Swelling behavior of nanoscale, shape- and size-specific, hydrogel particles fabricated using imprint lithography
Swelling behavior of nanoscale, shape- and size-specific, hydrogel particles fabricated using imprint lithography
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DOI：
10.1039/c0sm01185a
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发表时间：
2011-01-01
期刊：
影响因子：
3.4
通讯作者：
Roy, Krishnendu
中科院分区：
文献类型：
--
作者：
Caldorera-Moore, Mary;Kang, Min Kyoo;Roy, Krishnendu
最近已经报道了许多基于水凝胶的微米级和纳米级药物载体，包括自上而下制造的特定尺寸和形状的高度单分散的纳米颗粒。这种方法的一个关键问题是，纳米颗粒的体内溶胀是否会显著改变其几何形状，使其无法实现控制尺寸或形状的潜在益处。关于纳米级水凝胶结构的溶胀行为的实验表征报道很少，目前的理论认识主要基于散装水凝胶系统。使用原子力显微镜（AFM）和环境扫描电子显微镜（ESEM）胶囊，我们已经表征了不同尺寸和纵横比的纳米印迹水凝胶颗粒的溶胀行为。我们的研究结果表明，尺寸依赖的溶胀，这可以归因于作为制造的颗粒的基板约束的效果，当颗粒仍然附着在压印基板。基于最近发展的场论和非线性有限元方法进行了数值模拟，以说明特定几何形状的基板支撑的水凝胶颗粒的溶胀和干燥行为的约束效应，并与实验测量密切比较。此外，我们提出了一个理论模型，预测无约束的亚微米水凝胶颗粒的尺寸依赖性的溶胀行为，由于表面张力的影响。实验和理论结果都表明，水凝胶溶胀不会显著改变本研究中使用的高度交联的纳米级水凝胶颗粒的形状和尺寸。
Recently a number of hydrogel-based micro-and nanoscale drug carriers have been reported including top down fabricated, highly monodisperse nanoparticles of specific sizes and shapes. One critical question on such approaches is whether in vivo swelling of the nanoparticles could considerably alter their geometry to a point where the potential benefit of controlling size or shape could not be realized. Little has been reported on experimental characterization of the swelling behavior of nanoscale hydrogel structures, and current theoretical understanding is largely based on bulk hydrogel systems. Using atomic force microscopy (AFM) and environmental scanning electron microscopy (ESEM) capsules, we have characterized the swelling behavior of nano-imprinted hydrogel particles of different sizes and aspect ratios. Our results indicate a size-dependent swelling which can be attributed to the effect of substrate constraint of as-fabricated particles, when the particles are still attached to the imprinting substrate. Numerical simulations based on a recently developed field theory and a nonlinear finite element method were conducted to illustrate the constraint effect on swelling and drying behavior of substrate-supported hydrogel particles of specific geometries, and compared closely with experimental measurements. Further, we present a theoretical model that predicts the size-dependent swelling behavior for unconstrained sub-micron hydrogel particles due to the effect of surface tension. Both experimental and theoretical results suggest that hydrogel swelling does not significantly alter the shape and size of highly crosslinked nanoscale hydrogel particles used in the present study.