Oxygen deficiency after myocardial infarction (MI) leads to massive cardiac cell death. Protection of cardiac cells and promotion of cardiac repair are key therapeutic goals. These goals may be achieved by re-introducing oxygen into the infarcted area. Yet current systemic oxygen delivery approaches cannot efficiently diffuse oxygen into the infarcted area that has extremely low blood flow. In this work, we developed a new oxygen delivery system that can be delivered specifically to the infarcted tissue, and continuously release oxygen to protect the cardiac cells. The system was based on a thermosensitive, injectable and fast gelation hydrogel, and oxygen releasing microspheres. The fast gelation hydrogel was used to increase microsphere retention in the heart tissue. The system was able to continuously release oxygen for 4 weeks. The released oxygen significantly increased survival of cardiac cells under the hypoxic condition (1% O2) mimicking that of the infarcted hearts. It also reduced myofibroblast formation under hypoxic condition (1% O2). After implanting into infarcted hearts for 4 weeks, the released oxygen significantly augmented cell survival, decreased macrophage density, reduced collagen deposition and myofibroblast density, and stimulated tissue angiogenesis, leading to a significant increase in cardiac function.

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An efficient surface-enhanced Raman scattering (SERS) method combined with DNA ligation is demonstrated in this proof-of-concept study for the detection of the single-strand DNA associated with BRAF V600E mutation. Gold-coated magnetic nanoparticles with 6-mercaptopyridine-3-carboxylic acid (MPCA) as internal reference attached on the surface (MNP@SiO2@Au-MPCA) and silver nanoparticles with Raman reporter 4-mercaptobenzonic acid (4-MBA) on the surface (Ag@4-MBA) are used as the SERS substrates. Rationally designed DNA probes are conjugated to these two types of nanoparticles, respectively. The single-stranded DNA containing the BRAF V600E mutation is the target analyte, which would act as the substrate for MNP@SiO2@Au-MPCA and Ag@4-MBA to be linked together through ligation. After multiple cycles of DNA ligation, more Ag@4-MBA are brought to the surface of MNP@SiO2@Au-MPCA. The resulting nanoparticles are easily isolated by a magnet rapidly from the mixture and redispersed in aqueous solution for homogeneous SERS measurement. The detection sensitivity is improved by the enhancement of the SERS peaks of 4-MBA between the plasmonic nanoparticles, and the detection quantification is improved by the use of internal reference, MPCA, for signal normalization. The intensity ratio of 4-MBA/MPCA increases linearly in the 1–100 fmol range of the matched DNA (BRAF mutation). Different ratios of matched DNA in the background of a large number of the single-base mismatched DNA (BRAF normal) are used to mimic real samples, and the intensity ratios of 4-MBA/MPCA are linear in the 0.02–1% range of matched DNA/mismatched DNA. The high sensitivity and specificity of the method demonstrate its potential for clinical use.

Alternative metals such as magnesium (Mg) and its alloys have been recently developed for clinical applications such as temporary implants for bone and tissue repair due to their desirable mechanical properties and ability to biodegrade harmlessly in vivo by releasing Mg 2+ , OH − , and H 2 as biodegradation products. The current methods for monitoring in vivo Mg-alloy biodegradation are either invasive and/or costly, complex, or require large equipment and specially trained personnel, thus making real-time and point-of-care monitoring of Mg-alloy implants problematic. Therefore, innovative methods are critically needed. The objective of this research was to develop a novel, thin, and wearable visual H 2 sensor prototype for noninvasive monitoring of in vivo Mg-implant biodegradation in medical research and clinical settings with a fast response time. In this work, we successfully demonstrate such a prototype composed of resazurin and catalytic bimetallic gold-palladium nanoparticles (Au-Pd NPs) incorporated into a thin agarose/alginate hydrogel matrix that rapidly changes color from blue to pink upon exposure to various levels of H 2 at a constant flow rate. The irreversible redox reactions occurring in the sensor involve H 2 , in the presence of Au-Pd NPs, converting resazurin to resorufin. To quantify the sensor color changes, ImageJ software was used to analyze photographs of the sensor taken with a smartphone during H 2 exposure. The sensor concentration range was from pure H 2 down to limits of detection of 6 and 8 μM H 2 (defined via two methods). This range is adequate for the intended application of noninvasively monitoring in vivo Mg-alloy implant biodegradation in animals for medical research and patients in clinical settings.

Self‐healing paints would have the potential benefit of protecting the underlying substrate and extending the coating's service life. As a step toward those types of coatings, this work examines layer‐by‐layer films of branched poly(ethylene imine)/poly(acrylic acid) with the inclusion of various types of latex particles with different Tg and different compositions. Due to high mobility of the polyelectrolyte chains when plasticized with water, water enabled self‐healing of these films is demonstrated, as well as steam enabled self‐healing. The films with various latex particles show different swelling ratios, surface hydrophilicity, as well as varying ability to self‐heal scratches. This self‐healing property is studied as a function of temperature. Also, the mechanical properties such as hardness and modulus of the films are measured.