Enhanced Fluorescence Emission and Singlet Oxygen Generation of Photosensitizers Embedded in Injectable Hydrogels for Imaging-Guided Photodynamic Cancer Therapy

Abstract

Benefiting from their inherent localized and controlled release properties, hydrogels are ideal delivery systems for therapeutic drugs or nanoparticles. In particular, applications of hydrogels for the delivery and release of photoresponsive drugs or nanoparticles are receiving increasing attention. However, the effect of the hydrogel matrix on the fluorescence emission and singlet oxygen generation efficiency of the embedded photosensitizers (PSs) has not been clarified. Herein, meso-tetrakis(1-methylpyridinium-4-yl)porphyrin (TMPyP) as a water-soluble PS was encapsulated into an injectable hydrogel formed by glycol chitosan and dibenzaldehyde-terminated telechelic poly(ethylene glycol). Compared to free TMPyP solution, the TMPyP encapsulated in the hydrogel exhibits three distinct advantages: (1) more singlet oxygen was generated under the same laser irradiation condition; (2) much longer tumor retention was observed due to the low fluidity of the hydrogel; and (3) the fluorescence intensity of TMPyP was significantly enhanced in the hydrogel due to its decreased self-quenching effect. These excellent characteristics lead to remarkable anticancer efficacy and superior fluorescence emission property of the TMPyP-hydrogel system, promoting the development of imaging-guided photodynamic therapy.

Effects of Crosslinker Concentration in Poly(Acrylic Acid)‐KOH Gel Electrolyte on Performance of Zinc‐Air Batteries

“…Secondly, a frequency sweep between 0.01 and 10 Hz was performed at 1 % maximum strain, which is within the LVER of the polymers. In an ideal gel system, the tan( δ ) value is nearly constant over wide frequency ranges . As with the amplitude sweep, G ’ is higher than G ” for PAA‐KOH containing 0.3 to 0.9 mol % MBAA over the entire frequency range, whereas G ” is higher than G ’ when 0.1 mol % MBAA is added (Figure c).…”

“…A plot of complex viscosity as a function of frequency, , is shown in Figure d, based on the data in Figure c. The complex viscosity is almost independent of frequency for 0.1 mol % MBAA, which means that the sample is a fluid with a non‐associated structure …”

Hydrogels: soft matters in photomedicine

“…387 For example, the enhanced fluorescence intensity achieved with hydrogel formulations facilitates their use in imaging-guided PDT. 347 Additional benefits arise from specific hydrogel properties (injectable, self-healing), the ability to pattern the gels, 293 control of the sol-gel transition, 500 and from advanced drug delivery techniques. For example, recently, the permeability and oral bioavailability of non-permeable drugs such as acyclovir was significantly enhanced by encapsulating the drug into the photocross-linked hydrogel matrix of PMMA in a microdevice.…”

“…TMPyP injectable hydrogel formulations also showed enhanced fluorescence emission and in in vivo experiments improved tumor accumulation. 347 González-Delgado et al prepared TMPyPpoly(lactic-co-glycolic acid) (PLGA) nanoparticles that were incorporated into Carbopol® hydrogels. Results demonstrated that such a formulation offers a significant potential for PDT application regarding its controlled drug release, good stability (6 months at 4 °C) and skin permeability.…”

Soft Self-Healing Nanocomposites

“…Self-healing soft materials find applications in engineering and bio-medical fields. The major uses of self-healing materials so far are in surface coating (Canadell et al, 2011;Yoon et al, 2012;Yang et al, 2015a), drug delivery (Huebsch et al, 2014;Liu et al, 2016;Wang et al, 2016Wang et al, , 2017aXing et al, 2016;Xia et al, 2017;Yavvari et al, 2017;Hong et al, 2018), tissue engineering (Dankers et al, 2012;Bastings et al, 2014;Gaffey et al, 2015;Rodell et al, 2015;Loebel et al, 2017), wound healing (Gaharwar et al, 2014;Han et al, 2016;Zhao et al, 2017b;Zhu et al, 2017;Li et al, 2018c), and soft robotics (Shi et al, 2015;Darabi et al, 2017;Han et al, 2017b;Liu et al, 2018b). Herein, some applications of soft self-healing nanocomposites in biomedical fields including drug delivery tissue adhesive, as well as in industrial fields including actuators, sensors, and coatings are gathered ( Table 5).…”