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Nanomaterials and Its Application as Biomedical Materials
Published in Savaş Kaya, Sasikumar Yesudass, Srinivasan Arthanari, Sivakumar Bose, Goncagül Serdaroğlu, Materials Development and Processing for Biomedical Applications, 2022
G.S. Mary Fabiola, P. Dhivya, M. Anto Simon Joseph
Photodynamic therapy is emerging to be a remedial modality for early detection and localized cancers. The three key components in photodynamic therapy include: photosensitizer, light, and molecular oxygen. The photosensitizer is administered either by intravenous injection or by local application depending on the part of the body to be treated. Once the drug is absorbed by the pathologic tissue, light is exposed. The photosensitizer gets activated by light and forms Reactive Oxygen Species (ROS), which in turn kill cancer directly. A major issue faced by prolonged photodynamic therapy is the increased selective accumulation of the photosensitizers within the tumor thereby leading to a lower effective dose of the drug. To improve the efficacy of photodynamic therapy, efforts were laid to bind the photosensitizer itself by ligands such as monoclonal antibodies or low-density lipoprotein (LDL) or via carrier system such as liposomes and micelles (Gibot et al. 2020).
Barriers in the Tumor Microenvironment to Nanoparticle Activity
Published in Dan Peer, Handbook of Harnessing Biomaterials in Nanomedicine, 2021
Hanan Abumanhal-Masarweh, Lilach Koren, Omer Adir, Maya Kaduri, Maria Poley, Gal Chen, Aviram Avital, Noga Sharf Pauker, Yelena Mumblat, Jeny Shklover, Janna Shainsky-Roitman, Avi Schroeder
Photodynamic therapy is based on photo-damage obtained by photosensitizers that produce reactive oxygen species under light irradiation [231]. Upon light exposure, reactive oxygen species (ROS) are generated in an environmental oxygen-consuming process [231, 232]. Therefore, tumor hypoxia limits the treatment efficacy achieved by photodynamic therapy. Nanoparticles based on complementary molecules for photodynamic therapy have been reported [232–234]. Owning a good catalytic property to decompose H2O2 into O2 and H2O in the acidic environment, MnO2 has been used in various nano-systems that aimed to re-oxygenate hypoxic regions in solid tumors thus enhancing photodynamic therapy [224, 232, 235].
Reduced Porphyrins as Photosensitizers: Synthesis and Biological Effects
Published in Barbara W. Henderson, Thomas J. Dougherty, Photodynamic Therapy, 2020
The development of new photosensitizers for photodynamic therapy remains a rapidly expanding area. However, despite the wealth of knowledge available on in vitro and in vivo effects of such sensitizers, little comparative data exist. The use of so many different protocols for sensitizer evaluation has provided insight on some occasions and confusion on others. As an example, one could discuss the delivery systems used in sensitizer evaluation. These range from simple saline solutions, to dimethyl sulfoxide (DMSO), to liposomes and emulsions. Is it correct to claim that a sensitizer given in DMSO is not active? Are all compositions filtered to remove particulate material? Perhaps the nature of the delivery carrier, so long ignored in photodynamic therapy, should be considered with more respect. Similarly, one could discuss the relevance of intraperitoneal, to intravenous, to oral administration, or the different reported methods of assessing tumor response (depth of necrosis, tumor dry weight, flat and necrotic regions, no palpable tumor, and so on) or even the tumor model itself. Each parameter dictates how a particular sensitizer is described, and until some uniformity is introduced into these areas, much of the potential to develop structure-activity relationships in photodynamic therapy will be wasted.
Platelet-biomimetic nanoparticles for in vivo targeted photodynamic therapy of breast cancer
Published in Journal of Biomaterials Science, Polymer Edition, 2022
Yangyang Song, Xue Tan, Yanan Gao
Photodynamic therapy (PDT) has received more and more attention in cancer therapy due to its unique advantages, such as safe, minimal invasion, tolerance of repeated doses, and tissue selective treatment for cancer therapy [1,2]. Effective photodynamic therapy requires the effective accumulation of photosensitizers (PSs) at the tumor site and the generation of sufficient cytotoxic reactive oxygen species (ROS) under light. From this point of view, the highly efficient delivery of PSs to the tumor site is essential for effective PDT [3,4]. However, due to some unfavorable characteristics of PSs, such as their hydrophobicity and easy to aggregate in aqueous solution, which will make them difficult to accumulate at the tumor sites. Therefore, it is very meaningful and urgent to overcome the existing shortcomings of PSs and realize their effective delivery in tumor sites.
Laccase immobilization with metal-organic frameworks: Current status, remaining challenges and future perspectives
Published in Critical Reviews in Environmental Science and Technology, 2022
Wenguang Huang, Wentao Zhang, Yonghai Gan, Jianghua Yang, Shujuan Zhang
The key of photo-activation is to establish a ternary system that includes stable light absorption, photoelectron transfer, and catalytic center excitation. As the light absorbing unit, the photosensitizer is firstly photo-activated into an excited state (generally a triplet excited state with a longer lifetime). After that, the excited photosensitizer is reduced by direct electron transfer to the surface of the laccase T1Cu (II). Oxygen absorbed by laccase acts as the final electron acceptor. In fact, the active cationic radicals or cavities produced by the photosensitizer complete the oxidation of some reducing substrates, such as EDTA, ABTS, and styrene. The early literatures are dedicated to verifying the feasibility of photoexcited electrons transfer between photosensitizer and laccase (Jalila Simaan et al., 2011; Skorupska et al., 2012). The detailed information is illustrated in Figure 4.
Tumor-targeting and imaging micelles for pH-triggered anticancer drug release and combined photodynamic therapy
Published in Journal of Biomaterials Science, Polymer Edition, 2020
Qianqian Qi, Xianwu Zeng, Licong Peng, Hailiang Zhang, Miao Zhou, Jingping Fu, Jianchao Yuan
Based on the establishment of nano drug delivery system, chemotherapy and photodynamic therapy (PDT) are often used in combination to treat cancer [12–14]. Photodynamic therapy (PDT), in recent years, has attracted a lot of attention for cancer therapy when light was switched on in the presence of photosensitizer and oxygen, generating reactive oxygen species (ROS) [15]. Compared to traditional chemotherapy and radiation therapy, PDT cancer treatment under light conditions shows a significant reduction in side effects and improved selectivity, while other tissues in the dark are unaffected [16,17]. which is therefore called a non-invasive medical technology to treat cancer. It is a technology that uses light of appropriate wavelength to activate photosensitizer (PS) molecules at the target site, which then convert surrounding O2 into reactive oxygen species (ROS), such as singlet oxygen, hydroxyl radical, etc., leading to significant accumulation of ROS, thereby enhancing intracellular oxidative stress and killing cancer cells.[18,19]Photodynamic therapy (PDT) is based on this principle, in which delivery system with encapsulated photosensitizers was injected into tissues and then irradiated at a certain wavelength to reach an excited energy level [20]. For example, Philip S. Low’s group prepared derivatives such as triphenylphosphine, sulfonium salt and biguanide. By using PSs, the intracellular redox homeostasis was imbalanced,which significantly increasing the level of reactive oxygen species (ROS) in cell mitochondria, and inducing cell apoptosis.[21] The biggest weakness of photodynamic therapy is the poor penetration ability of light, which affects the therapeutic effect.[21] However, when photodynamic therapy is used for skin cancer such as melanoma, the effect of light penetration is not significant.