サイズと架橋密度にナノスポンジ可変性
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概要
ペンダント機能を含む線形のポリエステルから共有架橋ナノ粒子のサイズと架橋密度を調整するためのプロセスについて説明します。合成パラメーター (ポリマーの分子量、ペンダント機能定款および架橋剤) を調整することによって薬物送達アプリケーションの必要なナノ粒子のサイズと架橋密度を実現できます。
Abstract
ペンダント エポキシド機能と制御寸法ナノスポンジの混入を含む線形のポリエステルの合成のためのプロトコルについて述べる。このアプローチは、得られたポリマーのペンダント機能化へキーである機能性ラクトンの合成から始まります。バレロラクトン (VL) とアリル-バレロラクトン (AVL) は、開環重合に共が。ポストキュア変更、ペンダント アリル グループの一部またはすべてにエポキシ基をインストールする使用されます。希薄溶液中の高分子と低分子芳香族ジアミン架橋剤目的ナノスポンジ サイズと架橋密度に基づくフォーム ナノ粒子にエポキシ樹脂アミン化学を採用します。ナノスポンジ サイズは、寸法と分布を決定する透過電子顕微鏡 (TEM) イメージングによって特徴付けられます。このメソッドは、高度調整可能なポリエステルが可変性ナノ粒子、小分子薬のカプセル化のため使用することができますを作成することが経路を提供します。バックボーンの性質のため、これらの粒子は疎水性小分子の広い範囲の制御放出の加水分解や酵素によって分解。
Introduction
これらナノシステム1の薬物放出プロファイルをガイドに影響を与える非常に重要なは分子間架橋結合に基づくナノ粒子のサイズと架橋密度を正確にチューニングします。すなわち、設計ナノスポンジ無依存異なるネットワーク密度の粒子を準備、前駆体ポリマーのペンダント機能および組み込まれる親水性の架橋剤の同等物に頼っています。このアプローチで前駆体および架橋剤、溶媒中の濃度はバルク ゲルではなく、個々 のサイズの形ナノ粒子に重要です。定量核磁気共鳴分光法 (NMR) 評価技術を利用して法人ペンダント機能と高分子の分子量の正確な測定可能します。ナノ粒子を形成、一度集中し、ナノゲルの性格を持つことがなく有機物の可溶化できます。
ナノ粒子ドラッグデリバリーの最近の研究はポリの使用に焦点を当てて (乳酸-co-グリコール酸) (PLGA) 自己組織化ナノ粒子2,3,4,5,6。PLGA 薬物送達アプリケーションに適している分解性エステルの連携があり、しばしばそのステルス特性7のため poly(ethylene glycol) (PEG) と組み合わせています。ただし、さらに高機能化有機物で、PLGA 粒子形成の自己組織化の性質のため粒子を溶解できません。PLGA ナノ粒子とは対照的は、提案されたメソッドは、定義されたサイズと形態、オーガニックで不安定であり水溶液1が低下するナノ粒子を形成共有結合で架橋を提供します。このアプローチの利点は、さらに化学的にナノスポンジ8の表面を高機能化する能力と有機溶剤の安定性は医薬品化合物1,9で粒子の後読み込みを使用できます。この方法では、水溶液に沈殿物によって疎水性小分子のカプセル化を実現できます。一緒に親水性の短い架橋ポリエステルのバックボーンの疎水性はこれらの粒子に体温でアモルファス文字を与えます。さらに、薬物の読み込み後、粒子は容易に注射で体内に水溶液中における微細懸濁液を形成できます。これらのポリエステルの nanosponges の合成用パラメーターを評価し、デザイン、サイズおよび形態の調節に非常に重要であるものを決定するこの作業における私たちの目標です。
Protocol
1. Synthesis and Characterization of AVL Place a magnetic stir bar inside a 2 neck 500 mL round bottom flask (Flask 1) and seal with an appropriate sized rubber septum and steel wire. Flame dry the flask to remove moisture by purging with nitrogen gas connected through an inlet needle and open outlet needle in the septum, while using a butane flame torch to gently heat the outside of the flask by moving the flame along the surface. Continue heating the entire flask by running the flame across the surface until moisture clouding the inside of the flask is not seen. Remove the flame and let the flask cool to room temperature while continuing the nitrogen flow throughout the reaction. Add 156.25 mL anhydrous tetrahydrofuran (THF) via a 30 mL syringe to Flask 1. Cool Flask 1 to -78 °C with a dry ice/acetone bath. Monitor the temperature with a thermometer throughout the reaction and add dry ice as needed to maintain -78 °C. Begin stirring the magnetic stir bar using a magnetic stir plate to create a gentle vortex. Add N,N-diisopropylethylamine (DIPA) (3.30 mL, 2.3 x 10-2 mol) via a 5 mL syringe, followed by the dropwise addition of 2.5 M n-Butyllithium (9.34 mL, 2.3 x 10-2 mol) via a 10 mL glass syringe equipped with a needle locking mechanism and metal needle to Flask 1. Continue to stir using a magnetic stir plate for 15 min at -78 °C. Flame dry (as described in step 1.1) and purge with argon gas (as described in step 1.1 with nitrogen gas) a 100 mL round bottom flask (Flask 2). Remove the argon gas inlet and outlet at the same time once the flask is cool enough to touch. Add 56 mL anhydrous THF via a 30 mL syringe and δ-valerolactone (VL) (1.97 mL, 2.1 x 10-2 mol) via a 5 mL syringe. Add the solution in Flask 2 to Flask 1 via a small cannula dropwise over 45 min while continuously stirring via a magnetic stir bar. Once Flask 2 is empty, remove the cannula and allow Flask 1 to continue stirring for 15 min at -78 °C. Flame dry (as described in step 1.1) and purge with argon gas (as described in step 1.1 with nitrogen gas) a 25 mL round bottom flask (Flask 3). Remove the argon gas inlet and outlet at the same time once the flask is cool enough to touch, to maintain positive pressure inside the flask. Add ally bromide (2.02 mL, 2.3 x 10-2 mol) and hexamethyphosphoramide (HMPA) (4.43 mL, 2.5 x 10-2 mol) each via a 5 mL syringe. Add Flask 3 to Flask 1 via a small cannula dropwise. Once Flask 3 is empty, remove the cannula. Remove as much dry ice and cold acetone as possible from the dry ice/acetone bath in which Flask 1 is submerged using a scoop and plastic cup. Replace with room temperature acetone to raise the bath to -40 °C and allow Flask 1 to continue stirring for 2 h while monitoring the temperature. If the temperature increases above -40 °C, add a few pieces of dry ice to cool the acetone. Warm to -10 °C by removing the cold acetone and dry ice and replace with room temperature acetone. Remove the septum from Flask 1 and quench the reaction with a 150 mL saturated ammonium chloride solution while stirring via a magnetic stir bar. Place Flask 1 in a freezer at -20 °C overnight for storage. Remove Flask 1 from the freezer and allow to warm to room temperature. Pour the solution from Flask 1 into a 500 mL separatory funnel. Add 50 mL dichloromethane (DCM), cap the separatory funnel, and rock gently to mix the DCM and aqueous/THF mixture to extract the product into the organic layer. Collect the organic layer into a 500 mL beaker containing an appropriately sized magnetic stir bar by opening the separatory funnel stopcock and set aside. Repeat two times. Collect all the organics into the same beaker and stir over magnesium sulfate (to remove any residual water) using a magnetic stir plate until the magnesium sulfate no longer clumps when added to solution. Discard the aqueous waste. Remove the magnesium sulfate solid from the organic product solution by using a filter paper inside a glass funnel and collect the organics in a 250 mL round bottom flask. Rinse the filter paper and solid magnesium sulfate with excess DCM to ensure that all the product is collected. Remove the solvent from the product by rotary evaporation while heating at 30 °C and using a water aspirator as the vacuum source. Purify the crude product by column chromatography10 using a silica gel as the stationary phase and eluting beginning with 3% ethyl acetate/hexanes for 1 column volume (CV), increasing the gradient to 29% ethyl acetate/hexanes over 5 CVs. Collect the fractions in 16 x 150 mm2 borosilicate glass tubes. Perform thin layer chromatography using 20% ethyl acetate/hexanes as eluent to determine the product fractions. Combine all product fractions into an appropriately sized round bottom flask and remove the solvent using rotary evaporation at 40 °C. Transfer to a pre-weighed product vial and place under a high vacuum at 0.05 torr to obtain pure AVL. Characterize the product by 1H NMR11 (CDCl3, 400 MHz): δ 5.75 (m, 1H), 5.06 (m, 2H), 4.26 (m, 2H), 2.54 (m, 3H), 2.28 (m, 1H), 2.03 (m, 1H), 1.87 (m, 1H), 1.54 (m, 1H). Yield: 2.07 g (70.56%). 2. Synthesis and Characterization of VL- co- AVL Flame dry and purge with nitrogen gas a 25 mL round bottom flask equipped with a magnetic stir bar and septum. Flame dry the flask to remove moisture by purging with nitrogen gas connected through an inlet needle and open outlet needle in the septum, while using a butane flame torch to gently heat the outside of the flask by moving the flame along the surface. Continue heating the entire flask by running the flame across the surface until moisture clouding the inside of the flask is not seen. Remove the flame and let the flask cool to room temperature while continuing the nitrogen flow throughout the reaction. Quickly remove the septum from the round bottom and add tin(II) triflate (2.5 mg, 5.9 x 10-6 mol) to the very bottom of the flask using a spatula. Replace the septum. Add 3-methyl-1-butanol (72.6 µL, 6.6 x 10-3 mol) via a 100 µL microsyringe and 1.33 mL anhydrous DCM via a 2 mL syringe sequentially. Stir via a magnetic stir plate for 10 min. Add AVL (0.48 mL, 3.7 x 10-3 mol) and VL (1.37 mL, 1.4 x 10-2 mol) sequentially via a syringe. Allow to continue stirring for 18 – 20 h. NOTE: The AVL and VL percentage in the final copolymer can be altered by stoichiometry in this step. Quench the reaction by adding ~5 mL methanol (MeOH). Add ~100 mg solid-support tin scavenger and stir for 2 h. Filter by gravity filtration to remove the solid. Remove the solvent under rotary evaporation with a water aspirator as the vacuum source while heating at 30 °C until the solution is viscous. Precipitate the solution dropwise into 500 mL cold MeOH (chilled with dry ice for at least 1 h) to produce flakes of white solid. Filter the solution by vacuum filtration into a funnel containing a fritted glass disc with filter paper to collect the solid. NOTE: If precipitation produces a cloudy supernatant or fine powder which goes through the filter paper, then the product solution is too dilute. All supernatant solvent should be removed by rotary evaporation with a water aspirator as the vacuum source while heating at 30 °C until the solution is viscous and then precipitation should be performed again. Transfer the solid product to a pre-weighed vial via a spatula and dry overnight via high vacuum pressure of 0.05 torr to collect the white, flaky solid. Characterize the polymer by 1H NMR11 (CDCl3, 400 MHz): δ 5.71 (m, 1H), 5.03 (t, 2H), 4.08 (m, 4H), 3.65 (t, 2H), 2.15 – 2.50 (m, 5H), 1.47-1.78 (m, 9H), 0.91 (d, 6H). 81.42% VL, 18.58% AVL, 2,940 g/mol, 578 g/mol repeat unit of AVL. Yield: 1.43 g, (73.43%). 3. Post-polymerization Epoxidation to Produce Epoxy-valerolactone (EVL) Copolymer Units Add VL-co-AVL copolymer (500 mg, 1.7 x 10-4 mol, 2,940 g/mol) to a 6-dram vial with a magnetic stir bar. Add 6.15 mL anhydrous DCM to the vial and vortex to solubilize the polymer. Add meta-chloroperoxybenzoic acid (mCPBA) (74.53 mg, 4.3 x 10-4 mol) to a second 6-dram vial. Add 6.15 mL anhydrous DCM and vortex until the mCPBA is solubilized completely. NOTE: The conversion ratio of allyls to epoxides can be varied by altering the stoichiometry in this step. The final allyl concentration in the solvent should be 0.065 M. Transfer the mCPBA solution to the VL-AVL solution. Cap the reaction and cover with a plastic paraffin film. Allow to stir for 48 h. Transfer the reaction mixture to a 50 mL separatory funnel. Add 15 mL saturated sodium bicarbonate, cap the separatory funnel, and rock gently to mix. Collect the organic layer containing the product into a 50 mL Erlenmeyer flask with an appropriate sized magnetic stir bar (product flask). Add 5 mL DCM to the aqueous layer that is still in the separatory funnel, cap, and then rock gently. Collect the organics into the product flask. Discard the aqueous waste. Transfer the organic layer back into a separatory funnel. Repeat this aqueous wash two times. Add magnesium sulfate (to remove any residual water) to the product flask while stirring over a magnetic stir plate. Continue adding small scoops of magnesium sulfate until it no longer clumps when added. Use a glass funnel fitted with a filter paper to remove the solid magnesium sulfate while transferring the mixture to a 50 mL round bottom flask. Remove the solvent by rotary evaporation with a water aspirator as the vacuum source and heating at 25 °C. Transfer the contents of the round bottom flask to a pre-weighed product vial and remove the solvent by rotary evaporation. Place on high vacuum at 0.05 torr overnight to produce a white, waxy solid. Characterize by 1H NMR11 (CDCl3, 400 MHz): δ 5.71 (m, 1H), 5.03 (t, 2H), 4.08 (m, 4H), 3.65 (t, 2H), 2.94 (d, 1H), 2.90 (s, 1H), 2.74 (s, 1H), 2.15-2.50 (m, 5H), 1.47-1.78 (m, 9H), 0.92 (d, 6H). 84.53% VL, 9.65% AVL, 5.82% EVL, 2,855 g/mol, 1,841 g/mol repeat unit of EVL. Yield: 417.3 mg, (83.46%). 4. Nanosponge Synthesis and Characterization Dissolve the VL-co-AVL-co-EVL polymer (200 mg, 7.0 x 10-5 mol, 2,855 g/mol) in 20.01 mL anhydrous DCM for an epoxide concentration of 0.0054 M. Transfer to a 100 mL round bottom flask with a 14/20 neck. NOTE: To catalyze the reaction, 100 µL aqueous saturated sodium bicarbonate can be added in this step. Place the reaction flask in an oil bath at 50 °C. Stir the solution with a fast vortex and add 2,2'-(ethylenedioxy)bis(ethylamine) (21.45 µL, 2.9 10-4 mol) via a microsyringe dropwise. Fit the neck of the flask with a water-jacketed condenser with cool water flowing through it, fitted with a 14/20 neck adapter, and reflux the solution for 12 h. Ensure a very tight seal between the neck of the flask and the condenser to avoid solvent evaporation. Remove excess solvent from the reaction flask by rotary evaporation at 25 °C until a viscous solution is obtained. Place a large magnetic stir bar into a 2 L beaker. Cut an approximately six-inch section of 10 K molecular weight cut-off (MWCO) dialysis tubing and fold one end then close with a dialysis clip. Transfer the product to 10 K MWCO dialysis tubing. Rinse the flask with excess DCM and transfer it to the tubing.Fold the top of the tubing and close with a dialysis clip that has a wire for hanging. Hang the dialysis tubing on the side of the beaker using the wire and fill the beaker with DCM until the dialysis tubing is completely submerged. Place on a magnetic stir plate and stir gently. Cover the beaker with aluminum foil to prevent solvent evaporation. Remove the solvent by pouring into a waste container and replace with fresh DCM three times daily for 48 h to remove the unreacted polymer and crosslinker. Remove all solvent from the beaker and transfer the contents of the dialysis tubing to a 10 mL syringe fitted with a 0.45 µm polytetrafluoroethylene (PTFE) syringe filter. Push the solution through the filter directly into a pre-weighed product vial to remove any remaining impurities. Remove the solvent by rotary evaporation at 25 °C, then place on high vacuum at 0.05 torr overnight to collect the light yellow, waxy solid. Characterize by 1H NMR11 (CDCl3, 400 MHz): δ 5.71 (m, 1H), 5.03 (t, 2H), 4.08 (m, 4H), 3.60-3.67 (t, 14H), 2.94 (d, 1H), 2.90 (s, 1H), 2.74 (s, 1H), 2.15-2.50 (m, 5H), 1.47-1.78 (m, 9H), 0.92 (d, 6H). Yield: 176.9 mg (88.45%). 5. TEM Imaging of Nanosponge Morphology and Size Filter 5 mL cell culture water through a 0.2 µm PTFE syringe filter. Place 0.5 mg nanosponges into a 1.5 mL centrifuge tube. Add 1 mL filtered cell culture water. Use a probe sonicator (20 kHz, 40 a) to sonicate the solution with 2 s bursts 4 – 5 times at room temperature until the particles have developed a fine suspension. Do not use prolonged sonication or let the solution heat up as this will cause aggregation. Add 30 mg phosphotungstic acid hydrate (PTA) to 1 mL filtered cell culture water in a 1.5 mL centrifuge tube. Vortex on the highest setting for 10 s or until the PTA is completely solubilized to produce 3% PTA solution. Use a 1 mL syringe with 22 G needle to draw up 0.5 mL 3% PTA solution. Add 4 drops of the 3% PTA solution to the particles and vortex on the highest setting for 10 s. Use a pair of self-closing tweezers to pick up a TEM grid then dip it into the particles solution quickly, three times. Let the grid dry for 5 h under a cover to reduce dust collection on the grid. Perform TEM imaging12 of the sample using high contrast and 40 µm objective.
Representative Results
ナノスポンジの合成パラメーターとその結果のサイズの関係を評価するには、各高分子前駆体の濃度とペンダントの機能は重要です。図 1で、12 h の DCM で両方前駆体高分子/ジアミン誘導体の架橋を組み込んだ後、その nanosponges の successfulsynthetic 方式が還流条件下で実施は。ソリューションのエポキシド濃度も離散的な粒子の形成に重要です。?…
Discussion
再現可能なナノスポンジ サイズを取得は、薬物送達アプリケーションに不可欠です。重合とナノスポンジ合成における複数パラメーターは、結果として得られる粒子のサイズと架橋密度を影響します。3 つの重要なパラメーターは、我々 の分析で識別された: 架橋剤及びエポキシ樹脂ペンダント機能高分子の分子量。分子量とエポキシド ナノスポンジ合成機能の範囲を生成するために、VL-<em…
開示
The authors have nothing to disclose.
Acknowledgements
LK は国立科学財団大学院研究フェローシップ ・ プログラム (DGE-1445197) とヴァンダービルト大学化学部門からの資金のために感謝しています。LK と EH オシリス TEM 装置 (NSF EPS 1004083) のための資金に感謝したいと思います。
Materials
| 2,2'-(Ethylenedioxy)bis(ethylamine) | Sigma-Aldrich | 385506-100ML | |
| 3-methyl-1-butanol | Sigma-Aldrich | 309435-100ML | anhydrous, ≥99% |
| Acetone | Sigma-Aldrich | 179124-4L | |
| Allyl bromide | Sigma-Aldrich | A29585-5G | ≥99% |
| Ammonium chloride | Fisher Scientific | A661-500 | saturated solution in DI water |
| Cell culture water | Sigma-Aldrich | W3500-500ML | Filtered through 0.45 μm syringe filter |
| Dichloromethane (DCM) | Sigma-Aldrich | 270997-100ML | anhydrous, ≥99%, contains 40-150 ppm amylene as stabilizer |
| Ethyl Acetate | Fisher Scientific | E145SK-4 | |
| EZFlow 0.2 μm Syringe Filter | Foxx Life Sciences | 386-2116-OEM | Hydrophillic PTFE, 13 mm |
| EZFlow 0.45 μm Syringe Filter | Foxx Life Sciences | 386-3126-OEM | Hydrophillic PTFE, 25 mm |
| Fisherbrand Disposable Borosilicate Glass Test Tubes with Plain End | Fisher Scientific | 14-961-31 | |
| Fisherbrand Microcentrifuge Tubes | Fisher Scientific | 14-666-318 | 1.5 mL |
| Hamilton Microliter Syringe, 100 μL | Hamilton Company | 80600 | Model 710 N SYR, Cemented NDL, 22s ga, 2 in, point style 2 |
| Hexamethylphosphoramide | Sigma-Aldrich | H11602-100G | ≥99%, contains ≤1000 ppm propylene oxide as stabilizer |
| Hexanes | Fisher Scientific | H292-4 | |
| Magnesium sulfate anhydrous | Fisher Scientific | M65-500 | |
| Meta-chloroperoxybenzoic acid | Sigma-Aldrich | 273031-100G | Purified to ≥99% by buffer wash |
| Methanol (MeOH) | Sigma-Aldrich | 322415-100ML | anhydrous, ≥99% |
| N-butyllithium solution | Sigma-Aldrich | 230707-100ML | 2.5 M in hexanes |
| N,N-diisopropylethylamine | Sigma-Aldrich | 550043-500ML | ≥99% |
| Parafilm M | Sigma-Aldrich | P7793-1EA | |
| PELCO Pro Reverse (Self-Closing) Tweezers | Ted Pella, Inc. | 5375-NM | |
| Phosphotungstic acid hydrate | Alfa Aesar | 40116 | |
| Q55 Sonicator | Qsonica | Q55-110 | 55 Watts, 20 kHz |
| SiliaMetS Cysteine | Silicycle | R80530B-10g | |
| SnakeSkin Dialysis Clips | Thermo Scientific | 68011 | |
| SnakeSkin Dialysis Tubing, 10K MWCO | Thermo Scientific | 68100 | |
| Sodium bicarbonate | Fisher Scientific | 5233-500 | saturated solution in DI water |
| TEM grid | Ted Pella, Inc. | 01822-F | Ultrathin Carbon Type-A, 400 mesh, Copper, approx. grid hole size: 42µm |
| Tetrahydrofuran (THF) | Sigma-Aldrich | 401757-1L | Anhydrous, ≥99.9%, inhibitor-free |
| Tin(II) trifluoromethanesulfonate | Sigma-Aldrich | 388122-1G | |
| Vortex-Genie 2 | Scientific Industries | SI-0236 | |
| Whatman Filter Paper, Grade 1 | Fisher Scientific | 09-805H | Circles, 185 mm |
| δ-valerolactone | Sigma-Aldrich | 389579-100ML | Purified by vacuum distillation |
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