Results
Preliminary experiments were conducted to calibrate the instrumentation used
in this study and to determine the amount of particles needed for reliable detection.
We used dilutions prepared from purchased silicon dioxide (SiO2) standards
(Postnova Analytics) with a known particle size, 70 nm, and a starting concentration of 25 mg/ml of particles suspended in aqueous surfactant. With the available light scattering detector, reliable quantification of the standard could be obtained with as few as 7 × 1010 particles per injected sample, which is equivalent to 25 μg of particle mass. Based on these data, our subsequent experimental work used tissue samples containing 1–2 mg of particles. Using particle aliquots greater than 40 times the limit of detection enabled robust quantification in the experiments to develop nanoparticle recovery protocols.
To allow comparison of the SdFFF results to established techniques, we performed fluorescence microscopy and TEM on particle-treated cell culture samples treated with rhodamine-labeled SiO2 particles and prepared by enzyme digestion for SdFFF analysis. Figure 1A shows the starting 70-nm rhodamine labeled particles in aqueous surfactant visualized using TEM. The TEM confirms that the manufacturer’s size is correct. Figure 1B demonstrates the interaction of 70-nm rhodamine labeled particles with Human Aortic Endothelial Cells (HAECs). This image shows localization of the nanoparticles to the cells and formation of micron sized aggregates which are visible by light microscopy. During the first step of our SdFFF particle analysis procedure, the cells are collected, lysed and treated with Proteinase K to digest proteins. Figure 1C shows a microscopy image of the cell debris and aggregated fluorescent particles at this stage of the isolation process. A sample after the final cleanup prior to FFF analysis was analyzed via fluorescence microscopy, however the particles were well dispersed, and not visible, by lightmicroscopy (data not shown). Figure 1D shows a TEM image of these particles after final cleanup and dried onto a grid. The particles are aggregated and coated by residual organic material. SdFFF separation of the particles form soluble components yields the monodispersed particles can be seen by TEM (data not shown) [19]. These rhodamine-labeled SiO2 particles have the same manufacturer, and nominal size and surface functionalization as the unlabeled SiO2 particles usedfor the SdFFF experiments.
ผลลัพธ์การทดลองเบื้องต้นได้ดำเนินการปรับเทียบเครื่องมือวัดที่ใช้ในการศึกษานี้ และ เพื่อกำหนดจำนวนของอนุภาคที่จำเป็นสำหรับตรวจสอบความน่าเชื่อถือเราใช้ dilutions เตรียมจากมาตรฐานซื้อซิลิกอนไดออกไซด์ (SiO2)(วิเคราะห์ postnova) มีขนาดอนุภาคที่รู้จัก 70 nm และความเข้มข้นเริ่มต้นของ 25 mg/ml ของอนุภาคที่ถูกระงับใน surfactant อควี ด้วยเครื่องตรวจจับแสง scattering มี นับความน่าเชื่อถือของมาตรฐานสามารถดึง มีน้อย 7 × 1010 อนุภาคต่ออย่างฉีด ซึ่งจะเท่ากับ 25 μg ของอนุภาคมวล ตามข้อมูลเหล่านี้ งานทดลองต่อมาใช้ตัวอย่างเนื้อเยื่อที่ประกอบด้วย 1 – 2 มิลลิกรัมของอนุภาค ใช้มากกว่า 40 ครั้งจำนวนตรวจพบอนุภาค aliquots เปิดนับประสิทธิภาพในการทดลองพัฒนา nanoparticle กู้คืนโพรโทคอลTo allow comparison of the SdFFF results to established techniques, we performed fluorescence microscopy and TEM on particle-treated cell culture samples treated with rhodamine-labeled SiO2 particles and prepared by enzyme digestion for SdFFF analysis. Figure 1A shows the starting 70-nm rhodamine labeled particles in aqueous surfactant visualized using TEM. The TEM confirms that the manufacturer’s size is correct. Figure 1B demonstrates the interaction of 70-nm rhodamine labeled particles with Human Aortic Endothelial Cells (HAECs). This image shows localization of the nanoparticles to the cells and formation of micron sized aggregates which are visible by light microscopy. During the first step of our SdFFF particle analysis procedure, the cells are collected, lysed and treated with Proteinase K to digest proteins. Figure 1C shows a microscopy image of the cell debris and aggregated fluorescent particles at this stage of the isolation process. A sample after the final cleanup prior to FFF analysis was analyzed via fluorescence microscopy, however the particles were well dispersed, and not visible, by lightmicroscopy (data not shown). Figure 1D shows a TEM image of these particles after final cleanup and dried onto a grid. The particles are aggregated and coated by residual organic material. SdFFF separation of the particles form soluble components yields the monodispersed particles can be seen by TEM (data not shown) [19]. These rhodamine-labeled SiO2 particles have the same manufacturer, and nominal size and surface functionalization as the unlabeled SiO2 particles usedfor the SdFFF experiments.
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