Photodynamic properties and photoinactivation of Candida albicans mediated by brominated derivatives of triarylmethane and phenothiazinium dyes

Photodynamic therapy-a promising treatment of oral mucosal infections

The treatment of oral mucosal infections is increasingly challenging owing to antibiotic resistance. Therefore, alternative antimicrobial strategies are urgently required. Photodynamic therapy (PDT) has attracted attention for the treatment of oral mucosal infections because of its ability to effectively inactivate drug-resistant bacteria, completely heal clinical infectious lesions and usually offers only mild adverse reactions. This review briefly summarizes relevant scientific data and published papers and discusses the potential mechanism and application of PDT in the treatment of oral mucosal infections.

Co-Quenching Effect between Lanthanum Metal-Organic Frameworks Luminophore and Crystal Violet for Enhanced Electrochemiluminescence Gene Detection

Exploring new electrochemiluminescence (ECL) luminophores to construct high-efficiency sensing systems is always a hot direction for developing ECL sensors. Compared with other luminophores, metal-organic frameworks (MOFs) exhibit high mass transfer ability for accelerating the reactivity in its pore channels, which is conducive to improving the performance of ECL sensors. In this work, La³⁺ -BTC MOFs (LaMOFs) are prepared as the highly active reactor and novel ECL luminophore. On this basis, a novel co-quenching effect mechanism is proposed based on double-stranded DNA (dsDNA) triggered cooperation between LaMOFs and crystal violet (CV) molecules. Under the confined pore channels of LaMOFs, CV can play an important role as the photon-acceptor due to the matched absorption spectrum with the ECL spectrum of LaMOFs, and the electron-acceptor on account of its lowest unoccupied molecular orbital level. Based on the proposed co-quenching effect mechanism, a constructed ECL gene sensor shows good assay performance toward p53 gene in the detection range of 1 pm to 100 nm with a detection limit of 0.33 pm. The co-quenching effect integrating LaMOFs with CV is expected to be a versatile approach in the construction of ECL gene sensor, which has good prospect in expanding the application range of ECL technology.

Photosensitizers Mediated Photodynamic Inactivation against Fungi

Superficial and systemic fungal infections are essential problems for the modern health care system. One of the challenges is the growing resistance of fungi to classic antifungals and the constantly increasing cost of therapy. These factors force the scientific world to intensify the search for alternative and more effective methods of treatment. This paper presents an overview of new fungal inactivation methods using Photodynamic Antimicrobial Chemotherapy (PACT). The results of research on compounds from the groups of phenothiazines, xanthanes, porphyrins, chlorins, porphyrazines, and phthalocyanines are presented. An intensive search for a photosensitizer with excellent properties is currently underway. The formulation based on the existing ones is also developed by combining them with nanoparticles and common antifungal therapy. Numerous studies indicate that fungi do not form any specific defense mechanism against PACT, which deems it a promising therapeutic alternative.

The effects of aloe emodin-mediated antimicrobial photodynamic therapy on drug-sensitive and resistant Candida albicans

The extensive and repetitive use of antifungal drugs has led to the development of drug-resistant Candida albicans. Antimicrobial photodynamic therapy (aPDT) has received considerable attention as an emerging and promising approach to combat drug-resistant microbes. This study evaluated the photodynamic effects mediated by aloe emodin (AE), a natural compound isolated from Aloe vera and Rheum palmatum, on azole-sensitive and azole-resistant C. albicans in vitro. AE exhibited no significant dark toxicity, but in the presence of light, effectively inactivated C. albicans cells in a concentration-dependent manner. The uptake of AE by fungal cells was investigated by confocal laser scanning microscopy (CLSM), and the results showed that AE possessed stronger ability to enter into C. albicans cells following light irradiation. Transmission electron microscopy analysis suggested that AE-mediated aPDT could induce damage to the cell wall, cytoplasm, and nucleus. Damage to the surface of C. albicans was observed by scanning electron microscopy. These results suggest that AE is a potential PS for use in aPDT of drug-resistant C. albicans strains, and AE-mediated aPDT shows promise as an antifungal treatment.

Diketopyrrolopyrrole–fullerene C60 architectures as highly efficient heavy atom-free photosensitizers: synthesis, photophysical properties and photodynamic activity

New diketopyrrolopyrrole–C₆₀ architectures were synthesized as potential heavy atom-free photosensitizers in photodynamic inactivation of microorganisms.

In vitro photodynamic inactivation effects of hypocrellin B on azole-sensitive and resistant Candida albicans

BACKGROUND AND AIM

The extensive use of antifungal drugs has led to resistance from Candida albicans. The search for alternative treatment against drug-resistant C. albicans is highly desirable. Antimicrobial photodynamic therapy (aPDT) is an emerging and promising approach for treating localized and superficial C. albicans infections. The aim of this study was to investigate the photodynamic inactivation (PDI) effects of hypocrellin B (HB) on azole-sensitive and resistant C. albicans in vitro.

METHODS

The PDI efficacies of HB on standard C. albicans strain (ATCC 10231), azole-sensitive clinical isolate of C. albicans, and azole-resistant clinical isolate of C. albicans were assessed. The uptake of HB in C. albicans cells was investigated by confocal laser scanning microscopy (CLSM). The PDI effects on cellular structure and surface characteristics were investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM).

RESULTS

HB exhibited no significant dark toxicity, but inactivated the azole-sensitive and resistant C. albicans in a light-dose and PS concentration-dependent manner. CLSM images indicated that PDI treated C. albicans cells showed stronger fluorescence compared to untreated cells. TEM images suggested that significant damage to the cell wall, membrane, and cytoplasm were induced by HB-mediated PDI. SEM analysis revealed that the surface of C. albicans cells became twisted and ruptured after PDI treatment.

CONCLUSIONS

Azole-sensitive and resistant C. albicans could be effectively inactivated by HB in the presence of light, and HB-mediated aPDT shows promise as an antifungal treatment for C. albicans.

Copolymeric micelles as efficient inert nanocarrier for hypericin in the photodynamic inactivation of Candida species

Aim: To evaluate the efficacy of photodynamic inactivation (PDI) mediated by hypericin encapsulated in P-123 copolymeric micelles (P123-Hyp) alone and in combination with fluconazole (FLU) against planktonic cells and biofilm formation of Candida species Materials & methods: PDI was performed using P123-Hyp and an LED device with irradiance of 3.0 mW/cm2 . Results: Most of isolates (70%) were completely inhibited with concentrations up to 2.0 μmol/l of HYP and light fluence of 16.2 J/cm2. FLU-resistant strains had synergic effect with P123-HYP-PDI and FLU. The biofilm formation was inhibited in all species, in additional the changes in Candida morphology observed by scanning electron microscopy. Conclusion: P123-Hyp-PDI is a promising option to treat fungal infections and medical devices to prevent biofilm formation and fungal spread.

Evaluation of physicochemical properties and bacterial photoinactivation of phenothiazine photosensitizers

We report herein the physicochemical properties and antimicrobial activity of a new monobrominated derivative of Azure B and its parent compound.

Synthetic, small-molecule photoantimicrobials - a realistic approach

The search for suitable, low-molecular weight photoantimicrobials for use in infection control has strong foundations in conventional antiseptic research from the early-mid 20^th Century. Many examples of dyes exist having conventional antimicrobial activity among the azine, acridine and triphenylmethane families which have since also been found to exhibit photosensitising capabilities. The prior employment of these examples in human antisepsis provides a practical basis in terms of low host toxicity, while extant structure-activity relationships for conventional antimicrobial activity can support the development of similar relationships for photoactivated cell killing. The range of chromophores covered allows progress to be made both in topical and deeper, fluid-involved infections.

The impact of antimicrobial photodynamic therapy on peri-implant disease: What mechanisms are involved in this novel treatment?

According to the American Academy of Implant Dentistry, 3 million Americans have dental implants, and this number is growing by 500,000 each year. Proportionally, the number of biological complications is also increasing. Among them, peri-implant disease is considered the most common cause of implant loss after osseointegration. In this context, microorganisms residing on the surfaces of implants and their prosthetic components are considered to be the primary etiologic factor for peri-implantitis. Some research groups have proposed combining surgical and non-surgical therapies with systemic antibiotics. The major problem associated with the use of antibiotics to treat peri-implantitis is that microorganisms replicate very quickly. Moreover, inappropriate prescription of antibiotics is not only associated with potential resistance but also and most importantly with the development of superinfections that are difficult to eradicate. Although antimicrobial photodynamic therapy (aPDT) was discovered several years ago, aPDT has only recently emerged as a possible alternative therapy against different oral pathogens causing peri-implantitis. The mechanism of action of aPDT is based on a combination of a photosensitizer drug and light of a specific wavelength in the presence of oxygen. The reaction between light and oxygen produces toxic forms of oxygen species that can kill microbial cells. This mechanism is crucial to the efficacy of aPDT. To help us understand conflicting data, it is necessary to know all the particularities of the etiology of peri-implantitis and the aPDT compounds. We believe that this review will draw attention to new insights regarding the impact of aPDT on peri-implant disease.

Biomedical applications of nano-titania in theranostics and photodynamic therapy

Titanium dioxide (TiO₂) is one of the most abundantly used nanomaterials for human life. It is used in sunscreen, photovoltaic devices, biomedical applications and as a food additive and environmental scavenger.

Implantable photonic devices for improved medical treatments

An evolving area of biomedical research is related to the creation of implantable units that provide various possibilities for imaging, measurement, and the monitoring of a wide range of diseases and intrabody phototherapy. The units can be autonomic or built-in in some kind of clinically applicable implants. Because of specific working conditions in the live body, such implants must have a number of features requiring further development. This topic can cause wide interest among developers of optical, mechanical, and electronic solutions in biomedicine. We introduce preliminary clinical trials obtained with an implantable pill and devices that we have developed. The pill and devices are capable of applying in-body phototherapy, low-level laser therapy, blue light (450 nm) for sterilization, and controlled injection of chemicals. The pill is also capable of communicating with an external control box, including the transmission of images from inside the patient’s body. In this work, our pill was utilized for illumination of the sinus-carotid zone in dog and red light influence on arterial pressure and heart rate was demonstrated. Intrabody liver tissue laser ablation and nanoparticle-assisted laser ablation was investigated. Sterilization effect of intrabody blue light illumination was applied during a maxillofacial phlegmon treatment.