The persistence of drug resistant cell populations following chemotherapeutic treatment is a significant challenge in the clinical management of cancer. Resistant subpopulations arise via both cell intrinsic and extrinsic mechanisms. Extrinsic factors in the microenvironment, including neighboring cells, glycosaminoglycans, and fibrous proteins impact therapy response. Elevated levels of extracellular fibrous proteins are associated with tumor progression and cause the surrounding tissue to stiffen through changes in structure and composition of the extracellular matrix (ECM). We sought to determine how this progressively stiffening microenvironment affects the sensitivity of breast cancer cells to chemotherapeutic treatment. MDA-MB-231 triple negative breast carcinoma cells cultured in a 3D alginate-based hydrogel system displayed a stiffness-dependent response to the chemotherapeutic doxorubicin. MCF7 breast carcinoma cells cultured in the same conditions did not exhibit this stiffness-dependent resistance to the drug. This differential therapeutic response was coordinated with nuclear translocation of YAP, a marker of mesenchymal differentiation. The stiffness-dependent response was lost when cells were transferred from 3D to monolayer cultures, suggesting that endpoint ECM conditions largely govern the response to doxorubicin. To further examine this response, we utilized a platform capable of dynamic ECM stiffness modulation to allow for a change in matrix stiffness over time. We found that MDA-MB-231 cells have a stiffness-dependent resistance to doxorubicin and that duration of exposure to ECM stiffness is sufficient to modulate this response. These results indicate the need for additional tools to integrate mechanical stiffness with therapeutic response and inform decisions for more effective use of chemotherapeutics in the clinic.

Hydrogels have been influential in the development of controlled release systems for a wide variety of therapeutic agents. These materials are attractive as carriers for transmucosal and intracellular drug delivery because of their inherent biocompatibility, tunable physicochemical properties, basic synthesis, and ability to be physiologically responsive. Due to their hydrophilic nature, hydrogel-based carrier systems are not always the best systems for delivery of small molecular weight, hydrophobic therapeutic agents. In this work, versatile hydrogel-based carriers composed of copolymers of methyl methacrylate (MMA) and acrylic acid (AA) were designed and synthesized to create formulations for oral delivery of small molecular weight therapeutic agents. Through practical material selection and careful design of copolymer composition and molecular architecture, we engineered systems capable of responding to physiological changes, with tunable physicochemical properties that are optimized to load, protect, and deliver their payloads to their intended site of action. The synthesized carriers’ ability to respond to changes in pH, to load and release small molecular weight drugs, and biocompatibility were investigated. Our results suggest these hydrophilic networks have great potential for controlled delivery of small-molecular weight, hydrophobic and hydrophilic agents.

pH responsive hydrogels are ideal platforms for numerous therapeutic delivery applications, including oral delivery, as they are capable of overcoming the many barriers that must be considered when creating an effective drug delivery system. Understanding of the innate hydrogel network structure and its swelling behavior at environmentally relevant conditions is vital for designing hydrogel network capable of effective controlled drug release. Herein, we explored how to expand traditional techniques of swelling and pore characterization to gain better insight into the performance of anionic microparticles composed of the poly(methyl methacrylate‐co‐acrylic acid) with varying molar percentage of 10, 20, and 30 mol% of MMA, for controlled release of low‐molecular‐weight drugs. By evaluating these carrier systems at environmental conditions, we can observe changes in swelling and pore size of the anionic hydrogel networks as a function of MMA, which was then correlated with the release profiles of the small‐molecular‐weight drug sodium nitrate. With the correlation of the swelling behavior of the networks and the release profiles, we demonstrated how the expansion of swelling parameters at relevant pH values provides further incite for evaluating for the optimal blend for controlled release. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48767.

Despite advancements in tissue engineering, the methods used to generate three-dimensional (3D) in vitro models for rapid screening and characterization studies remain time and labor intensive. Bioprinting offers an opportunity to offset these limitations by providing a scalable, high-throughput method with precise control over biomaterial scaffold and cellular deposition. However, the process of formulating bioinks can be complex in terms of balancing the mechanical integrity of a bioscaffold and viability of cells. One key factor, especially in alginate-based bioinks, is the rate of bioscaffold dissolution. It must allow cells to replace the bioscaffold with extracellular matrix (ECM), yet remain durable during extended tissue culture. This study uses a Design of Experiments (DoE) approach to understand the dependencies of multiple variables involved in the formulation and processing of an alginate-based bioink. The focus of the DoE was to understand the effects of hydrogel composition on bioink durability while maintaining cell viability. Three ingredients were varied in all: alginate, nanocellulose, and fibrinogen. Their effects on the bioink were then measured with respect to extrudability, strength, and stiffness as determined by dynamic mechanical analysis (DMA). The DoE demonstrated that mechanical integrity increased with increasing alginate concentration. In contrast, fibrinogen and nanofibril concentration had no statistically significant effect. The optimized ink containing fibroblasts was printable using multiple nozzle sizes while also supporting fibroblast cell viability. DMA characterization further showed that the composition of the cell culture medium did not modulate the degradation rate of the hydrogel. Ultimately, the study outlines a methodology for formulating a bioink that will result in robust bioscaffolds for in vitro model development.

The long-term exposure of low levels of the fungicide, 2-phenylphenol (2-PP), to the environment presents a hazard to human and aquatic health. The cost and difficulty in large-scale production limit the use of existing sensors to detect 2-PP for applications such as personal protection and persistent environmental monitoring of large areas. While advances have been made in using whole cells as biosensors for specific chemical detection, a whole-cell biosensor system with robust biocontainment for field deployment and a strong visual reporter for readouts in the deployed environment has yet to be realized. Here, engineered biosensors in an encapsulated and deployable system (eBEADS) were created to demonstrate a portable, no-power living sensor for detection of 2-PP in the environment. A whole-cell living sensor to detect 2-PP was developed in Escherichia coli by utilizing the 2-PP degradation pathway with an agenetic amplification circuit to produce a visual colorimetric output. To enable field deployment, a physical biocontainment system comprising polyacrylamide alginate beads was designed to encapsulate sensor strains, support long-term viability without supplemental nutrients, and allow permeability of the target analyte. Integration of materials and sensing strains has led to the development of a potential deployable end-to-end living sensor that, with the addition of an amplification circuit, has up to a 66-fold increase in β-galactosidase reporter output over non-amplified strains, responding to as little as 1 μM 2-PP while unencapsulated and 10 μM 2-PP while encapsulated. eBEADS enable sensitive and specific in-field detection of environmental perturbations and chemical threats without electronics.