Cationic zinc (II) phthalocyanine nanoemulsions for photodynamic inactivation of resistant bacterial strains

Nose to brain delivery of melatonin lipidic nanocapsules as a promising post-ischemic neuroprotective therapeutic modality

Ischemic stroke accounts for about 87% of all strokes, causing long-term disability in adults, and is the second leading cause of death worldwide. In search of new therapeutic modalities, the use of neuroprotective agents loaded in nanocarriers to be delivered by noninvasive means (i.e. via intranasal route) became a popular approach. In the current study, melatonin (MEL) was loaded in lipidic nanocapsules (LNCs) prepared using the phase inversion method, and characterized in terms of size, polydispersity, zeta potential, in vitro drug release, viscosity, storage stability, and ex vivo permeation across sheep nasal mucosa. Moreover, MEL-LNCs were tested for efficacy in cerebral ischemia/reperfusion (I/R/) injury model through histopathological assessment, and analysis of oxidative stress markers, pro-inflammatory cytokines, and apoptotic markers. Results showed that LNCs exhibited particle size ranging from 18.26 to 109.8 nm, negative zeta potential, good storage stability, spherical morphology, and a burst release followed by a sustained release pattern. LNCs exhibited 10.35 folds higher permeation of MEL than the drug solution across sheep nasal mucosa. Post-ischemic intranasal administration of MEL-LNCs revealed lowering of oxidative stress manifested by a decrease in malondialdehyde levels, and elevation of glutathione and superoxide dismutase levels, lowering of the inflammatory markers tumor necrosis factor-α, NO, myeloperoxidase, and significant inhibition of Caspase-3 activity as an apoptotic marker. Western blot analysis delineated a recovery of protein expression Nrf-2 and HO-1 with downregulation in the parent inflammatory markers nuclear factor kappa B p65, inducible nitric oxide synthase, Bax, and Cytochrome C expressions, and upregulation of B-cell lymphoma-2 Bcl-2, hence promoting neuronal survival. This was supported by histological evidence, revealing significant restoration of hippocampal neurons. In light of the above, it can be concluded that MEL-LNCs could be a promising delivery system for nose to brain delivery for treatment of cerebral ischemia.

Zwitterionic meso-silica/polypeptide hybrid nanoparticles for efficient azithromycin delivery and photodynamic therapy for synergistic treatment of drug-resistant bacterial infection

The treatment of drug-resistant bacterial infections attributed to the overuse of antibiotics still remains a serious challenge globally. Herein, zwitterionic charge switchable meso-silica/polypeptide hybrid nanoparticles (MSPNs) were prepared for the synergistic chemo-photodynamic therapy in the treatment of drug-resistant bacterial infections. Subsequently, azithromycin (AZT) and methylene blue (MB) were loaded in the MSPNs to form the combined chemo-photodynamic therapeutic nanoparticles (MSPNs-AZT/MB) for the treatment of methicillin-resistant Staphylococcus aureus (MRSA). Remarkably, the as-prepared MSPNs-AZT/MB exhibited a negative surface charge of -5.2 mV at physiological pH while switching into positive surface charge of 24.7 mv in an acidic environment, leading to enhanced binding with bacterial surface. The lipase-triggered AZT release up to 77.9 % was achieved, and the loaded MB demonstrated efficient singlet oxygen (¹O₂) generation for photodynamic therapy. The in vitro experimental results displayed an excellent antibacterial effect against MRSA in both planktonic and biofilm phenotypes. Additionally, the as-prepared MSPNs-AZT/MB exhibited synergistic and enhanced antibacterial infection effect up to 94 % comparing to monotherapy in a mice model. Considering the above advantages, the as-prepared combined chemo-photodynamic therapeutic nanoparticles showed promising biocompatibility and clinical potential for the efficient therapy of drug-resistant bacteria.

Recent Advances in Antimicrobial Nano-Drug Delivery Systems

Infectious diseases are among the major health issues of the 21st century. The substantial use of antibiotics over the years has contributed to the dissemination of multidrug resistant bacteria. According to a recent report by the World Health Organization, antibacterial (ATB) drug resistance has been one of the biggest challenges, as well as the development of effective long-term ATBs. Since pathogens quickly adapt and evolve through several strategies, regular ATBs usually may result in temporary or noneffective treatments. Therefore, the demand for new therapies methods, such as nano-drug delivery systems (NDDS), has aroused huge interest due to its potentialities to improve the drug bioavailability and targeting efficiency, including liposomes, nanoemulsions, solid lipid nanoparticles, polymeric nanoparticles, metal nanoparticles, and others. Given the relevance of this subject, this review aims to summarize the progress of recent research in antibacterial therapeutic drugs supported by nanobiotechnological tools.

Pharmaceutical Nanotechnology Applied to Phthalocyanines for the Promotion of the Antimicrobial Photodynamic Therapy: A Literature Review

Phthalocyanines are photosensitizers activated by light at a specific wavelength in the presence of oxygen and act topically through the production of Reactive Oxygen Species, which simultaneously attack several biomolecular targets in the pathogen agent and, therefore, have multiple and variable action sites. This nonspecific action site delineates the conventional resistance mechanisms. Antimicrobial Photodynamic Therapy (aPDT) is safe, easy to implement and, unlike conventional agents, the activity spectrum of photoantimicrobials. This work is a systematic review of the literature based on nanocarriers containing phthalocyanines in aPDT against bacteria, fungi, viruses, and protozoa. The search was performed in two different databases (MEDLINE/PubMed and Web of Science) between 2011 and May 2021. Nanocarriers often improve the action or are equivalent to free drugs, but their use allows substituting the organic solvent in the case of hydrophobic phthalocyanines, allowing for a safer application of aPDT with the possibility of prolonged release. In the case of hydrophilic phthalocyanines, they would allow for nonspecific site delivery with a possibility of cellular internalization. A single infectious lesion can have multiple microorganisms, and PDT with phthalocyanines is an interesting treatment given its ample spectrum of action. It is possible to highlight the upconversion nanosystems, which allow for the activation of phthalocyanine in deeper tissues by using longer wavelengths, as a system that has not yet been studied, but which could provide treatment solutions. The use of nanocarriers containing phthalocyanines requires more studies in animal models and clinical studies to establish the use of aPDT in humans.

Photophysical characterization and in vitro anti-leishmanial effect of 5,10,15,20-tetrakis(4-fluorophenyl) porphyrin and the metal (Zn(II), Sn(IV), Mn(III) and V(IV)) derivatives

In this report 5 compounds were synthesized and structural and their photophysical characterization was performed (Φ_Δ and Φ_f). Furthermore, in this in vitro study, their biological activity against Leishmania panamensis was evaluated. The photophysical behavior of these compounds was measured and high Φ_Δ and low Φ_f was observed. Besides, DFT quantum calculations on the electronic structures were performed. Finally, the biological activity was determined by means of the compounds capacity to inhibit the viability of parasites using the MTT assay. The inclusion of the metal ions substantially modified the photophysical and biological properties in comparison with the free metal porphyrin (1). In fact, Zn²⁺ porphyrin derivative (2) showed a marked decrease of Φ_f and increase of Φ_Δ. In this sense, using TDDFT approaches, a luminescent process for Sn⁴⁺ derivative (3) was described, where emissive states involve the ML-LCT transition. So, this led to a decrease in the singlet oxygen production (0.82-0.67). Biological results showed that all compounds inhibit the viability of L. panamensis with high efficiency; the decrease in the viability was greater as the concentration of exposure increased. Finally, under light irradiation the IC₅₀ of L. panamensis against the Zn(II)-porphyrin (2) and V(IV)-porphyrin (5) was lower than the IC₅₀ of the Glucantime control (IC₅₀ = 2.2 and 6.95 μM Vs IC₅₀ = 12.7 μM, respectively). We showed that the use of porphyrin and metalloporphyrin-type photosensitizers with exceptional photophysical properties can be successful in photodynamic therapy (PDT) against L. panamensis, being the diamagnetic ion Zn²⁺ a candidate for the preparation of metalloporphyrins with high singlet oxygen production.

Nobiletin-loaded composite penetration enhancer vesicles restore the normal miRNA expression and the chief defence antioxidant levels in skin cancer

Skin cancer is one of the most dangerous diseases, leading to massive losses and high death rates worldwide. Topical delivery of nutraceuticals is considered a suitable approach for efficient and safe treatment of skin cancer. Nobiletin; a flavone occurring in citrus fruits has been reported to inhibit proliferation of carcinogenesis since 1990s, is a promising candidate in this regard. Nobiletin was loaded in various vesicular systems to improve its cytotoxicity against skin cancer. Vesicles were prepared using the thin film hydration method, and characterized for particle size, zeta potential, entrapment efficiency, TEM, ex-vivo skin deposition and physical stability. Nobiletin-loaded composite penetration enhancer vesicles (PEVs) and composite transfersomes exhibited particle size 126.70 ± 11.80 nm, 110.10 ± 0.90 nm, zeta potential + 6.10 ± 0.40 mV, + 9.80 ± 2.60 mV, entrapment efficiency 93.50% ± 3.60, 95.60% ± 1.50 and total skin deposition 95.30% ± 3.40, 100.00% ± 2.80, respectively. These formulations were selected for cytotoxicity study on epidermoid carcinoma cell line (A431). Nobiletin-loaded composite PEVs displayed the lowest IC50 value, thus was selected for the in vivo study, where it restored skin condition in DMBA induced skin carcinogenesis mice, as delineated by histological and immuno-histochemical analysis, biochemical assessment of skin oxidative stress biomarkers, in addition to miRNA21 and miRNA29A. The outcomes confirmed that nobiletin- loaded composite PEVs is an efficient delivery system combating skin cancer.