Real-Time Fluorescence Tracking of Protoporphyrin Incorporated Thermosensitive Hydrogel and Its Drug Release <i>in Vivo</i>

Fluorescence imaging <i>in vivo</i> will pave an important way for the evaluation of biomaterials. The major advantage of fluorescence imaging compared to other imaging modalities is the possibility of tracking two or more fluorescence probes simultaneously with multispectral fluorescence imaging. It is essential to elucidate the location, erosion, drug release and resection of implanted biomaterials <i>in vivo</i>. Herein, a thermosensitive hydrogel with a protoporphyrin core based on a PEG and PCL copolymer (PCL–PEG–PPOR–PEG–PCL) was synthesized by ring-opening polymerization using protoporphyrin as a fluorescence tag. The optical properties of the hydrogel were investigated by UV–vis and fluorescence spectroscopy <i>in vitro</i> and by fluorescence imaging system <i>in vivo</i>. The hydrogel erosion and drug delivery <i>in vivo</i> were monitored and tracked by multispectral fluorescence imaging system in nude mice. The results show that the thermosensitive hydrogel exhibits fluorescence and injectability <i>in vivo</i> with good biocompatibility. Through the modality of fluorescence imaging, the status of the hydrogel is reflected <i>in situ</i> <i>in vivo</i> including its location and erosion. Multispectral analysis separates the autofluorescence signals from the specific label and provides the ability to locate the drug and carrier. The protoporphyrin incorporated thermosensitive hydrogel can be a potential visiable biomedical implant for tissue repair or drug delivery

Incorporation of Poly(ethylene 2,5-furanoate) into Poly(butylene adipate-<i>co</i>-terephthalate) toward Sustainable Food Packaging Films with Enhanced Strength and Barrier Properties

The development of environment-friendly biodegradable materials has aroused widespread attention and interest. Herein, kilogram-scale poly(ethylene 2,5-furanoate) (PEF) was synthesized and incorporated into poly(butylene adipate-co-terephthalate) (PBAT) via melt-compounding. Then, the PBAT/PEF blend films were prepared by the extrusion blowing method. The results showed that PEF could greatly improve the tensile performance and tear resistance of PBAT/PEF blend films. The superior mechanical properties were achieved in PBAT/PEF10 blend films with a tensile strength of 44.3 ± 2.9 MPa and an elongation at break of 900.5 ± 21.9%. Besides, the transmittance of oxygen (O2), carbon dioxide (CO2), and water vapor sharply reduced by 78.8, 74, and 48.3% in comparison with those of a pure PBAT film, respectively. The inherent barrier characteristic of PEF and the enhanced bonding between PBAT and PEF contributed to the excellent gas and water vapor barrier performance. Furthermore, PBAT/PEF blend films were used for the fruit preservation tests. After a 15 day preservation, the freshness of fruits covered with PBAT/PEF films was well kept, showing great potentialin food packing applications

High-Barrier Poly(butylene succinate-<i>co</i>-terephthalate) Blend with Poly(lactic acid) as Biodegradable Food Packaging Films

The insufficient barrier performance of poly(butylene adipate-co-terephthalate) (PBAT) has seriously limited its applications in food packaging and film mulching. Herein, poly(butylene succinate-co-terephthalate) (PBST) was proposed as an alternative material and pilot-prepared with three compositional ratios. It was found that PBST possessed superior water barrier properties and comparable mechanical properties in contrast to PBAT. However, the low strength of PBST could not meet the market demands. Therefore, poly(lactic acid) (PLA) was melt-compounded with PBST to endow a robust mechanical strength for PBST/PLA blends. Then, PBST/PLA blends were prepared into biodegradable films by extrusion blowing. The mechanical, thermal, and rheological properties were investigated. With the increased content of PLA, the tensile strength (TS) of PBST/PLA increased, while the elongation at break (EB) decreased. When the content of PLA was 10 and 20%, the EB of PBST/PLA blends was above 400% and exhibited a compatible system, which was suitable for film blowing. For PBST/PLA (80/20) films, the maximum value of TS and tear strength reached 32 MPa and 124 N/mm, respectively, and displayed superior oxygen, carbon dioxide, and water vapor permeability coefficients to those of PBAT/PLA counterparts. In addition, PBST/PLA blending films with high CO2/O2 permeability ratios (6–8) effectively prolonged the banana freshness period from 7 to 14 days. Accordingly, PBST/PLA films show great potential in high-barrier application scenarios such as food packaging and agriculture mulching

High Barrier Poly(Glycolic Acid) Modified Poly(Butylene Adipate-<i>co</i>-terephthalate) Blown Films and Accelerated Ultraviolet Degradability Evaluation

The barrier performance and mechanical properties of films play important roles in handling and moisture retention when used in agricultural fields. Herein, poly­(butylene adipate-terephthalate)/polyglycolic acid (PBAT/PGA) blending films are prepared by melt-compounding and extrusion-blowing under the presence of antioxidant compounds. The results show that the incorporation of PGA improves the tensile strength, tear resistance, and water vapor barrier property. With the aid of a chain extender, no obvious phase separation and good compatibility are obtained for PBAT/PGA blends. Moreover, antioxidant compounds (1010/AP-618) greatly improve the thermal stability, which is beneficial for thermal processing. Finally, the ultraviolet (UV)-accelerated degradation behavior of PBAT/PGA are investigated. With increasing UV-irradiation days, both the tensile strength and elongation at break of the PBAT/PGA15 (AP) gradually decrease. Also, the characteristic crystalline peaks of PBAT and the initial decomposition temperature of the degraded films progressively decline, suggesting the chain breakages induced by UV irradiation. However, the water vapor barrier permeability is well-maintained due to the high crystallinity of the PGA region, indicating an excellent barrier performance of PBAT/PGA films in the service life. Therefore, the current work proposes high-barrier PBAT/PGA films and explores the photodegradation behavior for the first time, which highlights the great potential as mulching films

Real-Time Imaging Tracking of a Dual Fluorescent Drug Delivery System Based on Zinc Phthalocyanine-Incorporated Hydrogel

Real-time tracking of a drug delivery system and its therapeutic effects in vivo are crucial to designing a novel pharmaceutical system and revealing the mechanism of drug therapy. Multispectral fluorescence imaging can locate the drug and carrier simultaneously without interference. This advanced method enables the tracking of a drug delivery system. Herein, a doxorubicin (Dox) loaded zinc phthalocyanine incorporated hydrogel was developed as a dual fluorescent drug delivery system to monitor the release of the drug and the degradation of the carrier. An injectable thermosensitive hydrogel based on a four-arm poly­(ethylene glycol) (PEG)–poly­(ε-Caprolactone) (PCL) copolymer was prepared and characterized with a zinc phthalocyanine core as the drug carrier. The hydrogel degradation and drug delivery in vivo were tracked by a multispectral fluorescence imaging system in nude mice bearing hepatic tumors. Moreover, the real-time tumor inhibition progress was tracked in vivo for 18 days by bioluminescence imaging. A multispectral analysis can separate the fluorescence signals from the drug and carrier in the Dox loaded hydrogel and provide their location in the tumor tissue. The drug release and hydrogel degradation can be drastically tracked respectively without mutual interference. The fluorescence imaging results reveal improved tumor inhibitory effects of the Dox loaded hydrogel. Optical imaging allows for visible tracking of the entire drug delivery process. The Dox loaded phthalocyanine incorporated thermosensitive hydrogel is a potential visible drug delivery system for tumor therapy