Environmental pollution arising from plastic waste is a major global concern. Plastic macroparticles, microparticles, and nanoparticles have the potential to affect marine ecosystems and human health. It is generally accepted that microplastic particles are not harmful or at best minimal to human health. However direct contact with microplastic particles may have possible adverse effect in cellular level. Primary polystyrene (PS) particles were the focus of this study, and we investigated the potential impacts of these microplastics on human health at the cellular level. We determined that PS particles were potential immune stimulants that induced cytokine and chemokine production in a sizedependent and concentration-dependent manner. Microplastic particles can be divided into two categories, primary and secondary. Plastic particles less than 5 mm in diameter are considered microplastics 1. Although local and national governments in North America took action in 2015 to regulate the manufacture of microbeads, microplastic particles are still produced in other parts of the world 2. Primary microplastic particles are intentionally manufactured at the microscale and are key ingredients in scrubs 3 , handwashing soaps 4 , cleansers 5 , toothpastes 6 , and biomedical products 7. Primary microplastic particles, particularly those between 1 and 5 µm in diameter, are spherical and often made of polypropylene (PP), polystyrene (PS), or polyethylene (PE). Unlike primary microplastic particles, secondary microplastic particles are generated through the fragmentation of plastic litter 8-10. Plastic debris is the primary source of secondary microplastic particles found in the ocean and soil, because the debris breaks down into mesoparticles and macroparticles. Ultraviolet (UV) radiation from the sun and physical forces degrade these particles into plastic microparticles and nanoparticles 11,12. A recent study investigated the fragmentation of PS coffee cup lids, disposable plates, and PS foams irradiated with simulated UV light to determine the degradation mechanism 13. Seafood is also a potential source of particulate plastic contaminants 14-18. Anthropogenic debris, including plastic particles and fibers, was found in over 20% of individual shellfish and the gastrointestinal (GI) tracts of fish in a 2015 study 19. The ingestion of microplastics by fish and shellfish has been demonstrated in several studies 16,18,20. Food, food containers, everyday products (personal care products), biomedical products, and drinking water are not the main sources of particulate plastic contaminants. However, they may be continuous sources of plastic particles 21-24. For example, one study found microplastic fragments in all types of returnable and single-use plastic bottles 24. Other examples include facial scrubs that are commonly used for exfoliation. It is estimated that 1.1 million women in the UK use these scrubs every day. A typical amount for daily use is 5 mL, which contains between 4,594 and 94,500 microplastic particles 4,5. Additio...

BackgroundThe main purpose of drug delivery systems is to deliver the drugs at the appropriate concentration to the precise target site. Recently, the application of a thin film in the field of drug delivery has gained increasing interest because of its ability to safely load drugs and to release the drug in a controlled manner, which improves drug efficacy. Drug loading by the thin film can be done in various ways, depending on type of the drug, the area of exposure, and the purpose of drug delivery.Main textThis review summarizes the various methods used for preparing thin films with drugs via Layer-by-layer (LbL) assembly. Furthermore, additional functionalities of thin films using surface modification in drug delivery are briefly discussed. There are three types of methods for preparing a drug-carrying multilayered film using LbL assembly. First methods include approaches for direct loading of the drug into the pre-fabricated multilayer film. Second methods are preparing thin films using drugs as building blocks. Thirdly, the drugs are incorporated in the cargo so that the cargo itself can be used as the materials of the film.ConclusionThe appropriate designs of the drug-loaded film were produced in consideration of the release amounts and site of the desired drug. Furthermore, additional surface modification using the LbL technique enabled the preparation of effective drug delivery carriers with improved targeting effect. Therefore, the multilayer thin films fabricated by the LbL technique are a promising candidate for an ideal drug delivery system and the development possibilities of this technology are infinite.

Intravenous administration of mesenchymal stem cells (MSCs) has served as a clinical intervention for inflammatory diseases. Once entered to blood circulation, MSCs are exposed to a harsh environment which sharply decreases cell viability due to the fact that injected cells, being susceptible to shear stress, are subjected to the high velocities of the bloodstream and lack of proper mechanical support that keeping them in an attachment-deprived state. Here, we coated the nanofilm onto viable MSCs by depositing poly-l-lysine and hyaluronic acid molecules along with arginine-glycine-aspartic acid (RGD peptide) as building blocks to protect cells from shear stress and stabilize them in a single cell, suspension state. In this article, we found that nanofilm-coated cells showed significantly increased cell survival in vitro and in vivo, which was also supported by the activation of survival-related protein, Akt. The coated nanofilm did not interfere with the stemness of MSCs which was determined based on the colony forming unit-fibroblast (CFU-F) assay and in vitro differentiation potential. Because of the characteristics of films showing light molecular deposition density, flexibility, and looseness, application of nanofilms did not block cell migration. When the cells were administrated intravenously, the nanofilm coated MSCs not only prolonged blood circulation lifetime but also showed increased stem cell recruitment to injured tissues in the muscle injury in vivo model, due to prolonged survival. Surface modification of MSCs using nanofilms successfully modulated cell activity enabling them to survive the anoikis-inducing state, and this can provide a valuable tool to potentiate the efficacy of MSCs for in vivo cell therapy.

Poly(ethylene glycol) (PEG) has attracted significant interest because of its superior antifouling properties, water solubility, and biocompatibility. However, the translation of its antifouling properties onto target surfaces has been challenging because of its limited functionality. Herein, the superior antifouling properties of PEG-based block copolyethers functionalized with catechol, a mussel-inspired, versatile moiety for coating surfaces, were evaluated within a framework of polyethers exclusively. A series of catechol-functionalized polyethers with diverse molecular weights and catechol contents were synthesized via anionic ringopening polymerization in a controlled manner. The versatile adsorption and antifouling effects of block copolyethers were evaluated using a quartz crystal microbalance with dissipation. Furthermore, the crucial role of the topology (loop vs brush) in the antifouling properties was analyzed via a surface force apparatus and direct atomistic molecular dynamics simulations. This study demonstrates that the catechol-functionalized triblock copolymer shows excellent antifouling properties, exhibiting its great potential in various biomedical applications.

Over the past decade, much progress has been made in the application of multifunctional membranes with special wettability for the separation of oil–water mixtures. This progress has been driven by frequent oil spill accidents and oily wastewater, which are enormous threats to the vulnerable aquatic environment. The design of permeable superwettable membranes for oil–water separation has been inspired by the development of highly wetting/nonwetting interfaces, but these membranes are susceptible to factors such as mechanical forces, chemical corrosion, biological fouling, and other environmental influences. Considering the complex and harsh environments that superwettable membranes must endure during the separation process, membrane durability against the loss of superwettability is critical in prolonging the life of an oil–water filtration system. Although significant advances in superwettable membranes have been made, the robustness issue remains challenging and has become a focus of many investigations. Covering nearly all publications concerning “robust, durable, usable, resistant, tolerant, or antifouling oil–water separation” published in the last five years, this work is intended as an introduction for new researchers wishing to create durable superwettable membranes for oil–water separation, as well as providing perspectives and guidance for future research in several logical directions.

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Exogeneous nitric oxide (NO) delivery is a promising therapeutic method because NO is a significant cell signaling molecule to control physiological functions. A major challenge for NO delivery is to control release due to the fast diffusion properties of gaseous molecules with low molecular weight. It is important in biomedical applications to mitigate initial burst emissions because higher concentrations of reactive NO cause cytotoxicity and tissue damage. In this study, a nanoparticle system is developed to control spontaneous gas release on the basis of surface-modified silica nanoparticles (Si NPs) by branched polyethylene imine (BPEI). BPEI is not only a scaffold of N-diazeniumdiolatesa type of NO donorand but also a stabilizer of donors by molecular interactions with nearby amine groups. With the sustained-release manner, BPEI-coated NO-releasing Si NPs (BPEI-NO NPs) have multifunctional properties, including bactericidal efficacies as well as good cell viability for human cells. An improved ocular wound recovery is achieved in the mouse keratitis model. This study demonstrates the great potential of the NO-releasing NP as a multifunctional nanotherapeutic in biomedical applications.

The ability to control drug loading and release is the most important feature in the development of medical devices. In this research, we prepared a functional nanocoating technology to incorporate a drug-release layer onto a desired substrate. The multilayer films were prepared using chitosan (CHI) and carboxymethyl cellulose (CMC) polysaccharides by the layer-by-layer (LbL) method. By using chemical cross-linking to change the inner structure of the assembled multilayer, we could control the extent of drug loading and release. The cross-linked multilayer film had a porous structure and enhanced water wettability. Interestingly, more of the small-molecule drug was loaded into and released from the non-cross-linked multilayer film, whereas more of the macromolecular drug was loaded into and released from the cross-linked multilayer film. These results indicate that drug loading and release can be easily controlled according to the molecular weight of the desired drug by changing the structure of the film.