Multidimensional Anisotropic Architectures on Polymeric Microparticles

Abstract

microfluidics, [9] centrifugation, [10] electrohydrodynamics, [11] and two-photon lithography [6] have been developed to fabricate microparticles with selected physical traits. However, the combination of all of these physical traits and further customization of properties in a single microparticle to augment the functionality, are hindered by the limitations to combining complementary physical anisotropies. In parallel, research has also focused on chemical anisotropy. Extended anisotropy can be implemented with the addition of subdivisions during fabrication, albeit limited by the process, or with posterior functionalization which may be obstructed by the stochastic nature of suspended microparticles in a reactive solution or limited by the available orthogonal chemical reaction sites present on the surface of the microparticles. [12] Imaginative solutions have been used to fabricate multiple subdivided microparticles or chips, offering an attractive approach in the encoding [4,5] and anticounterfeiting [13] fields, yet their main utilization has centered on biomedical and bioengineering. [9,14] Nevertheless, the combination of different customized properties to increase functionality in a single microparticle is limited by the availability of reactive pathways that would otherwise allow the incorporation of complementary chemical anisotropies. Consolidation of these technologies has advanced considerably in the microparticle field, yet the constant trade-off between physical anisotropies, chemical anisotropies and their combination limits the library of possible customized microparticles, a problem that is aggravated by miniaturization. In this work, we aim to remove constraints placed by entangled physical and chemical anisotropies to fabricate polymeric microparticles with customized traits. We achieve this by combining physical attributes and surface chemical functionalization to obtain SU-8 microparticles with specific anisotropic signatures at coordinates established in selected dimensions or domains, [3,15] which collectively define the multidimensional anisotropic space. To do so, we exploit standard SU-8 photolithography to invest the required physical anisotropies on the resulting wafer-bound microparticles. We then incorporate chemical anisotropy with soft lithography on the top, bottom or both surfaces of the microparticles with multiple patterned molecular inks. This collective approach guarantees a highthroughput and low polydispersity fabrication protocol without the need for excessively specialized facilities. Furthermore, the Next generation life science technologies will require the integration of building blocks with tunable physical and chemical architectures at the microscale. A central issue is to govern the multidimensional anisotropic space that defines these microparticle attributes. However, this control is limited to one or few dimensions due to profound fabrication tradeoffs, a problem that is exacerbated by miniaturization. Here, a vast number of anisotropic dimensions are integrate...