Enabling the Selective Detection of Endocrine-Disrupting Chemicals via Molecularly Surface-Imprinted "Coffee Rings".

Molecularly imprinted polymers (MIPs) represent an intriguing class of synthetic materials that can selectively recognize and bind chemical or biological molecules in a variety of value-added applications in sensors, catalysis, drug delivery, antibodies, and receptors. In this context, many advanced methods of implementing functional MIP materials have been actively studied. Herein, we report a robust strategy to produce highly ordered arrays of surface-imprinted polymer patterns with unprecedented regularity for MIP-based sensor platform, which involves the controlled evaporative self-assembly process of MIP precursor solution in a confined geometry consisting of a spherical lens on a flat Si substrate (i.e., sphere-on-flat geometry) to synergistically utilize the "coffee-ring" effect and repetitive stick-slip motions of the three-phase contact line simply by solvent evaporation. Highly ordered arrays of the ring-patterned MIP films are then polymerized under UV irradiation to achieve semi-interpenetrating polymer networks. The extraction of templated target molecules from the surface-imprinted ring-patterned MIP films leaves behind copious cavities for the recognizable specific "memory sites" to efficiently detect small molecules. As a result, the elaborated surface structuring effect, sensitivity, and specific selectivity of the coffee-ring-based MIP sensors are scrutinized by capitalizing on an endocrine-disrupting chemical, 2,4-dichlorophenoxyacetic acid (2,4-D), as an example. Clearly, the evaporative self-assembly of nonvolatile solutes in a confined geometry renders the creation of familiar yet ordered coffee-ring-like patterns for a wide range of applications, including sensors, scaffolds for cell motility, templates, substrates for neuron guidance, etc., thereby dispensing with the need of multistep lithography techniques and external fields.

Biomimetic 3D Tissue Models for Advanced High-Throughput Drug Screening.

Most current drug screening assays used to identify new drug candidates are 2D cell-based systems, even though such in vitro assays do not adequately re-create the in vivo complexity of 3D tissues. Inadequate representation of the human tissue environment during a preclinical test can result in inaccurate predictions of compound effects on overall tissue functionality. Screening for compound efficacy by focusing on a single pathway or protein target, coupled with difficulties in maintaining long-term 2D monolayers, can serve to exacerbate these issues when using such simplistic model systems for physiological drug screening applications. Numerous studies have shown that cell responses to drugs in 3D culture are improved from those in 2D, with respect to modeling in vivo tissue functionality, which highlights the advantages of using 3D-based models for preclinical drug screens. In this review, we discuss the development of microengineered 3D tissue models that accurately mimic the physiological properties of native tissue samples and highlight the advantages of using such 3D microtissue models over conventional cell-based assays for future drug screening applications. We also discuss biomimetic 3D environments, based on engineered tissues as potential preclinical models for the development of more predictive drug screening assays for specific disease models.