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Recent Trends on Smart Bioresponsive Polymeric Materials
Published in Moayad N. Khalaf, Michael Olegovich Smirnov, Porteen Kannan, A. K. Haghi, Environmental Technology and Engineering Techniques, 2020
Kalpana N. Handore, Sumit B Sharma, Santosh Mishra, Vasant V. Chabukswar
Polymers which are sensitive to temperature changes are the most studied as they have potential applications in the biomedical field. Temperature has attracted a great deal of attention because this stimulus can be easily applied and monitored. Temperature-responsive polymers change their properties due to a variation in the environmental temperature. Temperature-responsive polymers undergo an abrupt decrease in physicochemical properties above a certain temperature which is named as the lower critical solution temperature (LCST).28 Polymer chains behave hydrophilic and remain swollen (in water) below LCST, while above this temperature, the polymer chains become increasingly hydrophobic and collapse. On the other hand, polymers that are hydrophobic below a critical temperature and hydrophilic above it present an upper critical solution temperature (UCST).29
Stimuli-Responsive Polymers with Tunable Release Kinetics
Published in Onur Parlak, Switchable Bioelectronics, 2020
Mehmet Can Zeybek, Egemen Acar, Gozde Ozaydin-Ince
Temperature-responsive polymers are widely used in drug delivery applications, providing the benefit of triggering the drug release by controlling either the internal or the external stimuli. Some observations have revealed that a high metabolic activity rate, leukocyte infiltration, a high proliferation cell rate, and extraordinary blood flow directly lead to high body temperature in inflammatory types of diseases and tumors.2,35,95 For the cases when the polymer stimulation should be controlled externally, conventional clinical methods, such as radiofrequency, ultrasound, and focused microwaves, can be applied for heat localization to create mild hyperthermia.37,39,59
Plasmonic Nanoparticles for Cancer Bioimaging, Diagnostics and Therapy
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
Bridget Crawford, Tuan Vo-Dinh
The photothermal effect has been widely used to disrupt non-covalent interactions between nanoparticles and drug, resulting in the release of encapsulated drugs [163,164]. For example, drug release can be triggered by the photothermal effect by affecting the hydrophilic-hydrophobic balance of thermally responsive polymers conjugated to nanoparticles. Temperature-responsive polymers and hydrogels exhibit a volume phase transition at their lower critical solution temperature (LCST), below which the polymers are miscible in aqueous solutions, but above which they are insoluble [165]. When thermo-responsive polymers are incorporated into nanoparticle systems, a temperature increase above LCST renders the polymers hydrophobic, causing the polymers to collapse and subsequently release their drug cargo. For example, Yavuz et al. developed gold nanocages covalently functionalized with a thermo-responsive polymer, poly(N-isopropylacrylamideco-acrylicamide) (pNIPAAm-co-pAAm), with an LCST of 37°C [166]. At body temperature (37°C), the polymers were in a conformation that sealed the nanocage pores, preventing dye release. At temperatures above the LCST, the polymers collapsed, allowing the release of the dyes. When nanocages loaded with the doxorubicin (DOX), a chemotherapeutic drug, were incubated with breast cancer cells, irradiation at NIR wavelengths (730–820 nm, 20 mW/cm2, 2 min) resulted in >30% loss in cell viability. Similarly, Li et al. demonstrated that using doxorubicin-loaded HGNS for combined PTT and chemotherapy was more effective than either treatment alone in vivo and also reduced the systemic toxicity of doxorubicin [167]. Because doxorubicin has been shown to cause immunogenic cell death in cancer cells, the inflammatory response, antigen release and immunogenic apoptosis caused by combination PTT and chemotherapy could cause a potent immune response against metastatic cancer sites [168].
Multi-stimuli-responsive, liposome-crosslinked poly(ethylene glycol) hydrogels for drug delivery
Published in Journal of Biomaterials Science, Polymer Edition, 2020
Luisa L. Palmese, Ming Fan, Rebecca A. Scott, Huaping Tan, Kristi L. Kiick
Stimuli-responsive biomaterials have been the subject of fundamental research and technology development for several decades due their programmability to a myriad of cues. In particular, hydrogels have been widely studied as multifunctional materials for applications including tissue engineering, diagnostics, biosensors, microelectromechanical systems, and drug delivery [1,2]. Spatially and temporally resolved delivery of therapeutics to treat disease has remained of enormous interest, with hydrogels developed for a wide range of applications including on-demand release of insulin to manage diabetes [3], controlled release of drugs via implants for posterior eye conditions [4], and chemotherapeutics for targeted cancer treatment [5]. A particular advantage of hydrogels is the ability to incorporate multiple functional handles to selectively and locally release numerous cargos, including bioactive proteins and small molecules, based on the localization of the hydrogel in the cellular environment and its subsequent response to stimuli. Temperature-responsive polymers such as chitosan and poly(N-isopropylacrylamide) (PNIPAm) have been mainstays in stimuli responsive hydrogels for drug release. These polymers rely primarily on lower critical solution temperature behavior to induce gelation following injection and provide a platform for the release of loaded therapeutics in a sustained manner. Chitosan and PNIPAm hydrogels have been heavily studied for cancer treatment; however, there has been growing interest in including more stimuli-responsive features in biomaterials to enable sensitivity to the combination of temperature and other stimuli such as pH, ultrasound, and near infrared light [6].