This work establishes a correlation between the selectivity of hydrogen-bonding interactions and the functionality of micelle-containing layer-by-layer (LbL) assemblies. Specifically, we explore LbL films formed by assembly of poly(methacrylic acid) (PMAA) and upper critical solution temperature block copolymer micelles (UCSTMs) composed of poly(acrylamide-co-acrylonitrile) P(AAm-co-AN) cores and polyvinylpyrrolidone (PVP) coronae. UCSTMs had a hydrated diameter of ∼380 nm with a transition temperature between 45 and 50 °C, regardless of solution pH. Importantly, micelles were able to hydrogen-bond with PMAA, with the critical interaction pH being temperature dependent. To better understand the thermodynamic nature of these interactions, in depth studies using isothermal titration calorimetry (ITC) were conducted. ITC reveals opposite signs of enthalpies for binding of PMAA with micellar coronae vs. with the cores. Moreover, ITC indicates that pH directs the interactions of PMAA with micelles, selectively enabling binding with the micellar corona at pH 4 or with both the corona and the core at pH 3. We then explore UCSTM/PMAA LbL assemblies and show that the two distinct modes of PMAA interaction with the micelles (i.e. whether or not PMAA binds with the core) had significant effects on the film composition, structure, and functionality. Consistent with PMAA hydrogen bonding with the P(AAm-co-AN) micellar cores, a significantly higher fraction of PMAA was found within the films assembled at pH 3 compared to pH 4 by both spectroscopic ellipsometry and neutron reflectometry. Selective interaction of PMAA with PVP coronae of the assembled micelles, achieved by the emergence of partial ionization of PMAA at pH 4 was critical for preserving film functionality demonstrated as temperature-controlled swelling and release of a model small molecule, pyrene. The work done here can be applied to a multitude of assembled polymer systems in order to predict suppression/retention of their stimuli-responsive behavior.

The vascular smooth muscle is vital for regulating blood pressure and maintaining cardiovascular health, and the resident smooth muscle cells (SMCs) in blood vessel walls rely on specific mechanical and biochemical signals to carry out these functions. Any slight change in their surrounding environment causes swift changes in their phenotype and secretory profile, leading to changes in the structure and functionality of vessel walls that cause pathological conditions. To adequately treat vascular diseases, it is essential to understand how SMCs crosstalk with their surrounding extracellular matrix (ECM). Here, we summarize in vivo and traditional in vitro studies of pathological vessel wall remodeling due to the SMC phenotype and, conversely, the SMC behavior in response to key ECM properties. We then analyze how three-dimensional tissue engineering approaches provide opportunities to model SMCs’ response to specific stimuli in the human body. Additionally, we review how applying biomechanical forces and biochemical stimulation, such as pulsatile fluid flow and secreted factors from other cell types, allows us to study disease mechanisms. Overall, we propose that in vitro tissue engineering of human vascular smooth muscle can facilitate a better understanding of relevant cardiovascular diseases using high throughput experiments, thus potentially leading to therapeutics or treatments to be tested in the future.

Arterial diseases alter blood vessel function through complex mechanisms, requiring microphysiological systems that mimic human arteries. We established an artery‐on‐chip (ARTOC) using vascular derivatives of human induced pluripotent stem cells (iPSCs) cultured with pulsatile flow on an electrospun fibrin hydrogel. ARTOCs possessed mature, multilayered smooth muscle expressing robust extracellular matrix and contractile proteins, exhibiting stimuli‐induced contractility and achieving material properties comparable to those of native arteries. Using real‐time monitoring of circumferential strain and luminal pressure to inform computational fluid dynamics modeling, we successfully tuned biomechanical cues to promote the function of both endothelial and smooth muscle cells simultaneously in the ARTOC. Multiplexed protein and transcriptomic expression analysis of ARTOCs revealed a dynamic response to pulsatile flow over time. For disease modeling, we used iPSCs from a polycythemia patient, finding aberrant cytoskeletal protein expression and increased vessel wall stiffness in diseased ARTOCs compared to controls. We then characterized a novel isogenic disease model using iPSCs CRISPR‐edited with the LMNA Hutchinson‐Guilford Progeria Syndrome mutation. LMNA ^HGPS ARTOCs showed excessive extracellular matrix accumulation, medial layer loss, premature senescence, and reduced tissue elasticity. The tunable material‐based ARTOC platform accurately models healthy and diseased arteries, representing a significant step toward translational research.

The spectroscopic method based on surface-enhanced Raman spectroscopy (SERS) technique combined with chemometric methods was developed for simple, cost-effective, and efficient analysis of chlorpyrifos (CPF) and aldicarb (ALD) pesticide residues in animal feed. Animal feeds free from the pesticides were spiked at different concentrations of CPF (0-20 mg/kg) and aldicarb (0-100 µg/kg). Gold nanoparticles were mixed with sample extract for SERS measurement. A significant spectral difference induced by the presence and different level of CPF and ALD concentration in animal feed was observed between the pesticide spiking groups. Different chemometric models applied on training datasets showed excellent classification rates (100 percent) while the models on external validation dataset exhibited lower correct classification rates (50.0-76.7 percent) with no false-negative error. The selected chemometric models for CPF and ALD quantification also showed a high predictive ability and performance. The developed models displayed no statistical significant difference between model predicted and reference values in the external validation dataset (p < 0.01). The study results indicate that the SERS spectroscopic method could be an effective and efficient analytical tool for pesticide analysis in highly complex animal feed matrices for screening at a point of sampling to improve food and feed safety. https://doi.org/10.21423/jrs-v08lee