Chemiluminescence in Combination with Organic Photosensitizers: Beyond the Light Penetration Depth Limit of Photodynamic Therapy

Natural Phytochemical and Visible Light at Different Wavelengths Show Synergistic Antibacterial Activity against Staphylococcus aureus

As the risk of antibiotic-resistant bacteria increases, interest in non-antibiotic treatment is also increasing. Among the methods used in non-antibiotic therapy, natural antibiotics such as essential oils have disadvantages such as low efficiency. In the case of phototherapy, the light used for antibacterial activities has low penetration into the human body because of its short wavelength, making it of low medical utility. To solve this problem, this study aimed to determine conditions for enhancing the antibacterial activity of natural phytochemicals and visible light. Four natural phytochemical extracts that showed high antibacterial properties in previous studies were analyzed. Synergistic effects on antibacterial activity and cytotoxicity were determined when natural phytochemical extracts and visible light were simultaneously used. As a result, it was confirmed that the antibacterial activity increased by four times when Sanguisorba officinalis L. was irradiated with 465 nm for 10 min and 520 nm for 40 min, and Uncaria gambir Roxb. was irradiated with 465 nm for 10 min and 520 nm for 60 min compared to when Sanguisorba officinalis L. and Uncaria gambir Roxb. were used alone. The synergistic effect on antibacterial activity was independent of the absorption peak of the natural phytochemical extracts. In addition, in the case of natural phytochemical extracts with improved antibacterial activity, it was confirmed that the improvement of antibacterial activity was increased in inverse proportion to the light irradiation wavelength and in proportion to the light irradiation time. The antibacterial activity was enhanced regardless of antibiotic resistance. In the case of cytotoxicity, it was confirmed that there was no toxicity to A549 cells when treated with 465 nm, the shortest wavelength among the natural phytochemical extracts. These results show how to replace blue light, which has been underutilized due to its low transmittance and cytotoxicity. They also demonstrate the high medical potential of using natural phytochemical and visible light as a combination therapy.

Potential of photodynamic therapy in the management of infectious oral diseases

Photodynamic therapy (PDT) can take place in the presence of three elements: Light with an appropriate wavelength; a photosensitizer; and the presence of oxygen. This type of treatment is very effective overall against bacterial, viral and mycotic cells. In the last 10 years many papers have been published on PDT with different types of photosensitizers (e.g., methylene blue, toluidine blue, indocyanine green, curcumin-based photosensitizers), different wavelengths (e.g., 460 nm, 630 nm, 660 nm, 810 nm) and various parameters (e.g., power of the light, time of illumination, number of sessions). In the scientific literature all types of PDT seem very effective, even if it is difficult to find a standard protocol for each oral pathology. PDT could be an interesting way to treat some dangerous oral infections refractory to common pharmacological therapies, such as candidiasis from multidrug-resistant Candida spp.

Biofilm-mediated infections by multidrug-resistant microbes: a comprehensive exploration and forward perspectives

A biofilm is a collection of microorganisms organized in a matrix of extracellular polymeric material. Biofilms consist of microbial cells that attach to both surfaces and each other, whether they are living or non-living. These microbial biofilms can lead to hospital-acquired infections and are generally detrimental. They possess the ability to resist the human immune system and antibiotics. The National Institute of Health (NIH) states that biofilm formation is associated with 65% of all microbial illnesses and 80% of chronic illnesses. Additionally, non-device-related microbial biofilm infections include conditions like cystic fibrosis, otitis media, infective endocarditis, and chronic inflammatory disorders. This review aims to provide an overview of research on chronic infections caused by microbial biofilms, methods used for biofilm detection, recent approaches to combat biofilms, and future perspectives, including the development of innovative antimicrobial strategies such as antimicrobial peptides, bacteriophages, and agents that disrupt biofilms.

Effect of skin color on optical properties and the implications for medical optical technologies: a review

Significance

Skin color affects light penetration leading to differences in its absorption and scattering properties. COVID-19 highlighted the importance of understanding of the interaction of light with different skin types, e.g., pulse oximetry (PO) unreliably determined oxygen saturation levels in people from Black and ethnic minority backgrounds. Furthermore, with increased use of other medical wearables using light to provide disease information and photodynamic therapies to treat skin cancers, a thorough understanding of the effect skin color has on light is important for reducing healthcare disparities.

Aim

The aim of this work is to perform a thorough review on the effect of skin color on optical properties and the implication of variation on optical medical technologies.

Approach

Published in vivo optical coefficients associated with different skin colors were collated and their effects on optical penetration depth and transport mean free path (TMFP) assessed.

Results

Variation among reported values is significant. We show that absorption coefficients for dark skin are ∼ 6 % to 74% greater than for light skin in the 400 to 1000 nm spectrum. Beyond 600 nm, the TMFP for light skin is greater than for dark skin. Maximum transmission for all skin types was beyond 940 nm in this spectrum. There are significant losses of light with increasing skin depth; in this spectrum, depending upon Fitzpatrick skin type (FST), on average 14% to 18% of light is lost by a depth of 0.1 mm compared with 90% to 97% of the remaining light being lost by a depth of 1.93 mm.

Conclusions

Current published data suggest that at wavelengths beyond 940 nm light transmission is greatest for all FSTs. Data beyond 1000 nm are minimal and further study is required. It is possible that the amount of light transmitted through skin for all skin colors will converge with increasing wavelength enabling optical medical technologies to become independent of skin color.

Combining ZnPc-liposomes and chitosan on a hybrid matrix for enhanced photodynamic therapy

Photodynamic therapy is an alternative treatment for several pathologies, including cancer. This therapy uses a photosensitizer capable of producing reactive oxygen species through irradiation, promoting cellular death. A limitation of photosensitizers is their low solubility in aqueous media. Hence, developing a suitable carrier for photosensitizers for specific applications is a challenge. Cervical cancer is one of the most common cancers in women, and photodynamic therapy could be an attractive alternative therapeutic approach. In this work, we synthesized films composed of chitosan, polyvinylpyrrolidone, and liposomes containing Zn-phthalocyanine. Photophysical characterization of ZnPc incorporated into films was determined by UV-vis and fluorescence. Film properties such as swelling, mechanical properties, and water vapor permeability were performed. Finally, in vitro, photodynamic evaluation of these films was performed on HeLa cells. The results indicate that incorporating Zn-Pc-liposomes into films decreases cell viability by >95 %.

Bacterial outer membrane vesicles as drug delivery carrier for photodynamic anticancer therapy

Photodynamic Therapy (PDT) is an effective tumor treatment strategy that not only induces photocytotoxicity to kill tumor cells directly but also activates the immune system in the body to generate tumor-specific immunity, preventing cancer metastasis and recurrence. However, some limitations of PDT limit the therapeutic efficacy in deep tumors. Previous studies have used different types of nanoparticles (NPs) as drug carriers of photosensitizers (PSs) to overcome the shortcomings of PDT and improve therapeutic efficacy. Among them, bacterial outer membrane vesicles (OMVs) have natural advantages as carriers for PS delivery. In addition to the targeted delivery of PSs into tumor cells, their unique immunogenicity helps them to serve as immune adjuvants to enhance the PDT-induced immune effect, providing new ideas for photodynamic anticancer therapy. Therefore, in this review, we will introduce the biogenesis and anticancer functions of OMVs and the research on them as drug delivery carriers in PDT. Finally, we also discuss the challenges and prospects of OMVs as a versatile drug delivery carrier for photodynamic anticancer therapy.

Ferrocene/ β-cyclodextrin based supramolecular nanogels as theranostic systems

A supramolecular redox responsive nanogel (NG) with the ability to sense cancer cells and loaded with a releasing therapeutic agent was synthesized using hostguest interactions between polyethylene glycol-grafted-β-cyclodextrin and ferrocene boronic acid. Cyclic voltammetry matched with other spectroscopy and microscopy methods provided strong indications regarding host-guest interactions and formation of the NG. Moreover, the biological properties of the NG were evaluated using fluorescence silencing, confocal laser scanning microscopy, and cell toxicity assays. Nanogel with spherical core-shell architecture and 100-200 nm sized nanoparticles showed high encapsulation efficiency for doxorubicin (DOX) and luminol (LU) as therapeutic and sensing agents. High therapeutic and sensing efficiencies were manifested by complete release of DOX and dramatic quenching of LU fluorescence triggered by 0.05 mM H2O2 (as an ROS component). The NGs showed high ROS sensitivity. Taking advantage of a high loading capacity, redox sensitivity, and biocompatibility, the NGs can be used as strong theranostic systems in inflammation-associated diseases.

Host-Guest Interaction-Based Supramolecular Self-Assemblies for H2O2 Upregulation Augmented Chemiluminescence Resonance Energy Transfer-Induced Cancer Therapy

Given that light is hard to reach deep tumor tissue, how to enhance photodynamic therapy (PDT) efficacy is a big challenge. Herein, we proposed the supramolecular polymer self-assemblies (HACP) with bis[2,4,5-trichloro-6 (pentyloxycar-bonyl) phenyl] oxalate as the cargos (HACP@CPPO) to realize the chemiluminescence resonance energy transfer (CRET)-induced generation of 1O2 in situ. HACP was prepared by cinnamaldehyde-modified hyaluronic acid (HA-CA) and β-cyclodextrin-modified protoporphyrin IX (β-CD-PPIX) via host-guest interactions. The CA moiety could elevate H2O2 levels for the enhanced production of chemical energy and macrocyclic CD could enhance the stacking distance of PPIX for enhanced 1O2 yield. Thus, HACP@CPPO exhibited excellent antitumor performance without light irradiation.

The Effects and Mechanisms of PBM Therapy in Accelerating Orthodontic Tooth Movement

Malocclusion is one of the three major diseases, the incidence of which could reach 56% of the imperiled oral and systemic health in the world today. Orthodontics is still the primary method to solve the problem. However, it is clear that many orthodontic complications are associated with courses of long-term therapy. Photobiomodulation (PBM) therapy could be used as a popular way to shorten the course of orthodontic treatment by nearly 26% to 40%. In this review, the efficacy in cells and animals, mechanisms, relevant cytokines and signaling, clinical trials and applications, and the future developments of PBM therapy in orthodontics were evaluated to demonstrate its validity. Simultaneously, based on orthodontic mechanisms and present findings, the mechanisms of acceleration of orthodontic tooth movement (OTM) caused by PBM therapy were explored in relation to four aspects, including blood vessels, inflammatory response, collagen and fibers, and mineralized tissues. Also, the cooperative effects and clinical translation of PBM therapy in orthodontics have been explored in a growing numbers of studies. Up to now, PBM therapy has been gaining popularity for its non-invasive nature, easy operation, and painless procedures. However, the validity and exact mechanism of PBM therapy as an adjuvant treatment in orthodontics have not been fully elucidated. Therefore, this review summarizes the efficacy of PBM therapy on the acceleration of OTM comprehensively from various aspects and was designed to provide an evidence-based platform for the research and development of light-related orthodontic tooth movement acceleration devices.

Photodynamic Therapy: From the Basics to the Current Progress of N-Heterocyclic-Bearing Dyes as Effective Photosensitizers

Photodynamic therapy, an alternative that has gained weight and popularity compared to current conventional therapies in the treatment of cancer, is a minimally invasive therapeutic strategy that generally results from the simultaneous action of three factors: a molecule with high sensitivity to light, the photosensitizer, molecular oxygen in the triplet state, and light energy. There is much to be said about each of these three elements; however, the efficacy of the photosensitizer is the most determining factor for the success of this therapeutic modality. Porphyrins, chlorins, phthalocyanines, boron-dipyrromethenes, and cyanines are some of the N-heterocycle-bearing dyes' classes with high biological promise. In this review, a concise approach is taken to these and other families of potential photosensitizers and the molecular modifications that have recently appeared in the literature within the scope of their photodynamic application, as well as how these compounds and their formulations may eventually overcome the deficiencies of the molecules currently clinically used and revolutionize the therapies to eradicate or delay the growth of tumor cells.

Friends against the Foe: Synergistic Photothermal and Photodynamic Therapy against Bacterial Infections

Multidrug-resistant (MDR) bacteria are rapidly emerging, coupled with the failure of current antibiotic therapy; thus, new alternatives for effectively treating infections caused by MDR bacteria are required. Hyperthermia-mediated photothermal therapy (PTT) and reactive oxygen species (ROS)-mediated photodynamic therapy (PDT) have attracted extensive attention as antibacterial therapies owing to advantages such as low invasiveness, low toxicity, and low likelihood of causing bacterial resistance. However, both strategies have notable drawbacks, including the high temperature requirements of PTT and the weak ability of PDT-derived ROS to penetrate target cells. To overcome these limitations, a combination of PTT and PDT has been used against MDR bacteria. In this review, we discuss the unique benefits and limitations of PTT and PDT against MDR bacteria. The mechanisms underlying the synergistic effects of the PTT–PDT combination are also discussed. Furthermore, we introduced advancements in antibacterial methods using nano-based PTT and PDT agents to treat infections caused by MDR bacteria. Finally, we highlight the existing challenges and future perspectives of synergistic PTT–PDT combination therapy against infections caused by MDR bacteria. We believe that this review will encourage synergistic PTT- and PDT-based antibacterial research and can be referenced for future clinical applications.

Combined Experimental and Theoretical Investigation into the Photophysical Properties of Halogenated Coelenteramide Analogs

Marine Coelenterazine is one of the most well-known chemi-/bioluminescent systems, and in which reaction the chemi-/bioluminophore (Coelenteramide) is generated and chemiexcited to singlet excited states (leading to light emission). Recent studies have shown that the bromination of compounds associated with the marine Coelenterazine system can provide them with new properties, such as anticancer activity and enhanced emission. Given this, our objective is to characterize the photophysical properties of a previously reported brominated Coelenteramide analog, by employing a combined experimental and theoretical approach. To better analyze the potential halogen effect, we have also synthesized and characterized, for the first time, two new fluorinated and chlorinated Coelenteramide analogs. These compounds show similar emission spectra in aqueous solution, but with different fluorescence quantum yields, in a trend that can be correlated with the heavy-atom effect (F > Cl > Br). A blue shift in emission in other solvents is also verified with the F−Cl−Br trend. More relevantly, the fluorescence quantum yield of the brominated analog is particularly sensitive to changes in solvent, which indicates that this compound has potential use as a microenvironment fluorescence probe. Theoretical calculations indicate that the observed excited state transitions result from local excitations involving the pyrazine ring. The obtained information should be useful for the further exploration of halogenated Coelenteramides and their luminescent properties.