Antibacterial Photodynamic Therapy in the Near-Infrared Region with a Targeting Antimicrobial Peptide Connected to a π-Extended Porphyrin.

The increase of antimicrobial resistance to conventional antibiotics is worldwide a major health problem that requires the development of new bactericidal strategies. Antimicrobial photodynamic therapy (a-PDT) that generates reactive oxygen species acting on multiple cellular targets is unlikely to induce bacterial resistance. This localized treatment requires, for safe and efficient treatment of nonsuperficial infections, a targeting photosensitizer excited in the near IR. To this end, a new conjugate consisting of an antimicrobial peptide linked to a π-extended porphyrin photosensitizer was designed for a-PDT. Upon irradiation at 720 nm, the conjugate has shown at micromolar concentration strong bactericidal action on both Gram-positive and Gram-negative bacteria. Moreover, this conjugate allows one to reach a low minimum bactericidal concentration with near IR excitation without inducing toxicity to skin cells.

Lipid-polymer hybrid nanoparticle-mediated therapeutics delivery: advances and challenges.

With rapid advances in nanomedicine, lipid-polymer hybrid nanoparticles (LPHNPs) have emerged as promising nanocarriers for several biomedical applications, including therapeutics delivery and biomedical imaging. Significant research has been dedicated to biomimetic or targeting functionalization, as well as controlled and image-guided drug-release capabilities. Despite this research, the clinical translation of LPHNP-mediated therapeutics delivery has progressed incrementally. In this review, we discuss the recent advances in and challenges to the development and application of LPHNPs, present examples to demonstrate the advantages of LPHNPs in therapeutics delivery and imaging applications, and discuss the translational obstacles to LPHNP technology.

Cell death mechanistic study of photodynamic therapy against breast cancer cells utilizing liposomal delivery of 5,10,15,20-tetrakis(benzo[b]thiophene) porphyrin.

5,10,15,20-Tetrakis(benzo[b]thiophene) porphyrin (BTP) is a newly synthesized hydrophobic photosensitizer with fluorescence quantum yield in toluene: ΦF=0.062. Previously, its limitations in solubility had hindered scientific experimentation regarding its photodynamic effects on cancer cells. By utilizing various compositions of liposomes in order to alter the solubility of BTP, the photocytotoxicity, reactive oxygen species generation, and subcellular localization of the liposomal BTP were identified in this work. DNA fragmentation and high content screening assays were performed in order to shed light on the tumoricidal mechanism of the liposomal photosensitizer. The MTT assay results showed promising results in the irradiation specific PDT activity against MCF-7 cells in all liposomal compositions. Production of ROS was confirmed in the liposomal BTP treated MCF-7 cells after irradiation in a concentration dependent manner. The subcellular localization assays revealed that the localization of BTP was dependent on both the photosensitizer's chemical properties and the properties of the delivery agent encapsulating aforesaid substance. Significant DNA fragmentation was observed in both nucleus localizing liposomal BTP, BTP encapsulated DOPC and DOPE (DOPC-BTP and DOPE-BTP), treated MCF-7 cells. All liposomal-BTPs were successful in inducing mitochondrial permeability transition, an increase in the permeability of the mitochondrial membrane, and activating caspase-3/7. ER localizing BTP were able to significantly increase the cytosolic calcium levels by photodynamic therapy, confirming the photodynamic ability of ER localized BTP to damage the ER membrane. The application of liposomes in delivering a novel hydrophobic photosensitizer, BTP, and photodynamic therapy treatment against MCF-7 cells were successful. It was confirmed that the MCF-7 cell death pathway via photodynamic therapy was altered in a controlled manner by controlling the intracellular localization of the photosensitizer through lipid composition adjustment.

Bifunctional Therapeutic High-Valence Silver-Pyridoxine Nanoparticles with Proliferative and Antibacterial Wound-Healing Activities.

The antibacterial and moisturizing effects inherent to silver nanoparticles contribute greatly to their use as a topical antibacterial agent. The antibacterial property of silver nanoparticles provides topical wounds with an indirect environment for healing through the prevention of pathogenic infection. However, the direct wound-healing effects of silver nanoparticles have not been previously explored. In this work, we report a bimodal therapeutic silver nanoparticle that possesses both direct wound-healing and antibacterial properties. The nanoparticles consist of high-valence silver-pyridoxine complexes. The wound-healing efficacy was verified in diabetic mice, as well as in vitro assays. A MAPK pathway study demonstrated that silver-pyridoxine nanoparticles induced the proliferation and migration of keratinocyte and fibroblast cells. Antibacterial activities in 8 different pathogenic bacteria responsible for the infection of burn wounds were tested. The rapid wound healing occurring on skin wounds of diabetic mice attests to the utility of bimodal therapeutic silver nanoparticles as a next-generation topical therapeutic agent.

Shape-Dependent Skin Penetration of Silver Nanoparticles: Does It Really Matter?

Advancements in nano-structured materials have facilitated several applications of nanoparticles (NPs). Skin penetration of NPs is a crucial factor for designing suitable topical antibacterial agents with low systemic toxicity. Available reports focus on size-dependent skin penetration of NPs, mainly through follicular pathways. Herein, for the first time, we demonstrate a proof-of-concept study that entails variations in skin permeability and diffusion coefficients, penetration rates and depth-of-penetration of differently shaped silver NPs (AgNPs) via intercellular pathways using both in vitro and in vivo models. The antimicrobial activity of AgNPs is known. Different shapes of AgNPs may exhibit diverse antimicrobial activities and skin penetration capabilities depending upon their active metallic facets. Consideration of the shape dependency of AgNPs in antimicrobial formulations could help developing an ideal topical agent with the highest efficacy and low systemic toxicity.

Mitochondria and DNA Targeting of 5,10,15,20-Tetrakis(7-sulfonatobenzo[b]thiophene) Porphyrin-Induced Photodynamic Therapy via Intrinsic and Extrinsic Apoptotic Cell Death.

Photodynamic therapy (PDT) selectively targets subcellular organelles and promises an excellent therapeutic strategy for cancer treatment. Here, we report the synthesis of a new water-soluble photosensitizer, 5,10,15,20-tetrakis (7-sulfonatobenzo[b]thiophene) porphyrin (SBTP). Rational design of the porphyrinic molecule containing benzo[b]thiophene moiety at the meso-position led to selective accumulation in both mitochondria and nucleus of MCF-7 cells. This multitarget ability of SBTP can cause damage to mitochondria as well as DNA simultaneously. FACS analysis showed rapid cellular uptake of SBTP. High-content cell-based assay was executed to concurrently monitor increase of cytosolic Ca(2+) levels, mitochondrial permeability transition (MPT), and caspase-3/7/8 activation in MCF-7 cells under the pathological condition caused by PDT action of SBTP. The study of cell death dynamics showed that PDT action of SBTP caused an increase in the MPT followed by an increase in cytosolic Ca(2+) level. The localization of SBTP in the mitochondria activated the intrinsic apoptotic pathway. Additionally, localization of SBTP in the nucleus led to DNA damage in MCF-7 cells. The DNA fragmentation that occurred by PDT action of SBTP was thought to be responsible for extrinsic apoptosis of MCF-7 cells. SBTP demonstrated effective PDT activity of 5 µM IC50 value to MCF-7 cells by bitargeting mitochondria and DNA.

Nanosized silver (II) pyridoxine complex to cause greater inflammatory response and less cytotoxicity to RAW264.7 macrophage cells.

With advancements in nanotechnology, silver has been engineered into a nanometre size and has attracted great research interest for use in the treatment of wounds. Silver nanoparticles (AgNPs) have emerged as a potential alternative to conventional antibiotics because of their potential antimicrobial property. However, AgNPs also induce cytotoxicity, generate reactive oxygen species (ROS), and cause mitochondrial damage to human cells. Pyridoxine possesses antioxidant and cell proliferation activity. Therefore, in the present investigation, a nanosilver-pyridoxine complex (AgPyNP) was synthesized, and its cytotoxicity and immune response was compared with AgNPs in macrophage RAW264.7 cells. Results revealed that AgPyNPs showed less cytotoxicity compared with AgNPs by producing a smaller amount of ROS in RAW264.7 cells. Surprisingly, however, AgPyNPs caused macrophage RAW264.7 cells to secrete a larger amount of interleukin-8 (IL-8) and generate a more active inflammatory response compared to AgNPs. It activated TNF-α, NF-κB p65, and NF-κB p50 to generate a more vigorous immune protection that produces a greater amount of IL-8 compared to AgNPs. Overall findings indicate that AgPyNPs exhibited less cytotoxicity and evoked a greater immune response in macrophage RAW264.7 cells. Thus, it can be used as a better wound-healing agent than AgNPs. Graphical AbstractFigurative representation of the comparison of AgNPs and AgPyNPs in macrophage RAW264.7 cells in terms of cytotoxicity and immune response.

Cell lysis-free quantum dot multicolor cellular imaging-based mechanism study for TNF-α-induced insulin resistance.

BACKGROUND: TNF-α is an inflammatory cytokine that plays an important role in insulin resistance observed in obesity and chronic inflammation. Many cellular components involved in insulin signaling cascade are known to be inhibited by TNF-α. Insulin receptor substrate (IRS)-1 is one of the major targets in TNF-α-induced insulin resistance. The serine phosphorylation of IRS-1 enables the inhibition of insulin signaling. Until now, many studies have been conducted to investigate the mechanism of TNF-α-induced insulin resistance based on Western blot. Intracellular protein kinase crosstalk is commonly encountered in inflammation-associated insulin resistance. The crosstalk among the signaling molecules obscures the precise role of kinases in insulin resistance. We have developed a cell lysis-free quantum dots (QDots) multicolor cellular imaging to identify the biochemical role of multiple kinases (p38, JNK, IKKß, IRS1ser, IRS1tyr, GSK3ß, and FOXO1) in inflammation-associated insulin resistance pathway with a single assay in one run. QDot-antibody conjugates were used as nanoprobes to simultaneously monitor the activation/deactivation of the above seven intracellular kinases in HepG2 cells. The effect of the test compounds on the suppression of TNF-α-induced insulin resistance was validated through kinase monitoring. Aspirin, indomethacin, cinnamic acid, and amygdalin were tested. RESULTS: Through the measurement of the glycogen level in HepG2 cell treated with TNF-α, it was found that aspirin and indomethacin increased glycogen levels by almost two-fold compared to amygdalin and cinnamic acid. The glucose production assay proved that cinnamic acid was much more efficient in suppressing glucose production, compared with MAP kinase inhibitors and non-steroidal anti-inflammatory drugs. QDot multicolor cellular imaging demonstrated that amygdalin and cinnamic acid selectively acted via the JNK1-dependent pathway to suppress the inflammation-induced insulin resistance and improve insulin sensitivity. CONCLUSION: The regulatory function of multiple kinases could be monitored concurrently at the cellular level. The developed cellular imaging assay provides a unique platform for the understanding of inflammation and insulin resistance signaling pathways in type II diabetes mellitus and how they regulate each other. The results showed that amygdalin and cinnamic acid inhibit serine phosphorylation of IRS-1 through targeting JNK serine kinase and enhance insulin sensitivity.