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Method Article
ポリ (アクリル酸ペンタフルオロフェニル) の準備のためのプロトコル (poly(PFPA)) 接木シリカビーズを提示。Poly(PFPA) 機能性表面は抗体を固定化し、正常に免疫沈降法による蛋白質の分離のために使用します。
ポリ (アクリル酸ペンタフルオロフェニル) を準備する簡単な方法を示す (poly(PFPA)) は、抗体の固定化とそれに続く免疫沈降 (IP) アプリケーションのシリカビーズを移植しました。Poly(PFPA) グラフト表面は、単純な 2 段階のプロセスを介して用意しています。最初のステップで 3-アミノプロピルトリエトキシシラン (APTES) は、シリカ表面にリンカー分子として預けられます。2 番目のステップでペンタフルオロフェニル (PFP) 単位間の交換反応によってリンカー分子に可逆的付加と断片化チェーン転送 (いかだ) 重合により合成した poly(PFPA) ホモポリマーを移植で、ポリマーと APTES のアミン グループ。APTES とシリカ粒子は x 線光電子分光法 (XPS) により確認し同様、粒子サイズの変更によって監視 poly(PFPA) の沈着は、動的光散乱 (DLS) を介して測定。ビーズ、アミン官能基化 poly(ethylene glycol) と poly(PFPA) の一部代替の表面の親水性を向上させる (アミノ PEG) が行われます。ペグ-置換 poly(PFPA) は、ビーズが IP アプリケーションのための抗体を固定化し、シリカを移植しました。デモで、タンパク質キナーゼ (PKR) rna 抗体を採用、IP 効率は西部にしみが付くことによって決定されます。分析の結果, 抗体固定化ビーズを無指定蛋白質の相互作用は最小限、PKR を豊かに使用確かにできます。
反応性ポリマー ブラシは、近年多くの関心を受けています。検出と分離1,2,3,4などの分野でのアプリケーションと非アクティブなサーフェスを作成する有機又は無機の物質に機能分子を固定化する使用することができます。 5。報告された反応性高分子の中でペンタフルオロフェニル エステル単位を含む、アミンと加水分解6に向けて耐反応性が高いため特に便利です。1 つのようなポリマーは poly(PFPA) と、それはプライマリまたはセカンダリのアミン7,8,9,10を含む分子と容易に官能の後重合をすることができます。1 つの例で、poly(PFPA) ブラシした光応答性表面7を作成するアミノ スピロピランと反応しました。
Poly(PFPA) とその応用の準備は前出版物6,7,8,9,10、11,12 の番号に記載されています。 ,13,14,15,16,17。特に、Theato と同僚は報告「移植」と""方法7,8,10、11,12から移植の両方を介して poly(PFPA) ブラシの合成.「接木する」アプローチは、ポリ (メチルシルセスキオキサン) の-ポリ (アクリル酸ペンタフルオロフェニル) (poly(MSSQ-PFPA)) ハイブリッド ・ ポリマーは合成8,10、11,12。Poly(MSSQ) コンポーネントはフォーム数材料表面上ブラシ層を形成するコンポーネントの poly(PFPA) をように別の有機・無機表面と密着できた。「接木から」アプローチ、表面は可逆的付加を開始され、断片化チェーン転送 (SI ・ ラフト) 重合を用いて poly(PFPA) ブラシ7を準備します。この場合、表面固定化連鎖移動剤 (SI CTA) 最初共有についたシリカ シラン反応による基板。固定化 SI CTA は、基板に安定した共有結合のリンケージを持つ密集 poly(PFPA) ブラシを生成する PFPA モノマーの SI ・ ラフト重合し参加しました。
SI ・ ラフト重合により合成した poly(PFPA) ブラシを活用し、最近移植 poly(PFPA) シリカ粒子やタンパク質精製18で、後続のアプリケーションにおける抗体の固定化を示した。IP で現在の蛋白質の分離に関連する問題の数を解決する抗体固定化のための poly(PFPA) ブラシの使用が見つかりました。従来の IP は、抗体固定化19,20,21のタンパク質 A/G リンカーとしての使用に依存します。タンパク質 A/G の特定の方向で接続する抗体を使用、高いターゲット抗原回復効率が達成されました。ただし、タンパク質 A/G の使用苦しんでいる抗体の損失と同様、非特異的タンパク質間相互作用タンパク質の回収、どちらもはバック グラウンド ノイズの高レベルに貢献中。これらの欠点を解決するには、しっかりサポートする抗体の直接架橋検討22,23,24をされています。このような技術の効率は架橋抗体のランダムな向きがあるため通常は低くなります。接木 poly(PFPA) 基板の抗体の固定化は永久、PFP ユニットと抗体のアミン機能間の交換反応によって達成されます。抗体の向きはまだランダムが、システム多く反応 PFP サイト、重合度によって制御を持っていることから寄与します。さらに、我々 はアミノ止め釘と PFP 単位の部分的な置換によることを示した表面親水性調整できるさらにシステム18のタンパク質回収効率を向上します。全体的にみて、多くのクリーナーの背景と同様、合理的な効率で従来の IP へ有効な代わりをする接木 poly(PFPA) シリカ粒子が示されていた。
この貢献抗体固定化と IP アプリケーションを poly(PFPA) グラフト表面を準備する方法を報告する.単純な 2 段階のプロセスで図 1に示すように、APTES のリンカー分子最初に到着したシリカ表面にし、poly(PFPA) 高分子に PFP ユニット間反応によってリンカー分子に接続した、ポリマーと APTES のアミン機能。本調製法は基板表面に poly(PFPA) の永久的な架橋が可能が SI CTA 合成と poly(PFPA) ブラシの SI ・ ラフト重合に関連する多くの合併症を回避します。アミノ ペグの PFP ユニットの部分置換実行できますが、ポリマー ブラシ表面特性の微調整可能します。従って準備 poly(PFPA) 接木シリカビーズを抗体を固定化して IP を介したタンパク質の濃縮に使用できますを示します。詳細なビード作製手順、抗体固定化と IP テストは、この資料に記載されて、読者を求めて興味従来タンパク質 A/G に代わるベースの IP。
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1. Poly(PFPA) ホモポリマーの準備
2. Poly(PFPA) の準備機能 SiO2ビーズ
3. SiO2の準備ペグ-置換 Poly(PFPA) をグラフトしたビーズ
4. 抗体固定化 Poly(PFPA) の接ぎ木 SiO2ビーズ
注: 同じ手順は、poly(PFPA) %peg 置換に関係なく用いられます。TDW で PBS タブレットを溶解することにより、リン酸緩衝生理食塩水 (PBS) を準備します。0.1% (v/v) リン酸緩衝生理食塩水でトゥイーン 20 (pbst;) を準備するには、PBS に Tween 20 1/1000 を追加します。
5. 細胞換散および免疫沈降
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Poly(PFPA) の準備のための回路図と SiO2ビーズおよびペグなし置換は図 1に示します。APTES と poly(PFPA) プロセス、裸の SiO2ビーズを移植を監視する APTES 機能 SiO2ビーズと poly(PFPA) 接木 SiO2ビーズは DLS (図 2) と XPS (図 3) によって特徴付けられます。ビーズの IP 効率は西部に?...
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Poly(PFPA) の合成は接ぎ木 SiO2ビーズは図 1に示します。リンカー分子として APTES を採用し、単純な 2 段階のプロセスを介して SiO2基板に移植した poly(PFPA) ブラシを用意できます。PFP の単位のいくつかが APTES との反応を犠牲に、多数の PFP ユニットがアミノ ペグまたは抗体のいずれかで後の反応に利用可能なままと予想します。PFP グループは、poly(PFPA) ブ?...
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著者が明らかに何もありません。
この作品は、防衛開発 (グラント号の代理店によって支えられました。UD170039ID)。
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Name | Company | Catalog Number | Comments |
2,2-Azobisisobutyronitrile, 99% | Daejung Chemicals | 1102-4405 | |
Methyl alcohol for HPLC, 99.9% | Duksan Pure Chemicals | d62 | |
Phenylmagnesium bromide solution 1.0 M in THF | Sigma-Aldrich | 331376 | |
Carbon disulfide anhydrous, ≥99% | Sigma-Aldrich | 335266 | |
Benzyl bromide, 98% | Sigma-Aldrich | B17905 | |
Petroleum ether, 90% | Samchun Chemicals | P0220 | |
Ethyl ether, 99% | Daejung Chemicals | 4025-4404 | |
Magnesium sulfate anhydrous, powder, 99% | Daejung Chemicals | 5514-4405 | |
Pentafluorophenyl acrylate | Santa Cruz Biotechnology | sc-264001 | contains inhibitor |
Aluminium oxide, activated, basic, Brockmann I | Sigma-Aldrich | 199443 | |
Sodium Chloride (NaCl) | Daejung Chemicals | 7548-4400 | |
Anisole anhydrous, 99.7% | Sigma-Aldrich | 296295 | |
Silica nanoparticle | Microparticles GmbH | SiO2-R-0.7 | 5% w/v aqueous suspension |
3-Aminopropyltrimethoxysilane, >96.0% | Tokyo Chemical Industry | T1255 | |
Dimethyl sulfoxide for HPLC, ≥99.7% | Sigma-Aldrich | 34869 | |
Amino-terminated poly(ethylene glycol) methyl ether | Polymer Source | P16082-EGOCH3NH2 | |
Phosphate buffered saline tablet | Takara | T9181 | |
Tween-20 | Calbiochem | 9480 | |
Tris-HCl (pH 8.0) | Invitrogen | AM9855G | |
KCl | Invitrogen | AM9640G | |
NP-40 | VWR | E109-50ML | |
Glycerol | Invitrogen | 15514-011 | |
Dithiothreitol | Biosesang | D1037 | |
Protease inhibitor | Merck | 535140-1MLCN | |
Bromo phenol blue | Sigma-Aldrich | B5525-5G | |
Tris-HCl (pH 6.8) | Biosolution | BT033 | |
Sodium dodecyl sulfate | Biosolution | BS003 | |
2-Mercaptoethanol | Gibco | 21985-023 | |
PKR Antibody | Cell Signaling Technology | 12297S | |
GAPDH Antibody | Santa Cruz Biotechnology | sc-32233 | |
Normal Rabbit IgG | Cell Signaling Technology | 2729S | |
HeLa | Korea Cell Line Bank | 10002 | |
Sonicator | DAIHAN Scientific | WUC-D10H | |
Ultrasonicator | BMBio | BR2006A | |
Centrifuge I | Eppendorf | 5424 R | |
Centrifuge II | LABOGENE | 1736R | |
Rotator | FINEPCR | ROTATOR/AG | |
Vacuum oven | DAIHAN Scientific | ThermoStable OV-30 | |
Gel permeation chromatography (THF) | Agilent Technologies | 1260 Infinity II | |
X-ray photoelectron spectrometer | Thermo VG Scientific | Sigma Probe | |
Dynamic light scattering | Malvern Instruments | ZEN 3690 |
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An erratum was issued for: Preparation of Poly(pentafluorophenyl acrylate) Functionalized SiO2 Beads for Protein Purification. Throughout the article, the term "3-aminopropyltriethoxysilane" has been replaced with "3-aminopropyltrimethoxysilane", and "APTES" with "APTMS".
The Keywords were updated from:
Poly(pentafluorophenyl acrylate), 3-aminopropyltriethoxysilane, reactive polymer brush, post-polymerization functionalization, antibody immobilization, immunoprecipitation
to:
Poly(pentafluorophenyl acrylate), 3-aminopropyltrimethoxysilane, reactive polymer brush, post-polymerization functionalization, antibody immobilization, immunoprecipitation
The Abstract was updated from:
We demonstrate a simple method to prepare poly(pentafluorophenyl acrylate) (poly(PFPA)) grafted silica beads for antibody immobilization and subsequent immunoprecipitation (IP) application. The poly(PFPA) grafted surface is prepared via a simple two-step process. In the first step, 3-aminopropyltriethoxysilane (APTES) is deposited as a linker molecule onto the silica surface. In the second step, poly(PFPA) homopolymer, synthesized via the reversible addition and fragmentation chain transfer (RAFT) polymerization, is grafted to the linker molecule through the exchange reaction between the pentafluorophenyl (PFP) units on the polymer and the amine groups on APTES. The deposition of APTES and poly(PFPA) on the silica particles are confirmed by X-ray photoelectron spectroscopy (XPS), as well as monitored by the particle size change measured via dynamic light scattering (DLS). To improve the surface hydrophilicity of the beads, partial substitution of poly(PFPA) with amine-functionalized poly(ethylene glycol) (amino-PEG) is also performed. The PEG-substituted poly(PFPA) grafted silica beads are then immobilized with antibodies for IP application. For demonstration, an antibody against protein kinase RNA-activated (PKR) is employed, and IP efficiency is determined by Western blotting. The analysis results show that the antibody immobilized beads can indeed be used to enrich PKR while non-specific protein interactions are minimal.
to:
We demonstrate a simple method to prepare poly(pentafluorophenyl acrylate) (poly(PFPA)) grafted silica beads for antibody immobilization and subsequent immunoprecipitation (IP) application. The poly(PFPA) grafted surface is prepared via a simple two-step process. In the first step, 3-aminopropyltrimethoxysilane (APTMS) is deposited as a linker molecule onto the silica surface. In the second step, poly(PFPA) homopolymer, synthesized via the reversible addition and fragmentation chain transfer (RAFT) polymerization, is grafted to the linker molecule through the exchange reaction between the pentafluorophenyl (PFP) units on the polymer and the amine groups on APTMS. The deposition of APTMS and poly(PFPA) on the silica particles are confirmed by X-ray photoelectron spectroscopy (XPS), as well as monitored by the particle size change measured via dynamic light scattering (DLS). To improve the surface hydrophilicity of the beads, partial substitution of poly(PFPA) with amine-functionalized poly(ethylene glycol) (amino-PEG) is also performed. The PEG-substituted poly(PFPA) grafted silica beads are then immobilized with antibodies for IP application. For demonstration, an antibody against protein kinase RNA-activated (PKR) is employed, and IP efficiency is determined by Western blotting. The analysis results show that the antibody immobilized beads can indeed be used to enrich PKR while non-specific protein interactions are minimal.
The fourth paragraph of the Introduction was updated from:
In this contribution, we report an alternative method to prepare poly(PFPA) grafted surface for antibody immobilization and IP application. In a simple two-step process, as illustrated in Figure 1, an APTES linker molecule is first deposited onto the silica surface, then the poly(PFPA) polymer is covalently attached to the linker molecule through the reaction between the PFP units on the polymer and the amine functions on APTES. This preparation method allows for the permanent crosslinking of poly(PFPA) to a substrate surface, but avoids the many complications associated with SI-CTA synthesis and SI-RAFT polymerization of poly(PFPA) brushes. Partial substitution of the PFP units with amino-PEG can still be performed, allowing fine-tuning of the polymer brush surface properties. We show the poly(PFPA) grafted silica beads thus prepared can be immobilized with antibodies and used for protein enrichment via IP. The detailed bead preparation procedure, antibody immobilization, and IP testing are documented in this article, for readers interested in seeking an alternative to conventional Protein A/G based IP.
to:
In this contribution, we report an alternative method to prepare poly(PFPA) grafted surface for antibody immobilization and IP application. In a simple two-step process, as illustrated in Figure 1, an APTMS linker molecule is first deposited onto the silica surface, then the poly(PFPA) polymer is covalently attached to the linker molecule through the reaction between the PFP units on the polymer and the amine functions on APTMS. This preparation method allows for the permanent crosslinking of poly(PFPA) to a substrate surface, but avoids the many complications associated with SI-CTA synthesis and SI-RAFT polymerization of poly(PFPA) brushes. Partial substitution of the PFP units with amino-PEG can still be performed, allowing fine-tuning of the polymer brush surface properties. We show the poly(PFPA) grafted silica beads thus prepared can be immobilized with antibodies and used for protein enrichment via IP. The detailed bead preparation procedure, antibody immobilization, and IP testing are documented in this article, for readers interested in seeking an alternative to conventional Protein A/G based IP.
Step 2.1 of the Protocol was updated from:
Treatment of SiO2 beads with APTES
to:
Treatment of SiO2 beads with APTMS
Step 2.1.1 of the Protocol was updated from:
SiO2 particles are available in the form of a 5% (w/v) aqueous suspension. Combine 0.8 mL of SiO2 suspension with 40 mg of APTES and 8 mL of methanol in a 20 mL scintillation vial equipped with a stir bar.
to:
SiO2 particles are available in the form of a 5% (w/v) aqueous suspension. Combine 0.8 mL of SiO2 suspension with 40 mg of APTMS and 8 mL of methanol in a 20 mL scintillation vial equipped with a stir bar.
Step 2.1.3 of the Protocol was updated from:
Transfer the solution to a conical tube. To isolate the APTES functionalized SiO2 beads, centrifuge the solution at 10,000 x g for 5 min, then remove the supernatant. Wash the beads by re-dispersing them in 3 mL of fresh methanol. Shake the tube by hand for mixing, but if necessary, improve the dispersion by sonication in a water bath for a few seconds. Centrifuge the beads at 10,000 x g for 5 min. Remove the supernatant and repeat the wash step one more time.
to:
Transfer the solution to a conical tube. To isolate the APTMS functionalized SiO2 beads, centrifuge the solution at 10,000 x g for 5 min, then remove the supernatant. Wash the beads by re-dispersing them in 3 mL of fresh methanol. Shake the tube by hand for mixing, but if necessary, improve the dispersion by sonication in a water bath for a few seconds. Centrifuge the beads at 10,000 x g for 5 min. Remove the supernatant and repeat the wash step one more time.
Step 2.1.4 of the Protocol was updated from:
Combine the methanol washed SiO2 beads with 3 mL of dimethyl sulfoxide (DMSO). Shake the mixture by hand, or if necessary sonicate for a few seconds, until the beads are fully dispersed in DMSO. Centrifuge the beads at 10,000 x g for 5 min, then remove the supernatant. Repeat the step to ensure complete solvent exchange from methanol to DMSO.to:
Combine the methanol washed SiO2 beads with 3 mL of dimethyl sulfoxide (DMSO). Shake the mixture by hand, or if necessary sonicate for a few seconds, until the beads are fully dispersed in DMSO. Centrifuge the beads at 10,000 x g for 5 min, then remove the supernatant. Repeat the step to ensure complete solvent exchange from methanol to DMSO.
NOTE: The final suspension contains the APTMS functionalized SiO2 beads dispersed in 4 mL of DMSO.
Step 2.2 of the Protocol was updated from:
Grafting poly(PFPA) to APTES functionalized SiO2 beads
to:
Grafting poly(PFPA) to APTMS functionalized SiO2 beads
Step 2.2.2 of the Protocol was updated from:
Add 1 mL of APTES functionalized SiO2 beads suspended in DMSO (from Step 2.1.4) to the poly(PFPA) solution. React at RT for 1 h with vigorous stirring.
to:
Add 1 mL of APTMS functionalized SiO2 beads suspended in DMSO (from Step 2.1.4) to the poly(PFPA) solution. React at RT for 1 h with vigorous stirring.
Step 3.4 of the Protocol was updated from:
To prepare APTES functionalized SiO2 beads suspended in DMSO, follow the same steps shown in Step 2.1. Transfer 1 mL of the bead suspension into the PEG-substituted poly(PFPA) solution prepared in Step 3.3. Allow the grafting between poly(PFPA) and APTES functionalized SiO2 beads to proceed at RT for 1 h with vigorous stirring.
to:
To prepare APTMS functionalized SiO2 beads suspended in DMSO, follow the same steps shown in Step 2.1. Transfer 1 mL of the bead suspension into the PEG-substituted poly(PFPA) solution prepared in Step 3.3. Allow the grafting between poly(PFPA) and APTMS functionalized SiO2 beads to proceed at RT for 1 h with vigorous stirring.
The first paragraph of the Representative Results was updated from:
A schematic for the preparation of poly(PFPA) grafted SiO2 beads, with or without PEG substitution is shown in Figure 1. To monitor the APTES and poly(PFPA) grafting process, bare SiO2 beads, APTES functionalized SiO2 beads, and poly(PFPA) grafted SiO2 beads are characterized by both DLS (Figure 2) and XPS (Figure 3). IP efficiencies of the beads are determined by Western blotting. Figure 4 shows the Western blotting results for IP using 1% PEG-substituted poly(PFPA) grafted beads, where the beads are incubated with no antibody, a non-specific antibody, or anti-PKR antibody. Figure 5 shows the Western blotting results for IP using 0% PEG-substituted poly(PFPA) grafted beads and 1% PEG-substituted poly(PFPA) grafted beads, both incubated with anti-PKR antibodies.
to:
A schematic for the preparation of poly(PFPA) grafted SiO2 beads, with or without PEG substitution is shown in Figure 1. To monitor the APTMS and poly(PFPA) grafting process, bare SiO2 beads, APTMS functionalized SiO2 beads, and poly(PFPA) grafted SiO2 beads are characterized by both DLS (Figure 2) and XPS (Figure 3). IP efficiencies of the beads are determined by Western blotting. Figure 4 shows the Western blotting results for IP using 1% PEG-substituted poly(PFPA) grafted beads, where the beads are incubated with no antibody, a non-specific antibody, or anti-PKR antibody. Figure 5 shows the Western blotting results for IP using 0% PEG-substituted poly(PFPA) grafted beads and 1% PEG-substituted poly(PFPA) grafted beads, both incubated with anti-PKR antibodies.
Figure 1 was updated from:
Figure 1: Schematic for the preparation of poly(PFPA) grafted SiO2 beads using APTES as a linker molecule. (a) Poly(PFPA) grafted beads. (b) Partially PEG-substituted poly(PFPA) grafted beads.
to:
Figure 1: Schematic for the preparation of poly(PFPA) grafted SiO2 beads using APTMS as a linker molecule. (a) Poly(PFPA) grafted beads. (b) Partially PEG-substituted poly(PFPA) grafted beads.
Figure 2 was updated from:
Figure 2: DLS measurements for (a) bare SiO2 beads (SiO2), (b) APTES functionalized SiO2 beads (APTES-SiO2), and (c) poly(PFPA) grafted SiO2 beads (poly(PFPA)-SiO2), dispersed in DMSO. The Z-average diameter (d) and polydispersity index (PDI) of each sample are reported.
to:
Figure 2: DLS measurements for (a) bare SiO2 beads (SiO2), (b) APTMS functionalized SiO2 beads (APTMS-SiO2), and (c) poly(PFPA) grafted SiO2 beads (poly(PFPA)-SiO2), dispersed in DMSO. The Z-average diameter (d) and polydispersity index (PDI) of each sample are reported.
Figure 3 was updated from:
Figure 3: XPS spectra for bare SiO2 beads (SiO2), APTES functionalized SiO2 beads (APTES-SiO2), and poly(PFPA) grafted SiO2 beads (poly(PFPA)-SiO2). The peaks examined correspond to (a) Si 2p, (b) O 1s, (c) N 1s, and (d) F 1s.
to:
Figure 3: XPS spectra for bare SiO2 beads (SiO2), APTMS functionalized SiO2 beads (APTMS-SiO2), and poly(PFPA) grafted SiO2 beads (poly(PFPA)-SiO2). The peaks examined correspond to (a) Si 2p, (b) O 1s, (c) N 1s, and (d) F 1s.
The first and second paragraphs of the Discussion were updated from:
The synthesis of poly(PFPA) grafted SiO2 beads is illustrated in Figure 1. By employing APTES as a linker molecule, poly(PFPA) brushes covalently grafted to SiO2 substrate can be prepared via a simple two-step process. Although some of the PFP units are sacrificed for the reaction with APTES, a large number of the PFP units are expected to remain available for later reaction with either amino-PEG or antibodies. The PFP groups are known to form low energy surfaces so poly(PFPA) brushes do not solvate well in water28. For IP application, the antibodies need to be immobilized on the poly(PFPA) brushes, and this exchange reaction is done in aqueous buffer solution in order to preserve the activity of the antibodies. As reported in our previous publication, partial substitution of the PFP units with hydrophilic molecules such as amine-functionalized PEG can improve surface hydrophilicity, leading to increased antibody immobilization efficiency18. In this study, partially PEG substituted poly(PFPA) is also prepared, then grafted to the SiO2 surface using the same APTES linker molecule. Overall, the methods illustrated in Figure 1 allow the preparation of poly(PFPA) grafted surfaces with different degrees of PEG substitution. These polymer brushes with tunable surface properties provide an ideal platform for antibody immobilization and subsequent IP application.
The bead preparation process is monitored by both DLS and XPS. The DLS results for various functionalized SiO2 beads in DMSO are summarized in Figure 2. The bare SiO2 beads exhibit hydrodynamic diameter of 666 nm, in agreement with the manufacturer reported bead size (0.676 μm; SD = 0.03 μm). After APTES treatment, the bead diameter increases to 740 nm; and with poly(PFPA) treatment, the bead diameter further increases to 1889 nm. It is important to point out that the polydispersity index (PDI) for the poly(PFPA) grafted beads is rather large (PDI = 0.76), which is indicative of poor quality sample containing large aggregates. Although the DLS curve only shows one nano-sized peak, small amount of aggregates may be present in the suspension. The functionalized SiO2 beads are also examined by XPS to determine surface composition (Figure 3). Following APTES treatment, N 1s peak associated with the amine groups on APTES is detected. And, following poly(PFPA) treatment, F 1s peak associated with the PFP units on the polymer is detected. Together these data show the successful functionalization of the SiO2 surface, first with APTES, then with poly(PFPA).
to:
The synthesis of poly(PFPA) grafted SiO2 beads is illustrated in Figure 1. By employing APTMS as a linker molecule, poly(PFPA) brushes covalently grafted to SiO2 substrate can be prepared via a simple two-step process. Although some of the PFP units are sacrificed for the reaction with APTMS, a large number of the PFP units are expected to remain available for later reaction with either amino-PEG or antibodies. The PFP groups are known to form low energy surfaces so poly(PFPA) brushes do not solvate well in water28. For IP application, the antibodies need to be immobilized on the poly(PFPA) brushes, and this exchange reaction is done in aqueous buffer solution in order to preserve the activity of the antibodies. As reported in our previous publication, partial substitution of the PFP units with hydrophilic molecules such as amine-functionalized PEG can improve surface hydrophilicity, leading to increased antibody immobilization efficiency18. In this study, partially PEG substituted poly(PFPA) is also prepared, then grafted to the SiO2 surface using the same APTMS linker molecule. Overall, the methods illustrated in Figure 1 allow the preparation of poly(PFPA) grafted surfaces with different degrees of PEG substitution. These polymer brushes with tunable surface properties provide an ideal platform for antibody immobilization and subsequent IP application.
The bead preparation process is monitored by both DLS and XPS. The DLS results for various functionalized SiO2 beads in DMSO are summarized in Figure 2. The bare SiO2 beads exhibit hydrodynamic diameter of 666 nm, in agreement with the manufacturer reported bead size (0.676 μm; SD = 0.03 μm). After APTMS treatment, the bead diameter increases to 740 nm; and with poly(PFPA) treatment, the bead diameter further increases to 1889 nm. It is important to point out that the polydispersity index (PDI) for the poly(PFPA) grafted beads is rather large (PDI = 0.76), which is indicative of poor quality sample containing large aggregates. Although the DLS curve only shows one nano-sized peak, small amount of aggregates may be present in the suspension. The functionalized SiO2 beads are also examined by XPS to determine surface composition (Figure 3). Following APTMS treatment, N 1s peak associated with the amine groups on APTMS is detected. And, following poly(PFPA) treatment, F 1s peak associated with the PFP units on the polymer is detected. Together these data show the successful functionalization of the SiO2 surface, first with APTMS, then with poly(PFPA).
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