Cho Kyunghee, Fasoli Jennifer B, Yoshimatsu Keiichi, Shea Kenneth J, Corn Robert M
Department of Chemistry, University of California-Irvine, Irvine, California 92697, United States.
Anal Chem. 2015;87(9):4973-9. doi: 10.1021/acs.analchem.5b00776. Epub 2015 Apr 14.
This paper describes how changes in the refractive index of single hydrogel nanoparticles (HNPs) detected with near-infrared surface plasmon resonance microscopy (SPRM) can be used to monitor the uptake of therapeutic compounds for potential drug delivery applications. As a first example, SPRM is used to measure the specific uptake of the bioactive peptide melittin into N-isopropylacrylamide (NIPAm)-based HNPs. Point diffraction patterns in sequential real-time SPRM differential reflectivity images are counted to create digital adsorption binding curves of single 220 nm HNPs from picomolar nanoparticle solutions onto hydrophobic alkanethiol-modified gold surfaces. For each digital adsorption binding curve, the average single nanoparticle SPRM reflectivity response, ⟨Δ%RNP⟩, was measured. The value of ⟨Δ%RNP⟩ increased linearly from 1.04 ± 0.04 to 2.10 ± 0.10% when the melittin concentration in the HNP solution varied from zero to 2.5 μM. No change in the average HNP size in the presence of melittin is observed with dynamic light scattering measurements, and no increase in ⟨Δ%RNP⟩ is observed in the presence of either FLAG octapeptide or bovine serum albumin. Additional bulk fluorescence measurements of melittin uptake into HNPs are used to estimate that a 1% increase in ⟨Δ%RNP⟩ observed in SPRM corresponds to the incorporation of approximately 65000 molecules into each 220 nm HNP, corresponding to roughly 4% of its volume. The lowest detected amount of melittin loading into the 220 nm HNPs was an increase in ⟨Δ%RNP⟩ of 0.15%, corresponding to the absorption of 10000 molecules.
本文描述了如何利用近红外表面等离子体共振显微镜（SPRM）检测单个水凝胶纳米颗粒（HNP）的折射率变化，来监测治疗性化合物的摄取情况，以用于潜在的药物递送应用。作为第一个例子，SPRM用于测量生物活性肽蜂毒肽对基于N-异丙基丙烯酰胺（NIPAm）的HNP的特异性摄取。对连续实时SPRM差分反射率图像中的点衍射图案进行计数，以创建单个220 nm HNP从皮摩尔纳米颗粒溶液到疏水链烷硫醇修饰金表面的数字吸附结合曲线。对于每条数字吸附结合曲线，测量平均单个纳米颗粒的SPRM反射率响应⟨Δ%RNP⟩。当HNP溶液中蜂毒肽浓度从零变化到2.5 μM时，⟨Δ%RNP⟩的值从1.04±0.04线性增加到2.10±0.10%。动态光散射测量未观察到蜂毒肽存在时HNP平均尺寸的变化，在存在FLAG八肽或牛血清白蛋白时也未观察到⟨Δ%RNP⟩的增加。对蜂毒肽摄取到HNP中的额外体相荧光测量用于估计，在SPRM中观察到的⟨Δ%RNP⟩增加1%对应于每个220 nm HNP中约65000个分子的掺入，约占其体积的4%。检测到的220 nm HNP中蜂毒肽负载的最低量是⟨Δ%RNP⟩增加0.15%，对应于10000个分子的吸收。
