventually result in strand breaks of DNA. In particular, the more energetic CERs are believed to cause double‐strand breaks that can hardly be repaired. In this work, both the SRs and CERs of exemplary 2‐thiouracil, 4‐thiouracil, 2‐thiothymine, 4‐thiothymine, and 6‐aza‐2‐thiothymine are investigated using stabilization method in conjunction with long range corrected time‐dependent density functional theory. Results indicate that the energies of (1) π*₁ and π*₂ SRs, (2) n‐π* CERs, and (3) mixed resonances of π‐π* CERs with π* SRs can be significantly stabilized due to thionation of uracil or thymine. It is noteworthy that the resonant cases of (2) and (3) can be accessed by electrons even at energies below 4 eV. Consequently, the increased decay of temporary anions can enhance strand breaks of DNA.     

Red/Near‐Infrared Emissive Metalloporphyrin‐Based Nanodots for Magnetic Resonance Imaging‐Guided Photodynamic Therapy In Vivo

Near‐infrared emissive (NIR) porphyrin‐implanted carbon nanodots (PCNDs or MPCNDs) are prepared by selectively carbonization of free base or metal complexes [M = Zn(II) or Mn(III)] of tetra‐(meso‐aminophenyl)porphyrin in the presence of citric acid. The as‐prepared nanodots exhibit spontaneously NIR emission, small size, good aqueous dispersibility, and favorable biocompatibility characteristic of both porphyrins and pristine carbon nanodots. The subcellular localization experiment of nanodots indicates a lysosome‐targeting feature. And the in vitro photodynamic therapy (PDT) results on HeLa cells indicate the nanodots alone have no adverse effect on tumor cells, but display remarkable photodynamic efficacy upon irradiation. Moreover, MnPCNDs containing paramagnetic Mn(III) ions, which possesses good biocompatibility, NIR luminescence, and magnetic resonance imaging and efficient singlet oxygen production, are further studied in magnetic resonance imaging‐guided photodynamic therapy in vivo.     

Hydrogen‐Bonded Films for Zero‐Order Release of Leuprolide

Leuprolide has been widely used in androgen deprivation therapy for the treatment of advanced prostate cancer, but its use is still limited due to its short half‐life. Herein, hydrogen‐bonded layer‐by‐layer films are fabricated from PEGylated leuprolide (PEG‐LEU) and tannic acid (TA). Because of its dynamic nature, the film disintegrates gradually in water and releases PEG‐LEU and TA. The in vitro release profile indicated perfect zero‐order kinetics, which is explained by the unique release mechanism. When implanted subcutaneously in male rats, the films maintain a constant serum drug level. For a 60‐bilayer film, the serum drug level is maintained constant for ≈24 days. No initial burst release is observed, suggesting that the in vivo release also follows zero‐order kinetics. Initially, an increase in the level of serum testosterone is induced by the released drug, followed by testosterone suppression to a constant level below the castrate level, which could be maintained as long as a constant serum drug level is maintained. Since the new drug carriers avoid an initial burst release of the drug and maintain a constant serum drug level and hence a constant serum testosterone level below the castrate level, these carriers are highly promising for androgen deprivation therapy.     

Biodegradable Black-Phosphorus-Nanosheet-Based Nanoagent for Enhanced Chemo-Photothermal Therapy

Black phosphorus nanosheet (BPNS) is a promising multifunctional material in the biomedical field with biodegradability and low side effects, however its features are always weakened severely owing to its poor stability. Here, a novel method is developed for improving the defect of BPNS based on the effective protection of poly(lactic-co-glycolic acid) (PLGA), which preserves the stable photothermal therapy (PTT) effect of BPNS and biodegradability of the material. Meanwhile, doxorubicin (DOX) is loaded on BPNS/PLGA to get BPNS/PLGA/DOX for further chemotherapy and preventing the recurrence of tumor after PTT. The presented combined therapeutic strategy exploits the strengths and improves the defects of BPNS, thus developing an efficient and safe nanoagent for cancer therapy, which affords and reveals the great potential of BPNS in nanomedicine.