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Selenium−Platinum Coordination Dendrimers with Controlled AntiCancer Activity Tianyu Li,† Mario Smet,‡ Wim Dehaen,‡ and Huaping Xu*,† †
Key Lab of Organic Optoelectronics & Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084, People’s Republic of China ‡ Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Heverlee (Leuven), Belgium S Supporting Information *
ABSTRACT: Dendrimers are considered as good vectors for drug delivery in cancer treatment. However, most anticancer drugs are conjugated to the peripheral surface of dendrimers, sacrificing the advantages of monodispersity and stability belonging to dendrimers. Furthermore, dendrimers in current studies of cancer treatment are mostly used as vectors for drugs, whereas the anticancer activity of dendrimers on their own is less studied. Here we have prepared monodisperse selenium−platinum coordination dendrimers with a selenium−platinum core buried inside. Structures of the dendrimers were determined by various characterizations. The coordination dendrimers showed controlled anticancer activity by themselves, without loading additional drugs. The in vivo study further demonstrated their anticancer activity and low toxicity to normal tissues. KEYWORDS: dendrimer, selenium, platinum, anticancer, coordination
1. INTRODUCTION Dendrimers are monodisperse macromolecules with highly branched three-dimensional structures.1,2 During the past decade, dendrimers have been considered as promising vehicles for drug delivery because of their high degree of branching, precise molecular weight, tunable surface property, and low intrinsic viscosity which can promote transport in blood.3−7 By covalently linking to or encapsulating in dendrimers, anticancer drugs can get better stability and solubility in the circulation system, as well as lower toxicity to normal cells.8,9 However, in most previous studies, drug molecules were anchored on the peripheral surface of dendrimers. This strategy generally benefits from an easy synthetic process and high drug loading, but may sacrifice stability and the monodisperse character−a unique feature of dendrimers.10−12 In addition, most dendrimers act only as vectors for releasing anticancer drugs, without activities on their own, which limits the diversity in the design of anticancer dendrimer systems.13−15 Selenium is one of the essential elements in the human body with a function of regulating the redox balance.16−19 In low concentration, selenium has the ability to eliminate reactive oxygen species (ROS), thus promoting cell growth; while in high concentration, selenium can induce production of ROS, resulting in cell apoptosis.20 This function like a “double-edged sword” has attracted much interest to this area. The antioxidant property of selenium, found in glutathione peroxidase, has been well-studied in the past 30 years. Glutathione peroxidase mimics were prepared by making use of hyperbranched polymers and dendrimers with a selenide or diselenide core.21−27 Research based on the redox properties of selenium is a rising area with lots of questions remaining. In recent years, © XXXX American Chemical Society
some people have started to focus on the mechanism of selenium-induced ROS production and cell apoptosis. The anticancer activity of selenium-containing molecules has been demonstrated.28−33 However, drug delivery systems involving selenium-containing polymers are still rarely reported. In a previous study, we constructed selenium-containing polyurethane systems, and demonstrated the anticancer ability of a selenium−platinum coordination complex.34−38 However, the polydisperse character of polymer systems limits their potential in cancer treatment. Because the chemical structures of polymers are not clear and their toxicities in the human body are difficult to be evaluated. In this work, we prepared selenium−platinum polylysine dendrimers with anticancer activity by coordinating platinum to selenium-containing dendrimers. A selenium−platinum moiety was buried in the core of the dendrimer with good stability and monodispersity. The selenium-containing dendrimer itself had the ability to regulate the concentration of ROS, which could be enhanced after the coordination between selenium and platinum according to our previous research.39,40 The anticancer activity of the dendrimers can be further controlled with different generations. Special Issue: Applied Materials and Interfaces in China Received: August 24, 2015 Accepted: September 14, 2015
A
DOI: 10.1021/acsami.5b07877 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX
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(m, 16H). MALDI-TOF: m/z 1203.70 [M + H]+. 1H NMR of DLG2Se/Pt (D2O, ppm): δ = 7.62 (d, 4H), 7.54 (d, 4H), 4.40 (m, 2H), 4.20 (m, 2H), 4.13 (m, 2H), 3.89 (m, 2H), 3.81 (m, 2H), 3.10− 3.50 (m, 8H), 2.92 (m, 12H), 1.78 (m, 8H), 1.60 (m, 12H), 1.33 (m, 16H). MALDI-TOF: m/z 1395.64 [M + H]+. 1H NMR of DLG3Se (D2O, ppm): δ = 7.58 (d, 4H), 7.31 (d, 4H), 4.10 (m, 6H), 3.91 (m, 4H), 3.82 (m, 4H), 3.77 (s, 4H), 3.43 (m, 4H), 3.38 (m, 4H), 3.09 (m, 12H), 2.89 (m, 16H), 1.78 (m, 14H), 1.60 (m, 28H), 1.34 (m, 42H). MALDI-TOF: m/z 2229.46 [M + H]+. 1H NMR of DLG3Se/Pt (D2O, ppm): δ = 7.61 (d, 4H), 7.54 (d, 4H), 4.40 (m, 2H), 4.20 (m, 2H), 4.10 (m, 6H), 3.88 (m, 4H), 3.79 (m, 4H), 3.43 (m, 4H), 3.31 (m, 4H), 3.11 (m, 12H), 2.92 (m, 16H), 1.78 (m, 14H), 1.60 (m, 28H), 1.33 (m, 42H). MALDI-TOF: m/z 2422.44 [M + H]+. Structure Characterizations of Selenium−Platinum Coordination Dendrimers. Molecular weights of the dendrimers were determined at 298 K in H2O by ABI 4800 Plus MALDI-TOF-TOF. 1 H NMR measurements were performed at 298 K in D2O (99.9% D) on a Bruker Ascend 400 MHz NMR spectrometer. Valence changes of selenium and platinum were observed with a Thermo Fisher ESCALAB 250Xi XPS spectrometer. A 1 mM sample solution of water was dropped on a silica wafer. The water was then evaporated in vacuum to get a liquid film for characterization. Cell Culture. The human hepatoma cell line HepG2 was provided by the Cell Resource Center, Shanghai Institutes for Biological Sciences (SIBS, China). The cells were cultured in DMEM/high glucose culture medium (Gibco, USA) containing 10% fetal bovine serum (Gibco, USA), 100 U/mL penicillin and 100 μg/mL streptomycin, at 37 °C in 5% CO2 humidified environment. Cellular Uptake Experiment. 1 ×105 HepG2 cells were plated in a 24-well plate for 2 days, and then incubated with 50 μM cisplatin, DLG1Se, DLG1Se/Pt, DLG2Se/Pt, and DLG3Se/Pt for 3 h at 37 °C. After incubation, the cells were washed with H2O three times, trypsinized, and lysed with lysis buffer (1 mL per well) for 20 min. Lysed cells in each well were diluted to 4 mL with H2O and processed for ICP-MS analysis to determine the intracellular concentration of selenium and platinum. In Vitro Cytotoxicity Assessment. The anticancer activities of cisplatin, DLG1Se, DLG1Se/Pt, DLG2Se/Pt, and DLG3Se/Pt were determined by MTT assay. One ×104 HepG2 cells were placed in a 96-well plate for 24 h, then treated with cisplatin, DLG1Se, DLG1Se/ Pt, DLG2Se/Pt, and DLG3Se/Pt for 24 h at 37 °C. After treatment, drug solutions in each well were replaced by fresh DMEM/high glucose medium. Ten μL of CCK-8 solution was added. The cells were incubated for 1 h at 37 °C. Absorbance at 450 nm was detected by microplate reader (PerkinElmer EnVision). HepG2 cells cultured in DMEM/high glucose medium were used as control. Five wells in a plate were used for each experimental condition. Animals and Ethics Statement. Six-month-old female BALB/C mice were purchased from Department of Laboratory Animal Science in Peking University Health Science Center (PUHSC). The mice were kept in a ventilated, temperature-controlled, and standardized sterile animal room at PUHSC. Before the experiment, the mice were acclimatized to the animal room for 5 days. All procedures were performed under the guidance of technicians in PUHSC, following the animal welfare protocols, which were approved by PUHSC Animal Care and Use Committee. In Vivo Anticancer Assessment. One ×106 4T1 breast cancer cells were inoculated subcutaneously on the right flank of mice. After the tumor grew for 10 days, the mice were divided into six groups with six mice in each group. PBS, cisplatin, DLG3Se, DLG1Se/Pt, DLG2Se/Pt, and DLG3Se/Pt (50 μL, 3 mM) were administered subcutaneously every 3 days. The concentration of platinum injected was 1.5 mg/kg, and the concentration of selenium was 0.6 mg/kg. The mice treated with an equal volume of PBS were used as control.
2. EXPERIMENTAL SECTION Materials. All chemical reagents were used without further purification. Reagents used in synthesis of selenium-containing dendrimers were purchased from Acros Organics Co. Cisplatin was purchased from Sigma-Aldrich Co. Synthesis of 4,4′-(Selenobis(methylene))dibenzoic acid. Sodium borohydride (0.36 g, 9.3 mmol) was dissolved in 10 mL water. Afterward, selenium powder (0.37 g, 4.7 mmol) was introduced into the solution, the mixture was stirred at 50 °C in oil bath until it turned transparent. 4-(Bromomethyl)benzoic acid (2 g, 9.3 mmol) and sodium hydride (0.4 g, 10 mmol) was dissolved in 40 mL water, then added into the prepared transparent solution. After stirred at 50 °C for 1 h, hydrochloric acid was added until pH 1, and the solution was stirred at 70 °C for 10 min. Then, the solution was filtered to get the solid. In order to get rid of selenium powder in excess, potassium carbonate solution was added until pH >10. The solution was stirred at 70 °C for 30 min, and filtered to get the liquid phase. The solution was again acidified by hydrochloric acid and filtered to get the solid. Finally, the solid was dried in vacuum overnight. 1H NMR (DMSO-d6, ppm): δ = 12.77 (s, 4H), 7.85 (d, 4H), 7.37 (d, 4H), 3.85 (s, 4H). 13C NMR (DMSO-d6, ppm): δ = 167.58, 145.30, 129.95, 129.46, 129.40, 27.23. Synthesis of Selenium-Containing Dendrimers (LG1Se, LG2Se, LG3Se). L-lysine monodendrons up to the third generation with N-Boc protected and amino surface groups and N-(2aminoethyl)amide group at the focal side (LG1-NH2, LG2-NH2, LG3-NH2) were synthesized according to the method reported by Appelhans et al.41 LG1-NH2 (0.42 g, 1.08 mmol) and 4,4′(selenobis(methylene))dibenzoic acid (0.18 g, 0.51 mmol) were dissolved in 100 mL of dichloromethane. N,N-Diisopropylethylamine (2 mL) was then introduced under argon protected. After all the solid was dissolved, (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluophosphate (0.48 g, 1.08 mmol) was added. The solution was stirred under argon atmosphere for 48 h. After the reaction was finished, 50 mL dichloromethane was added. The solution was then washed with 80 mL 1 M hydrochloric acid and 80 mL saturated sodium bicarbonate. After drying with sodium sulfate, the sample was purified with column chromatography (CH2Cl2: CH3OH = 8:1) to get LG1Se with a yield of 93.3%. LG2Se and LG3Se were synthesized with similar procedure with yields of 49.0% and 74.6% respectively. 1H NMR of LG1Se (DMSO-d6, ppm): δ = 7.76 (d, 4H), 7.34 (d, 4H), 3.82 (s, 4H), 3.62 (m, 2H), 3.32 (m, 4H), 3.14 (m, 4H), 2.84 (m, 4H), 1.36 (s, 36H), 1.20−1.30 (m, 24H). 1H NMR of LG2Se (DMSO-d6, ppm): δ = 7.73 (d, 4H), 7.35 (d, 4H), 4.16 (m, 4H), 3.82 (m, 6H), 3.40 (m, 4H), 3.00 (m, 4H), 2.87 (m, 8H), 2.83 (m, 4H), 1.36 (s, 72H), 1.10−1.70 (m, 36H). 1H NMR of LG3Se (DMSO-d6, ppm): δ = 7.73 (d, 4H), 7.35 (d, 4H), 4.14 (m, 6H), 3.82 (m, 12H), 3.30 (m, 4H), 2.98 (m, 12H), 2.86 (m, 20H), 1.36 (s, 144H), 1.10−1.70 (m, 84H). Preparation of Selenium−Platinum Coordination Dendrimers (DLG1Se/Pt, DLG2Se/Pt, DLG3Se/Pt). LG1Se (0.513 g, 0.47 mmol) was dissolved in 10 mL of dichloromethane. Then, 10 mL of trifluoroacetic acid was added under argon protected. After stirring for 30 min, the solution was concentrated with a rotary evaporator, and the product precipitated in ether. The solid sample DLG1Se was isolated by centrifugation and washed with ether for 3 times. After drying overnight, DLG1Se (11.4 mg, 0.01 mmol) and cisplatin (3.0 mg, 0.01 mmol) were mixed in 2 mL water and stirred at R.T. overnight to prepare 5 mM DLG1Se/Pt solution for further experiments. DLG2Se/Pt and DLG3Se/Pt were prepared with similar procedure. 1H NMR of DLG1Se (D2O, ppm): δ = 7.64 (d, 4H), 7.38 (d, 4H), 3.88 (m, 6H), 3.72 (m, 2H), 3.40−3.70 (m, 6H), 2.75 (m, 4H), 1.79 (m, 4H), 1.53 (m, 4H), 1.31 (m, 4H). MALDI-TOF: m/z 691.32 [M + H]+. 1H NMR of DLG1Se/Pt (D2O, ppm): δ = 7.68 (d, 4H), 7.60 (d, 4H), 4.48 (d, 2H), 4.20 (d, 2H), 3.88 (m, 2H), 3.72 (m, 2H), 3.40−3.70 (m, 6H), 2.82 (m, 4H), 1.81 (m, 4H), 1.57 (m, 4H), 1.33 (m, 4H). MALDI-TOF: m/z 884.25 [M + H]+. 1H NMR of DLG2Se (D2O, ppm): δ = 7.57 (d, 4H), 7.30 (d, 4H), 4.13 (m, 2H), 3.88 (m, 2H), 3.80 (m, 6H), 3.44 (m, 2H), 3.31 (m, 2H), 3.20 (m, 2H), 3.13 (m, 2H), 2.88 (m, 12H), 1.76 (m, 8H), 1.59 (m, 12H), 1.31
3. RESULTS AND DISCUSSION Synthesis of Selenium-Containing Lysine Dendrimers. To prepare selenium−platinum coordination dendrimers, we first synthesized selenium-containing dendrimers of different B
DOI: 10.1021/acsami.5b07877 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX
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ACS Applied Materials & Interfaces generations (Figure 1). As described by Appelhans et al., we synthesized L-lysine monodendrons up to the third generation
Figure 2. MALDI-TOF results and calculated molecular weight distribution of selenium−platinum coordination dendrimers of (a, b) the first, (c, d) the second, and (e, f) the third generation.
Figure 1. Chemical structures of selenium-containing dendrimers of the first to the third generation.
Pt]+ and [DLG3Se + Pt]+, respectively (Figure S3). Because platinum(II) usually coordinates with four ligands in a planar square structure, we need to find the ligands of platinum in the coordination dendrimers. 1 H NMR spectroscopy was used to study the structures of the selenium−platinum coordination dendrimers (Figure 3). After coordination between DLG1Se and cisplatin, three groups of peaks had clear shifts. Two double peaks of hydrogens on the phenyl group shifted from δ 7.63, 7.38 to δ 7.68, 7.60. Shifts of hydrogens on phenyl groups to lower field match the structure of the expected selenium−platinum
with N-Boc protected amino surface groups and a N-(2aminoethyl)amide group at the focal point (LG1-NH2, LG2NH2, LG3-NH2). To introduce selenium into the dendrimers, 4,4′-(selenobis(methylene))dibenzoic acid was synthesized and coupled with the lysine monodendrons in the ratio of 1:2. After the deprotection of N-Boc groups on the surface, target selenium-containing dendrimers were synthesized, which were called DLG1Se, DLG2Se, and DLG3Se, corresponding to the first, second, and third generation, respectively (Figure S1). Structures of Selenium−Platinum Coordination Dendrimers. Because selenium-containing dendrimers with the first to the third generation have been synthesized, cisplatin was introduced to coordinate with the dendrimers by simply mixing the two components together. Cisplatin was hard to dissolve in water, forming a turbid suspension. After coordination with selenium-containing dendrimers, transparent solutions were formed, indicating that the coordination improved the solubility of cisplatin in water (Figure S2). According to our previous study, selenium can coordinate with cisplatin, forming two possible structures: 1) Selenium replaces one of the chloro ligands of cisplatin, leaving other ligands unchanged. The active site of cisplatin is retained in this situation.35 2) Selenium as well as other potential ligands on selenium-containing molecules replaces both chloro and amino ligands of cisplatin, leading to the inactivation of the active site and the formation of a selenium−platinum active site.39,40 MALDI-TOF results supported the second hypothesis (Figure 2). For the complex of the first generation dendrimer and cisplatin, the main peak at m/z 884.25 matched the structure of [DLG1Se + Pt]+, supporting the hypothesis that both chloro and amino ligands of cisplatin were replaced. Similar results were obtained with DLG2Se and DLG3Se. After coordination with cisplatin, m/z 1395.64 and 2422.44 pointed to the structures of [DLG2Se +
Figure 3. 1H NMR and XPS results. (a) 1H NMR spectrum of the first generation selenium-containing dendrimer before and after coordination with cisplatin; XPS spectrum of (b) selenium and (c) platinum before and after coordination. C
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ACS Applied Materials & Interfaces coordination complex. The single peak of hydrogens on the methylene group next to selenium splits to two groups of double peaks, thereby shifting from δ 3.88 to δ 4.47, 4.20. Since the methylene group is between a selenium atom and a phenyl group, the rigid structure makes it difficult to rotate. When selenium coordinates with platinum, the chemical environment of the two hydrogens of the methylene group becomes different. Additionally, two hydrogens with different chemical shift couple to each other, which explained the split from a single peak to two groups of double peaks. Surprisingly, we also found a shift of the hydrogens on the methylene group next to terminal amine after coordination. The triple peak shifted from δ 2.75 to δ 2.82, which suggested a new bond forming at the terminal amino group. This result provides evidence for the structure in which the terminal amino groups of the seleniumcontaining dendrimers act as the ligands of platinum (Figure S4). Similar structures have been reported before indicating the possibility that platinum coordinates with selenium and nitrogen at the same time to form planar square structures.42−44 Although in the planar structure of DLG1Se, the terminal amino groups seemed far away from selenium, they could be close to selenium in twisted steric conformations. The amino groups in the dendrimers could interact with platinum by replacing the original ligands in cisplatin. In this way, platinum coordinates with selenium and two amino groups in the dendrimer to form the cation [DLG1Se + Pt]+, which was detected by MALDI-TOF. The other one of the four ligands of platinum could be chloride. In the 1H NMR spectrum of DLG2Se/Pt and DLG3Se/Pt, three groups of hydrogens also shifted to low field similar to what happened with DLG1Se/Pt (Figure S5). XPS results further confirmed the structures of selenium− platinum dendrimers. After coordination, the peak of selenium 3d orbitals shifted from 55.60 to 56.62 eV, indicating that selenium was oxidized in the coordination. If cisplatin did not coordinate with selenium, the peak of platinum in the XPS spectrum would not shift. If cisplatin formed coordination with selenium, but only one ligand of cisplatin was replaced, the redox reaction should be limited between selenium and platinum, suggesting the peak of platinum 4f orbitals to shift to lower binding energy. However, the peak of platinum 4f orbitals shifted from 72.67, 76.02 to 73.07, 76.57 eV. This slight increase indicated that reactions other than selenium−platinum coordination happened. Combining the results from MALDITOF, 1H NMR, and XPS, we can conclude that the structure we hypothesized is reasonable. Cellular Uptake of Selenium−Platinum Coordination Dendrimers. Cellular uptake is an important factor that affects the efficiency of a drug. Higher cellular uptake by cancer cells suggests the possibility of lower dosage. Cisplatin is a wellknown anticancer drug with high toxicity to normal cells, so the enhancement of selective cellular uptake can result in a lower dosage, alleviating the cytotoxicity to normal tissues. In an in vitro experiment, we tested the intracellular concentrations of platinum and selenium when cisplatin or dendrimers with different generations were introduced for incubation (Figure 4). The cellular uptake of platinum was higher for the three generations of selenium−platinum coordination dendrimers than for cisplatin, demonstrating the improvement of cellular uptake through incorporation of the platinum to dendrimers. This improvement probably results from a different uptake mechanism in case of cisplatin and dendrimers, respectively. Because cisplatin is a small hydrophobic molecule, it crosses the
Figure 4. Intracellular concentration of (a) Pt and (b) Se after HepG2 cells were incubated with 50 μM cisplatin, DLG1Se, DLG1Se/Pt, DLG2Se/Pt, and DLG3Se/Pt for 3 h.
cell membrane by diffusion. Since the dendrimers are more amphiphilic nanoparticles in water, they may cross the cell membrane by endocytosis.45 Another interesting phenomenon was that dendrimers with different generations showed different uptake. As generation increased, the uptake decreased. Since dendrimers of higher generations have larger sizes, they are more difficult to cross the membrane. Additionally, the cellular uptake of selenium was higher for the coordination dendrimers than for the selenium-containing dendrimers before coordination with platinum. Probably because coordination with platinum endowed selenium-containing dendrimers denser structures, forming aggregates with smaller sizes. Anticancer Activity of Selenium−platinum Coordination Dendrimers. We first tested the anticancer activity of the dendrimers against HepG2 liver cancer cells by MTT assay. Activity of selenium−platinum coordination dendrimers was compared with cisplatin and selenium-containing dendrimers. MTT results showed that selenium−platinum coordination dendrimers had similar anticancer activity to cisplatin, while selenium-containing dendrimer itself had little activity (Figure 5). Coordination with platinum endowed selenium-containing
Figure 5. MTT results of HepG2 cells after incubation with cisplatin, DLG1Se, DLG1Se/Pt, DLG2Se/Pt, and DLG3Se/Pt for 24 h.
dendrimers with anticancer activity, leading to the formation of a potential drug for cancer treatment. In the MTT data, coordination dendrimers with different generations also showed different anticancer activities. As the generation increased, the cytotoxicity decreased, which is reasonable as the selenium− platinum cores is buried deeper in the dendritic stucture. This difference makes it possible to control the cytotoxicity by tuning the generation of coordination dendrimers. We further tested the anticancer activity of the dendrimers through an in vivo study (Figure 6). 4T1 breast cancer cells were implanted to Balb/c mouse models. Dendrimers and cisplatin were injected every 3 days after the tumors had grown D
DOI: 10.1021/acsami.5b07877 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX
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Natural Science Foundation of China (21421064), and Tsinghua-Leuven joint project.
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(1) Gillies, E. R.; Frechet, J. M. J. Dendrimers and Dendritic Polymers in Drug Delivery. Drug Discovery Today 2005, 10, 35−43. (2) Bosman, A. W.; Janssen, H. M.; Meijer, E. W. About Dendrimers: Structure, Physical Properties, and Applications. Chem. Rev. 1999, 99, 1665−1688. (3) Shen, Y. Q.; Zhou, Z. X.; Sui, M. H.; Tang, J. B.; Xu, P. S.; Kirk, E. A. V.; Murdoch, W. J.; Fan, M. H.; Radosz, M. Charge-Reversal Polyamidoamine Dendrimer for Cascade Nuclear Drug Delivery. Nanomedicine 2010, 5, 1205−1217. (4) Cheng, Y. Y.; Zhao, L. B.; Li, Y. W.; Xu, T. W. Design of Biocompatible Dendrimers for Cancer Diagnosis and Therapy: Current Status and Future Perspectives. Chem. Soc. Rev. 2011, 40, 2673−2703. (5) Park, M. − H.; Agasti, S. S.; Creran, B.; Kim, C.; Rotello, V. M. Controlled and Sustained Release of Drugs from Dendrimer− Nanoparticle Composite Films. Adv. Mater. 2011, 23, 2839−2842. (6) Zhou, T.; Chen, P.; Niu, L.; Jin, J.; Liang, D. H.; Li, Z. B.; Yang, Z. Q.; Liu, D. S. pH-Responsive Size-Tunable Self-Assembled DNA Dendrimers. Angew. Chem., Int. Ed. 2012, 51, 11271−11274. (7) Morgan, M. T.; Nakanishi, Y.; Kroll, D. J.; Griset, A. P.; Carnahan, M. A.; Wathier, M.; Oberlies, N. H.; Manikumar, G.; Wani, M. C.; Grinstaff, M. W. Dendrimer-Encapsulated Camptothecins: Increased Solubility, Cellular Uptake, and Cellular Retention Affords Enhanced Anticancer Activity In vitro. Cancer Res. 2006, 66, 11913− 11921. (8) Matai, I.; Sachdev, A.; Gopinath, P. Self-Assembled Hybrids of Fluorescent Carbon Dots and PAMAM Dendrimers for Epirubicin Delivery and Intracellular Imaging. ACS Appl. Mater. Interfaces 2015, 7, 11423−11435. (9) Kong, L. D.; Alves, C. S.; Hou, W. X.; Qiu, J. R.; Mohwald, H.; Tomas, H.; Shi, X. Y. RGD Peptide-Modified Dendrimer-Entrapped Gold Nanoparticles Enable Highly Efficient and Specific Gene Delivery to Stem Cells. ACS Appl. Mater. Interfaces 2015, 7, 4833− 4843. (10) Mullen, D. G.; Holl, M. M. B. Heterogeneous Ligand− Nanoparticle Distributions: A Major Obstacle to Scientific Understanding and Commercial Translation. Acc. Chem. Res. 2011, 44, 1135−1145. (11) Biswas, S.; Dodwadkar, N. S.; Piroyan, A.; Torchilin, V. P. Surface Conjugation of Triphenylphosphonium to Target Poly(amidoamine) Dendrimers to Mitochondria. Biomaterials 2012, 33, 4773−4782. (12) Zhou, Z. X.; Ma, X. P.; Murphy, C. J.; Jin, E. L.; Sun, Q. H.; Shen, Y. Q.; Van Kirk, E. A.; Murdoch, W. J. Molecularly Precise Dendrimer−Drug Conjugates with Tunable Drug Release for Cancer Therapy. Angew. Chem., Int. Ed. 2014, 53, 10949−10955. (13) Caminade, A.-M.; Turrin, C.-O. Dendrimers for Drug Delivery. J. Mater. Chem. B 2014, 2, 4055−4066. (14) Medina, S. H.; El-Sayed, M. E. H. Dendrimers as Carriers for Delivery of Chemotherapeutic Agents. Chem. Rev. 2009, 109, 3141− 3157. (15) Kannan, R. M.; Nance, E.; Kannan, S.; Tomalia, D. A. Emerging Concepts in Dendrimer-Based Nanomedicine: from Design Principles to Clinical Applications. J. Intern. Med. 2014, 276, 579−617. (16) Huang, K. X.; Xu, H. B. Selenium: Its Chemistry, Biochemistry and Application in Life Science (in Chinese); Huazhong University of Science and Technology Press: Hubei, China, 2009. (17) Huang, X.; Liu, X. M.; Luo, Q.; Liu, J. Q.; Shen, J. C. Artificial Selenoenzymes: Designed andRedesigned. Chem. Soc. Rev. 2011, 40, 1171−1184. (18) Mugesh, G.; Singh, H. B. Synthetic Organoselenium Compounds as Antioxidants: Glutathione Peroxidase Activity. Chem. Soc. Rev. 2000, 29, 347−357. (19) Boyd, R. Selenium Stories. Nat. Chem. 2011, 3, 570.
Figure 6. In vivo study about anticancer activity of selenium−platinum coordination dendrimers. (a) Tumor volumes and (b) body weights of mice treated with different drugs.
for 10 days. Tumor volumes of mice injected with only selenium-containing dendrimers or PBS kept increasing throughout the whole experiment; while tumor volumes of mice injected with cisplatin or selenium−platinum coordination dendrimers just fluctuated around the original values, without increasing. This result demonstrated that selenium−platinum coordination dendrimers could inhibit tumor growth in a similar efficiency as cisplatin in mouse models. In the body weight measurement, mice injected with cisplatin lost weight rapidly, indicating a strong toxicity to normal tissues. In contrast, mice injected with coordination dendrimers kept their weight, similar to the control group injected PBS, demonstrating the low toxicity of the dendrimers compared with cisplatin.
4. CONCLUSIONS We have synthesized selenium−platinum coordination dendrimers with precise molecule structures via coordination between selenium-containing dendrimers and cisplatin. The dendrimers themselves showed controlled cellular uptake and anticancer activity by tuning the generation. The anticancer efficiency and low toxicity to normal tissues were indicated in an in vivo study. This work proposes a method to construct monodisperse dendrimers with anticancer activity on their own, which could broaden the application of dendrimers and selenium for cancer treatment.
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ASSOCIATED CONTENT
S Supporting Information *
Synthetic route of selenium-containing dendrimers. The color and turbidity changes after coordination between DLG1Se and cisplatin. MALDI-TOF spectrum of selenium−platinum coordination dendrimers. 1H NMR spectrum of seleniumcontaining dendrimers before and after coordination with cisplatin. The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/ acsami.5b07877. (PDF)
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REFERENCES
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Notes
The authors declare no competing financial interest.
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ACKNOWLEDGMENTS This study was funded by National Science Foundation for Distinguished Young Scholars (21425416), the National Natural Science Foundation of China (91427301), the National Basic Research Program of China (2013CB834502), the Foundation for Innovative Research Groups of the National E
DOI: 10.1021/acsami.5b07877 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX
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DOI: 10.1021/acsami.5b07877 ACS Appl. Mater. Interfaces XXXX, XXX, XXX−XXX
