Formation of Pegylated polyurethane and Lysine-coated polyurea nanoparticles obtained from O/W nano-emulsions

Polymer nanoparticles from low-energy nanoemulsions for biomedical applications

The formulation of nanoemulsions by low-energy strategies, particularly by the phase inversion composition method, and the use of these nanoemulsions as templates for the preparation of polymer nanoparticles for biomedical applications are reviewed. The methods of preparation, nature of the components in the formulation, and their impact on the physicochemical properties, drug loading, and drug release are discussed. We highlight the utilization of ethyl cellulose, poly(lactic-co-glycolic acid), and polyurethane/polyurea in the field of nanomedicine as potential drug delivery systems. Advances are still needed to achieve better control over size distribution, nanoparticle concentration, surface functionalization, and the type of polymers that can be processed.

Yeast Particles for Encapsulation of Terpenes and Essential Oils

Terpenes and essential oils are materials of great commercial use due to their broad spectra of antibacterial, antifungal, membrane permeation enhancement and antioxidant biological properties, as well as for their use as flavors and fragrances. Yeast particles (YPs) are 3-5 µm hollow and porous microspheres, a byproduct of some food-grade yeast (Saccharomyces cerevisiae) extract manufacturing processes, that have been used for the encapsulation of terpenes and essential oils with high payload loading capacity (up to 500% weight) and efficiency, providing stability and sustained-release properties. This review focuses on encapsulation approaches for the preparation of YP-terpene and essential oil materials that have a wide range of potential agricultural, food and pharmaceutical applications.

Achieving Win-Win Ecotoxicological Safety and Fungicidal Activity of Pyraclostrobin-Loaded Polyurea Microcapsules by Selecting Proper Polyamines

The fungicide pyraclostrobin is highly toxic to aquatic organisms. Microencapsulation is an effective way to reduce the exposure of pyraclostrobin to aquatic organisms but it also reduces the contact probability between the fungicide and plant pathogens. Hence, winning a balance between the toxicity and bioactivity of pyraclostrobin is very necessary. In this study, triethylenetetramine (TETA), ethylenediamine (EDA), hexamethylenediamine (HAD), and isophoronediamine (IPDA) were selected as cross-linkers to prepare the pyraclostrobin-loaded polyurea microcapsules (PU-MCs) by interfacial polymerization. TETA formed the shells with the highest degree of cross-linking, the slowest release profile, and the best protection against ultraviolet (UV). In terms of MCs fabricated by diamines, higher leaking, weaker UV resistance of the shells was observed with increasing carbon skeleton. TETA-MCs showed the highest safety to zebrafish (LC₅₀ of 10.086 mg/L), whereas EDA-MCs, HAD-MCs, and IPDA-MCs were 5.342, 3.967, and 0.767 mg/L, respectively. TETA-MCs had the best long-term disease management, while the control efficacies of other MCs were higher at the early stage of disease development. Overall, a balance between the aquatic toxicities and fungicidal activities of pyraclostrobin-loaded PU-MCs could be reached through a simple selection of polyamines in the fabrication.

Preparation of coffee oil-algae oil-based nanoemulsions and the study of their inhibition effect on UVA-induced skin damage in mice and melanoma cell growth

Coffee grounds, a waste by-product generated after making coffee, contains approximately 15% coffee oil which can be used as a raw material in cosmetics. Algae oil rich in docosahexaenoic acid (DHA) has been demonstrated to possess anticancer and anti-inflammation functions. The objectives of this study were to develop a gas chromatography-mass spectrometry (GC-MS) method for the determination of fatty acids in coffee oil and algae oil and prepare a nanoemulsion for studying its inhibition effect on ultraviolet A-induced skin damage in mice and growth of melanoma cells B16-F10. A total of 8 and 5 fatty acids were separated and quantified in coffee oil and algae oil by GC-MS, respectively, with linoleic acid (39.8%) dominating in the former and DHA (33.9%) in the latter. A nanoemulsion with a particle size of 30 nm, zeta potential -72.72 mV, and DHA encapsulation efficiency 100% was prepared by using coffee oil, algae oil, surfactant (20% Span 80 and 80% Tween 80), and deionized water. Differential scanning calorimetry (DSC) analysis revealed a high stability of nanoemulsion when heated up to 110°C at a pH 6, whereas no significant changes in particle size distribution and pH occurred over a 90-day storage period at 4°C. Animal experiments showed that a dose of 0.1% coffee oil-algae oil nanoemulsion was effective in mitigating trans-epidermal water loss, skin erythema, melanin formation, and subcutaneous blood flow. Cytotoxicity test implied effective inhibition of melanoma cell growth by nanoemulsion with an IC50 value of 26.5 µg/mL and the cell cycle arrested at G2/M phase. A dose-dependent upregulation of p53, p21, cyclin B, and cyclin A expressions and downregulation of CDK1 and CDK2 occurred. Also, both Bax and cytochrome c expressions were upregulated and bcl-2 expression downregulated, accompanied by a rise in caspase-3, caspase-8, and caspase-9 activities for apoptosis execution. Collectively, the apoptosis pathway of melanoma cells B16-F10 may involve both mitochondria and death receptor.

Non-Isocyanate Polyurethane Soft Nanoparticles Obtained by Surfactant-Assisted Interfacial Polymerization

Polyurethanes (PUs) are considered ideal candidates for drug delivery applications due to their easy synthesis, excellent mechanical properties, and biodegradability. Unfortunately, methods for preparing well-defined PU nanoparticles required miniemulsion polymerization techniques with a nontrivial control of the polymerization conditions due to the inherent incompatibility of isocyanate-containing monomers and water. In this work, we report the preparation of soft PU nanoparticles in a one-pot process using interfacial polymerization that employs a non-isocyanate polymerization route that minimizes side reactions with water. Activated pentafluorophenyl dicarbonates were polymerized with diamines and/or triamines by interfacial polymerization in the presence of an anionic emulsifier, which afforded non-isocyanate polyurethane (NIPU) nanoparticles with sizes in the range of 200-300 nm. Notably, 5 wt % of emulsifier was required in combination with a trifunctional amine to achieve stable PU dispersions and avoid particle aggregation. The versatility of this polymerization process allows for incorporation of functional groups into the PU nanoparticles, such as carboxylic acids, which can encapsulate the chemotherapeutic doxorubicin through ionic interactions. Altogether, this waterborne synthetic method for functionalized NIPU soft nanoparticles holds great promise for the preparation of drug delivery nanocarriers.

Cationic ring-opening polymerization of protected oxazolidine imines resulting in gradient copolymers of poly(2-oxazoline) and poly(urea)

Synthesis of well-defined poly(urea)-poly(2-ethyl-2-oxazoline) gradient copolymers.

Interfacial polymerization of conductive polymers: Generation of polymeric nanostructures in a 2-D space

In the recent advances in the field of conductive polymers, the fibrillar or needle shaped nanostructures of polyaniline and polypyrrole have attracted significant attention due to the potential advantages of organic conductors that exhibit low-dimensionality, uniform size distribution, high crystallinity and improved physical properties compared to their bulk or spherically shaped counterparts. Carrying the polymerization reaction in a restricted two dimensional space, instead of the three dimensional space of the one phase solution is an efficient method for the synthesis of polymeric nanostructures with narrow size distribution and small diameter. Ultra-thin nanowires and nanofibers, single crystal nanoneedles, nanocomposites with noble metals or carbon nanotubes and layered materials can be efficiently synthesized with high yield and display superior performance in sensors and energy storage applications. In this critical review we will focus not only on the interfacial polymerization methods that leads to polymeric nanostructures and composites and their properties, but also on the mechanism and the physico-chemical processes that govern the diffusion and reactivity of molecules and nanomaterials at an interface. Recent advances for the synthesis of conductive polymer composites with an interfacial method for energy storage applications and future perspectives are presented.

Multifunctionalized polyurethane-polyurea nanoparticles: hydrophobically driven self-stratification at the o/w interface modulates encapsulation stability

Polyurethane-polyurea (PUUa) reactive prepolymers with adjusted hydrophobic and hydrophilic dangling chains to achieve multiwalled sub-30 nm nanoparticles are presented. The combination of an amphiphilic and a hydrophobic prepolymer at the oil-water interface creates a stratified shell by hydrophobic interactions. These novel nanostructures enhance the encapsulation stability of lipophilic compounds compared to monowalled nanostructures and facilitate the selective and ordered functionalization along the multiwalled shell with bioactive motifs. As proof of concept, PUUa nanoparticles have been engineered with disulfide bonds and an α_vβ₃ integrin-selective cyclic RGD peptide (cRGDfK) providing our system with glutathione (GSH) triggered controlled release and cell targeting specificity to U87 tumor cells.

Synthesis of polyurea–polyether nanoparticles via spontaneous nanoprecipitation

Synthesis of polyurea–polyether core–shell nano-particles via spontaneous precipitation.

Fabrication of polymer nanocapsules with controllable oligo(ethylene glycol) densities, permeation properties and robustly crosslinked walls

P(TMSPMA-co-OEGMA) nanocapsules with controllable oligo(ethylene glycol) (OEG) densities and robustly cross-linked structures were successfully fabricated from the cross-linkable copolymer, poly[3-(trimethoxysilyl)propyl methacrylate-co-oligo(ethylene glycol) methacrylate] (P(TMSPMA-co-OEGMA)). The densities of OEG segments of the resultant P(TMSPMA-co-OEGMA) nanocapsules could be easily controlled by tuning the OEGMA contents of copolymer P(TMSPMA-co-OEGMA). The microenvironments of the P(TMSPMA-co-OEGMA) nanocapsules were determined to be hydrophobic. It was demonstrated that hydrophobic pyrene could be in situ loaded into the P(TMSPMA-co-OEGMA) nanocapsules during the fabrication procedure. The release rates of pyrene from the P(TMSPMA-co-OEGMA) nanocapsules were dependent on the contents of OEGMA, indicating that the permeation properties of P(TMSPMA-co-OEGMA) nanocapsules could be tuned by varying the cross-linked densities of the nanocapsule walls. It was further demonstrated that other functional groups could be easily incorporated into the resultant polymer nanocapsules by using the similar procedure. The preparation of polymer nanocapsules with various functionalities and robustly cross-linked walls without any further post modification process, any sacrificial core and surfactant would be beneficial from scientific and technical point of views.