Preparation of mango peel-waste pectin-based nanofibers by solution blow spinning (SBS)

An essential prerequisite for successful solution blow spinning (SBS) is the presence of effective molecular entanglements of polymers in the solution. However, the fabrication of biopolymer fibers is not as straightforward as synthetic polymers. Particularly for biopolymers such as pectin, molecular entanglements are essential but insufficient for successful spinning through the SBS production method. Such a challenge is due to the biopolymer's complex nature. However, incorporating an easily spinnable polymer precursor, such as polyacrylonitrile (PAN), to pectin effectively enabled the production of fibers from the SBS process. In this process, PAN-assisted pectin nanofibers are produced with average diameters ranging from 410.75 ± 3.73 to 477.09 ± 6.60 nm using a feed flow rate of 5 ml h^-1, air pressure of 3 bars, syringe tip to collector distance at 30 cm, and spinning time of 10 min. PAN in DMSO solvent at different volume ratios (i.e. 35%-55% v/v) was critical in assisting pectin to produce nanofibers. The addition of a high molecular weight polymer, PAN, to pectin also improved the viscoelasticity of the solution, eventually contributing to its successful SBS process. Furthermore, the composite SBS-spun fibers obtained suggest that its formation is concentration-dependent.

Elucidating the surface macroplastic load, types and distribution in mangrove areas around Cebu Island, Philippines and its policy implications

The Philippines is identified as one of the major marine plastic litter polluters in the world with a discharge of approximately 0.75 million tons of marine plastic debris per year. However, the extent of the plastic problem is yet to be defined systematically because of limited research. Thus, this study aims to quantify plastic litter occurrence in mangrove areas as they function as sinks for plastic litter due to their inherent nature of trapping plastics. To define the extent of marine plastic pollution on an island scale, mangrove areas in 14 municipalities around Cebu Island were sampled, with 3 to 9 transects in each site depending on the length of coastline covered by mangroves. Sampling and characterization of both plastics and the mangrove ecosystem was performed in three locations along the transect - landward, middle, and seaward. A total of 4501 plastic items were sampled throughout the study sites with an average of 1.29 ± 0.67 items/m² (18.07 ± 8.79 g/m²). The average distribution of plastic loads were 2.68 ± 1.9 items/m² (38.52 ± 25.35 g/m²), 0.27 ± 0.10 items/m² (6.65 ± 4.67 g/m²), and 0.94 ± 0.61 items/m² (9.04 ± 4.28 g/m²) for the landward, middle, and seaward locations, respectively. The most frequent plastic types found were i) packaging, ii) plastic bags and iii) plastic fragments. The plastic loads and types suggest that most plastic wastes trapped in mangroves come from the nearby communities. Fishing-related plastics originated from the sea and were transported across the mangrove breadth. The findings confirm that mangroves are major traps of plastic litter that might adversely affect the marine ecosystem. The study underscores the urgent need for waste mitigation measures, including education, community engagement, infrastructure, technological solutions and supporting policies.

On the progress of 3D-printed hydrogels for tissue engineering

ABSTRACT

Additive manufacturing or more commonly known as 3D printing, is currently driving innovations and applications in diverse fields such as prototyping, manufacturing, aerospace, education, and medicine. Recent technological and materials research breakthroughs have enabled 3D bioprinting, where biomaterials and cells are used to create scaffolds and functional living tissues (e.g. skin, cartilage, etc.). This prospective focuses on the classification and applications of hydrogels, and design considerations in their production (i.e. physical and biological parameters). The materials for 3D printing of hydrogels, such as biopolymers, synthetic polymers, and nanocomposites, are mainly discussed. More importantly, future perspectives on 3D printing hydrogels including new materials, 4D printing, emerging printing technologies, etc. and their importance in biomedical and bioengineering applications are discussed.