Ramiro Marroquin-Garcia

Bacterial endospores are a major challenge in food safety due to their high resistance and potential to cause spoilage and foodborne illness. Current detection methods can be labor-intensive and require specialized instrumentation. A low-cost, label-free thermal sensing platform for indirect detection of Bacillus cereus endospores using molecularly imprinted polymers (MIPs) targeting dipicolinic acid (DPA), a spore biomarker, was developed. The MIPs were synthesized by free-radical bulk polymerization, characterized by rebinding assays, and evaluated using the Heat Transfer Method (HTM). At 100 μM DPA, the MIPs exhibited an imprinting factor (IF) of 2.62 ± 0.18 (n = 3), demonstrating preferential DPA binding. Sensor performance was evaluated using aqueous DPA, structural analogues, and a complex food matrix. HTM measurements produced concentration-dependent responses, with limits of detection of 0.20 ± 0.15 μM in aqueous DPA solutions and 0.060 ± 0.0098 μM in unpretreated, spiked ultrahigh-temperature (UHT) milk. Terbium(III) fluorescence independently supported DPA retention by the MIPs. Real-time assays with germinated B. cereus suspensions at 105 colony-forming units (CFU) mL–1 enabled proof-of-concept monitoring of biologically released DPA under laboratory conditions. These findings highlight the potential of combining DPA-imprinted polymers with HTM for real-time and label-free indirect endospore detection.

Timely identification of pathogens within the food production chain is crucial to prevent spoilage and reduce the substantial economic burden associated with crop loss. Botrytis cinerea is the causative agent of gray mold disease, which affects important crops such as tomatoes. In this study, we introduce a sensing platform for real-time monitoring of this fungus. The sensor consists of a polymeric receptor imprinted with the physical and chemical characteristics of the fungus’s spores, enabling identification. Detection is achieved using a thermal transducer, which offers a reproducible concentration-dependent signal toward the analyte. The sensor was tested for specificity with other spores (Ampelomyces quisqualis, Fusarium oxysporum, and Akanthomyces muscarius), with a significantly higher response intensity for the targeted microorganism. The sensor’s practical applicability was evaluated using B. cinerea-containing water collected from a greenhouse dedicated to tomato cultivation. These results highlight the platform’s potential as a routine monitoring tool for this plant pathogen.

Xylazine adulterated Fentanyl is considered one of the deadliest drug threats ever faced in the United States. However, due to the complexity of the illegal drug supply, xylazine detection in the frame of drug-checking (harm reduction) remains an unsolved challenge, one which has cost numerous lives across North America. In this work, we present two sensor platforms for detecting xylazine in drug-checking applications. Both platforms are based on molecularly imprinted polymers (MIPs) using vinyl phosphonic acid as the main monomer. By combining the MIPs with thermometric and colorimetric readouts, we achieved xylazine detection in a wide concentration range, relevant in real-world scenarios. First, the heat-transfer method (HTM) allowed xylazine detection in the low concentration range within 15 min per concentration, with a limit of detection (LoD) of 16.5 ng/mL (75 nM). Second, a dye displacement assay employing methylene blue provided rapid ( 76 μg/mL-five times lower than the average concentration reported for street samples. Additionally, the colorimetric sensor exhibited potential for detecting various unwanted xylazine analogues, which could potentially act as fentanyl adulterants in the future. Most importantly, the colorimetric sensor consistently detected xylazine in a highly complex, street-like fentanyl sample containing five common interferents. The synergy of the proposed sensors offers a promising alternative for centralized and on-site xylazine screening in harm reduction settings.

The creation of biodegradable and biocompatible shape memory polymers amenable to biofabrication techniques remains a challenge. The ability to create shape-changing biodegradable objects that are triggered at body temperature opens up possibilities in tissue engineering, minimally invasive surgery, and actuating bioimplants. Merging Digital Light Processing (DLP) printing with shape memory polymers brings us closer to new smart biomedical outcomes. Previously, we developed a poly(caprolactone-co-trimethylenecarbonate) urethane acrylate resin for the DLP fabrication of biodegradable 3D objects. In further studies, we observed that some of these resins possessed shape memory properties, triggered by body temperature (37 °C). In this subsequent study, we explored the shape memory properties and tunability of this resin family via changes in copolymer composition, molecular weight, and identity of the acrylate end-capping unit. We found that we could create a library of shape memory resins, amenable to DLP printing, which allowed the creation of shape-actuating structures with some tunability over the speed of shape memory and mechanical properties. We observed that increased mole fraction of caprolactone in the copolymer and increased molecular weight of the polymer led to a decrease in speed of the shape memory switch. Furthermore, we observed a trade-off between the composition and the end-capping moiety on the mechanical properties of the polymers. These polymeric resins were able to be processed into shapes that were able to perform work, including the release of cargo and grabbing/lifting of an object. This platform now provides a way to tune the speed and mechanical properties of a shape memory DLP object created from common and scalable polymerization techniques. This work ultimately provides a new platform to develop customizable and biodegradable devices capable of actuating and delivery devices for numerous biomedical applications.

Introducing the reverse micelle formation during polymerization, and thus avoiding the catalyst support, aggregated single crystals of ultra‐high molecular weight isotactic polypropylene having spherical morphology are obtained. The ease in flowability of the spherical nascent morphology, having a low‐entangled state in the non‐crystalline region of the single crystals in the semi‐crystalline polymer, allows the sintering of the nascent polymer in the solid state without melting. Thus maintains a low‐entangled state, and facilitates the translation of macroscopic forces to macromolecular length scale, without melting, leading to the formation of uniaxially drawn objects having unprecedented properties that can be used in the development of one component, high‐performance, easy‐to‐recycle composites. Thus having the potential of replacing difficult‐to‐recycle hybrid composites.

To exploit the usability of Digital Light Processing (DLP) in regenerative medicine, biodegradable, mechanically customizable and well-defined polyester urethane acrylate resins were synthesized based on poly(caprolactone-co-trimethlenecarbonate). By controlling the monomer ratio, the resultant fabricated constructs showed tunable mechanical properties, degradation and attached hMSC morphologies.