Subscriber access provided by READING UNIV
Article
ROS-Sensitive Polymeric Nanocarriers with Red LightActivated Size Shrinkage for Remotely Controlled Drug Release Ziyang Cao, Yinchu Ma, Chunyang Sun, Zidong Lu, Zeyu Yao, Jun-Xia Wang, dongdong li, Youyong Yuan, and Xianzhu Yang Chem. Mater., Just Accepted Manuscript • DOI: 10.1021/acs.chemmater.7b04751 • Publication Date (Web): 22 Dec 2017 Downloaded from http://pubs.acs.org on December 22, 2017
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
Chemistry of Materials is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 11 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
Chemistry of Materials
ROS-Sensitive Polymeric Nanocarriers with Red LightActivated Size Shrinkage for Remotely Controlled Drug Release Ziyang Cao,†,‡,§ Yinchu Ma,‡,§ Chunyang Sun,⊥,§ Zidong Lu,†,§ Zeyu Yao,II Junxia Wang,† Dongdong Li,† Youyong Yuan†, Xianzhu Yang†,* †
School of Medicine, Institutes for Life Sciences and National Engineering Research Center for Tissue Restoration and Reconstruction, South China University of Technology, Guangzhou, Guandong 510006, P. R. China ‡
School of Biological and Medical Engineering, Hefei University of Technology, Hefei, Anhui 230009, P. R. China
⊥
Department of Radiology and Tianjin Key Laboratory of Functional Imaging, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China
II
The Affiliated High School of South China Normal University, Guangzhou 510630, P. R. China
KEYWORDS. ROS-sensitive polymer, red light-sensitive nanocarrier, shrinkable nanocarrier, activatable drug release, cancer therapy ABSTRACT: Drug delivery systems with remotely controlled drug release capability are rather attractive options for cancer therapy. Herein, a reactive oxygen species (ROS)-sensitive polymeric nanocarrier TK-PPE@NPCe6/DOX was explored to realize remotely controlled drug release by light-activated size shrinkage. The TK-PPE@NPCe6/DOX encapsulating chlorin e6 (Ce6) and doxorubicin (DOX) was self-assembled from an innovative ROS-sensitive polymer TK-PPE with the assistance of an amphiphilic copolymer poly(ethylene glycol)-b-poly(ε-caprolactone) (PEG-b-PCL). Under the 660-nm red light irradiation, ROS generated by the encapsulated Ce6 were capable of cleaving the TK linker in situ, resulting in the rapid degradation of the TK-PPE@NPCe6/DOX core. Consequently, the size of TK-PPE@NPCe6/DOX shrank from 154±4 nm to 72±3 nm, and such size shrinkage effect further triggered rapid DOX release. As evidenced by both in vitro and in vivo experiments, such ROS-sensitive polymeric nanocarriers with light-induced size shrinkage capability offer remarkable therapeutic effects in cancer treatment. This concept provides new avenues for the development of light-activated drug delivery systems for remotely controlled drug release in vivo.
1. INTRODUCTION Nanocarriers with remotely controlled drug release capability have gained significant attention during the last decades due to their great potential to enhance therapeutic efficacy for cancer and minimize damage to normal tissues.1-4 Nanomaterials that respond to internal or external stimuli,5 such as pH,6 redox potentials,7 enzymes,8 ultrasound,9 magnetic field,10 and light,11 have been utilized to fabricate such smart nanocarriers for controlled drug release. Among the various types of stimuli, light is especially attractive because it can be remotely applied with high spatial and temporal resolutions.12 However, the majority of photochemical reactions must be activated by high-energy ultraviolet (UV) or blue light, which has limited tissue penetration and inevitable phototoxicity.13 Red or near-infrared (NIR) light, with wavelengths in the range of approximately 650-950 nm, is more suitable for biomedical applications because of its greater tissue penetration, reduced scattering, and minimal phototoxicity.14-16 However, the red and NIR light is difficult to cleave the chemical bond directly, due to their low energy. Alternatively, current red or NIR light-responsive nanocarriers mainly utilize the photothermal effect to stimulate the release of loaded drugs.17-22 In addition, very few delivery systems utilize upconversion nanoparticles to convert NIR to UV or visible light,23-26 which promotes the cleavage of
photosensitive linkages and further stimulates drug release. Collectively, the development of nanocarriers responsive to red light or NIR light for remotely controlled drug release is still considerably desirable.27, 28 Photodynamic therapy (PDT), which is based on the principle of generating ROS to induce cell apoptosis by photosensitizers under red or NIR light irradiation,29-31 has garnered great attention during the last decade.32-37 Recent reports have demonstrated that thioketal groups can be readily cleaved by ROS,38-42 which inspired us to integrate a nanoparticle combining photosensitizers and ROS-responsive nanomaterials for red or NIR lightcontrolled drug release. In light of this aim, we herein construct an innovative ROS-responsive nanocarrier to realize remotely controlled drug release by red lightactivated size shrinkage. This nanocarrier TKPPE@NPCe6/DOX comprises of four components: ROSresponsive poly(thioketal phosphoester) (TK-PPE), amphiphilic diblock copolymer PEG-b-PCL, photosensitizer Ce6, and chemotherapeutic drug DOX (Figure 1A). Upon 660-nm red light irradiation, ROS produced by the encapsulated Ce6 rapidly degrades TKPPE core in situ into oligomers or small molecules; consequently, the nanocarriers TK-PPE@NPCe6/DOX shrink from 154±4 nm into 72±3 nm, which trigger the sudden burst of encapsulated DOX. Meanwhile, the generated ROS also induce tumor cell apoptosis, which combines
ACS Paragon Plus Environment
Chemistry of Materials 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
with chemotherapy for synergistic antitumor activity (Figure 1B). Excitingly, this red light-activated shrinkable polymeric nanocarrier exhibited great therapeutic effects in both in vitro cellular experiments and in vivo animal tumor model studies.
Figure 1. Preparation and characterization of the lightactivated shrinkable nanoparticle TK-PPE@NPCe6/DOX. (A) Formation and mechanism of light-activated shrinkable nanoparticle TK-PPE@NPCe6/DOX. (B) Schematic illustration of TK-PPE@NPCe6/DOX with light-activated size shrinkage for controlled DOX release. Upon 660-nm irradiation, the generated ROS was capable of degrading the TK-PPE core in situ, resulting in the size shrinkage and triggered DOX release into cell nuclei for enhanced synergistic anticancer efficacy. (C) UV-vis-NIR absorption spectra of TK-PPE@NPCe6/DOX. (D) Size changes of TKPPE@NPCe6/DOX after incubation in PBS and in PBS containing 10% FBS. 2. RESULTS AND DISCUSSION 2.1. Preparation and Characterization of ROSSensitive Polymeric Nanocarrier with Red LightInduced Size Shrinkage Capability. To substantiate our design, we first synthesized the ROS-sensitive polymer TK-PPE using thioketal (TK) bonds as a linker between phosphoester units via condensation polymerization (Figure S1A), and successful synthesis was verified using 1H NMR spectroscopy (Figure S1B). The obtained hydrophobic TK-PPE as the inner core of nanocarrier was capable of simultaneously encapsulating Ce6 and DOX by the nanoprecipitation method, and the amphiphilic polymer PEG-b-PCL was utilized to stabilize this formulation and provide a relatively inert particle surface. The UV-vis-NIR spectrum
Page 2 of 11
of TK-PPE@NPCe6/DOX (Figure 1C) showed strong absorbance at 560 nm and 660 nm, indicating the efficient co-encapsulation of DOX and Ce6. Additionally, the loading contents of Ce6 and DOX were ca. 2.46±0.17% and 5.88±0.29%, respectively. Meantime, TKPPE@NPCe6/DOX maintained their diameters in phosphate buffer saline (PBS) or in PBS containing 10% fetal bovine serum (FBS) for over 7 days (Figure 1D), which might be due to stabilization by the PEG layer. According to our design, ROS produced by the encapsulated Ce6 rapidly degrades TK-PPE in situ into oligomers or small molecules upon 660-nm red light irradiation. To demonstrate it, Ce6 was encapsulated into the TK-PPE inner core with the assistance of PEG-b-PCL (TK-PPE@NPCe6), and then the TK-PPE@NPCe6 was irradiated by a 660-nm laser (0.3 W/cm2, 60 min) and subjected to gel permeation chromatography (GPC) analysis. As shown in Figure 2A, PEG-b-PCL and TK-PPE exhibited two elution volume peaks at 21.7 min and 24.6 min, respectively. After 660-nm laser irradiation, the peak at 24.6 min corresponded to TK-PPE almost completely disappeared, and oligomers or small molecules was observed. In contrast, the degradation did not occur in the absent of light irradiation. In addition, after irradiation at different laser power densities, this TKPPE@NPCe6 was collected and lyophilized for 1H NMR analysis. As shown in Figure S2, at a power density of 0.3 W/cm2, the peak at 1.58 ppm indicated that the CH3 in the thioketal linker of TK-PPE gradually decreased as the irradiation time increased. A similar trend was also observed at power densities of 0.15 W/cm2 (Figure S3) and 0.06 W/cm2 (Figure S4), except that the degradation rate decreased with a decrease in power density. According to these 1H NMR results, the degradation rate of TK-PPE was calculated, and it exhibited laser density and time dependencies (Figure S5). It was observed that approximately 75.3% of the thioketal linker of TK-PPE was efficiently cleaved at 0.3 W/cm2, indicating the almost complete degradation of the polymer TK-PPE, which was well consistent with the result of Figure 2A. On the contrary, ca. 57.9% and 31.4% of the thioketal linker was degraded at 0.15 W/cm2 and 0.06 W/cm2, respectively. After the degradation of TK-PPE under laser irradiation, the residual PEG-b-PCL shrank into smaller particles, which was observed through DLS. As shown in Figure 2B, the size of the nanoparticle continually shrank from 154±4 nm to 72±3 nm under 660-nm red light irradiation. Interestingly, such size shrinkage was not observed when free Ce6 and blank TK-PPE@NP were separately dispersed in aqueous solution (Figure 2C), even though more ROS were generated than that of TK-PPE@NPCe6 (Figure S6). This red light-activated size shrinkage was also confirmed using transmission electron microscopy (TEM) imaging (Figure 2D), in which small particles less than 75 nm were observed after 660-nm laser irradiation. These results demonstrated that only ROS generated within the nanoparticle core can efficiently cleave the thioketal linker of TK-PPE in situ due to the short action distance (
