Recent Advances in the Emulsion Solvent Evaporation Technique for the Preparation of Nanoparticles and Nanocapsules

Self-Reinforced Biocomposites Made from Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV): An Innovative Approach to Sustainable Packaging Production through Melt Processing

The production of self-reinforced composites allows for a targeted tailoring of the property profile for specific applications and offers the physical-mechanical advantages of a synergistic combination of the two components with a high value in terms of their end-of-life scenarios. This study deals with the preparation and evaluation of self-reinforced biocomposites of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with PHBV microparticles produced for the first time by industry-oriented melt processing. First, microparticles with a size of 4 μm were prepared and characterized by using the miniemulsion/evaporation technique. These microparticles were then incorporated into the PHBV matrix by extrusion and injection molding. Electron microscopy revealed particles in biocomposites. The results indicate heterogeneous nucleation, leading to higher crystallinity at higher melting temperatures. This leads to a slight embrittlement and an improvement of the barrier properties against oxygen and water vapor. These industrially produced biocomposites benefit from particles by showing, among other things, higher barrier properties while retaining their green character, making them promising and easily accessible candidates for future packaging applications.

Revolutionizing the female reproductive system research using microfluidic chip platform

Comprehensively understanding the female reproductive system is crucial for safeguarding fertility and preventing diseases concerning women's health. With the capacity to simulate the intricate physio- and patho-conditions, and provide diagnostic platforms, microfluidic chips have fundamentally transformed the knowledge and management of female reproductive health, which will ultimately promote the development of more effective assisted reproductive technologies, treatments, and drug screening approaches. This review elucidates diverse microfluidic systems in mimicking the ovary, fallopian tube, uterus, placenta and cervix, and we delve into the culture of follicles and oocytes, gametes' manipulation, cryopreservation, and permeability especially. We investigate the role of microfluidics in endometriosis and hysteromyoma, and explore their applications in ovarian cancer, endometrial cancer and cervical cancer. At last, the current status of assisted reproductive technology and integrated microfluidic devices are introduced briefly. Through delineating the multifarious advantages and challenges of the microfluidic technology, we chart a definitive course for future research in the woman health field. As the microfluidic technology continues to evolve and advance, it holds great promise for revolutionizing the diagnosis and treatment of female reproductive health issues, thus propelling us into a future where we can ultimately optimize the overall wellbeing and health of women everywhere.

Corrosion-Responsive Self-Healing Coatings

Organic coatings are one of the most popular and powerful strategies for protecting metals against corrosion. They can be applied in different ways, such as by dipping, spraying, electrophoresis, casting, painting, or flow coating. They offer great flexibility of material designs and cost effectiveness. Moreover, self-healing has evolved as a new research topic for protective organic coatings in the last two decades. Responsive materials play a crucial role in this new research field. However, for targeting the development of high-performance self-healing coatings for corrosion protection, it is not sufficient just to focus on smart responsive materials and suitable active agents for self-healing. A better understanding of how coatings can react on different stimuli induced by corrosion, how these stimuli can spread in the coating, and how the released agents can reach the corroding defect is also of high importance. Such knowledge would allow the design of coatings that are optimized for specific applications. Herein, the requirements and possibilities from the corrosion and synthesis perspectives for designing materials for preparing self-healing coatings for corrosion protection are discussed.

Exploring Various Techniques for the Chemical and Biological Synthesis of Polymeric Nanoparticles

Nanoparticles (NPs) have remarkable properties for delivering therapeutic drugs to the body's targeted cells. NPs have shown to be significantly more efficient as drug delivery carriers than micron-sized particles, which are quickly eliminated by the immune system. Biopolymer-based polymeric nanoparticles (PNPs) are colloidal systems composed of either natural or synthetic polymers and can be synthesized by the direct polymerization of monomers (e.g., emulsion polymerization, surfactant-free emulsion polymerization, mini-emulsion polymerization, micro-emulsion polymerization, and microbial polymerization) or by the dispersion of preformed polymers (e.g., nanoprecipitation, emulsification solvent evaporation, emulsification solvent diffusion, and salting-out). The desired characteristics of NPs and their target applications are determining factors in the choice of method used for their production. This review article aims to shed light on the different methods employed for the production of PNPs and to discuss the effect of experimental parameters on the physicochemical properties of PNPs. Thus, this review highlights specific properties of PNPs that can be tailored to be employed as drug carriers, especially in hospitals for point-of-care diagnostics for targeted therapies.

New Analytical Approaches for Effective Quantification and Identification of Nanoplastics in Environmental Samples

Nanoplastics (NPs) are a rapidly developing subject that is relevant in environmental and food research, as well as in human toxicity, among other fields. NPs have recently been recognized as one of the least studied types of marine litter, but potentially one of the most hazardous. Several studies are now being reported on NPs in the environment including surface water and coast, snow, soil and in personal care products. However, the extent of contamination remains largely unknown due to fundamental challenges associated with isolation and analysis, and therefore, a methodological gap exists. This article summarizes the progress in environmental NPs analysis and makes a critical assessment of whether methods from nanoparticles analysis could be adopted to bridge the methodological gap. This review discussed the sample preparation and preconcentration protocol for NPs analysis and also examines the most appropriate approaches available at the moment, ranging from physical to chemical. This study also discusses the difficulties associated with improving existing methods and developing new ones. Although microscopical techniques are one of the most often used ways for imaging and thus quantification, they have the drawback of producing partial findings as they can be easily mixed up as biomolecules. At the moment, the combination of chemical analysis (i.e., spectroscopy) and newly developed alternative methods overcomes this limitation. In general, multiple analytical methods used in combination are likely to be needed to correctly detect and fully quantify NPs in environmental samples.

Cellulose nanocarriers via miniemulsion allow Pathogen-Specific agrochemical delivery

The current spraying of agrochemicals is unselective and ineffective, consuming a high amount of fungicides, which endangers the environment and human health. Cellulose-based nanocarriers (NCs) are a promising tool in sustainable agriculture and suitable vehicles for stimuli-responsive release of agrochemicals to target cellulase-segregating fungi, which cause severe plant diseases such as Apple Canker. Herein, cellulose was modified with undec-10-enoic acid to a hydrophobic and cross-linkable derivative, from which NCs were prepared via thiol-ene addition in miniemulsion. During the crosslinking reaction, the NCs were loaded in situ with hydrophobic fungicides, Captan and Pyraclostrobin. NCs with average sizes ranging from 200 to 300 nm and an agrochemical-load of 20 wt% were obtained. Cellulose-degrading fungi, e.g. Neonectria. ditissima which is responsible for Apple Canker, lead to the release of fungicides from the aqueous NC dispersions suppressing fungal growth. In contrast, the non-cellulase segregating fungi, e.g. Cylindrocladium buxicola, do not degrade the agrochemical-loaded NCs. This selective action against Apple Canker fungi, N. ditissima, proves the efficacy of NC-mediated drug delivery triggered by degradation in the exclusive presence of cellulolytic fungi. Cellulose NCs represent a sustainable alternative to the current unselective spraying of agrochemicals that treats many crop diseases ineffectively.

Halochromic Polymer Nanosensors for Simple Visual Detection of Local pH in Coatings

Replacing metallic structures before critical damage is beneficial for safety and for saving energy and resources. One simple approach consists in visually monitoring the early stage of corrosion, and related change of pH, of coated metals. We prepare smart nanoparticle additives for coatings which act as a pH sensor. The nanoparticles are formed with a terpolymer containing two dyes as side chains, acting as donor and acceptor for a FRET process. Real time monitoring of the extent of localized corrosion on metallic structures is then carried out with a smartphone camera. Colored pH mapping can be then manually retrieved by an operator or automatically recorded by a surveillance camera.

Bottom-Up Design of Composite Supraparticles for Powder-Based Additive Manufacturing

Additive manufacturing promises high flexibility and customized product design. Powder bed fusion processes use a laser to melt a polymer powder at predefined locations and iterate the scheme to build 3D objects. The design of flowable powders is a critical parameter for a successful fabrication process that currently limits the choice of available materials. Here, a bottom-up process is introduced to fabricate tailored polymer- and composite supraparticles for powder-based additive manufacturing processes by controlled aggregation of colloidal primary particles. These supraparticles exhibit a near-spherical shape and tailored composition, morphology, and surface roughness. These parameters can be precisely controlled by the mixing and size ratio of the primary particles. Polystyrene/silica composite particles are chosen as a model system to establish structure-property relations connecting shape, morphology, and surface roughness to the adhesion within the powder, which is accessed by tensile strength measurements. The adhesive properties are then connected to powder flowability and it is shown that the resulting powders allow the formation of dense powder films with uniform coverage. Finally, successful powder bed fusion is demonstrated by producing macroscopic single layer specimens with uniform distribution of nanoscale silica additives.

Enhanced photocatalytic hydrogen evolution from organic semiconductor heterojunction nanoparticles

Photocatalysts formed from a single organic semiconductor typically suffer from inefficient intrinsic charge generation, which leads to low photocatalytic activities. We demonstrate that incorporating a heterojunction between a donor polymer (PTB7-Th) and non-fullerene acceptor (EH-IDTBR) in organic nanoparticles (NPs) can result in hydrogen evolution photocatalysts with greatly enhanced photocatalytic activity. Control of the nanomorphology of these NPs was achieved by varying the stabilizing surfactant employed during NP fabrication, converting it from a core-shell structure to an intermixed donor/acceptor blend and increasing H2 evolution by an order of magnitude. The resulting photocatalysts display an unprecedentedly high H2 evolution rate of over 60,000 µmol h-1 g-1 under 350 to 800 nm illumination, and external quantum efficiencies over 6% in the region of maximum solar photon flux.

Regulating Payload Release from Hybrid Nanocapsules with Dual Silica/Polycaprolactone Shells

We describe a facile strategy to synthesize hybrid nanocapsules with an oil core for hindering interactions between payloads and silica shell. Polycaprolactone/silica nanocapsules are synthesized by an interfacial sol-gel process occurring simultaneously with internal phase separation of the polymer produced by a miniemulsion-solvent evaporation technique. The localization of the polycaprolactone in the nanocapsules is depending on the ratio between polymer and silica. Formation of hybrid nanocapsules is found to significantly hinder interactions of drugs such as ibuprofen and carbamazepine with the silica surface.

Trastuzumab-Coated Nanoparticles Loaded With Docetaxel for Breast Cancer Therapy

Docetaxel (DTX) is commonly used for breast cancer treatment. Tween 80 used for DTX dissolution in its clinical formulation causes severe hypersensitivity and other adverse reactions. In this study, trastuzumab (Tmab)-coated lipid-polymer hybrid nanoparticles (PLNs) were prepared, composed of poly (d, l-lactide-co-glycolide), PLGA; polyethylenimine (PEI); and lipids. The PLGA/PEI/lipid formed a hydrophobic core, while Tmab was electrostatically adsorbed on the surface of the PLNs as a ligand that targets human epidermal growth factor receptor 2 (HER2)-positive breast cancer cells. The resulting PLNs, electrostatically adsorbed Tmab-bearing PLGA/PEI/lipid nanoparticles (eTmab-PPLNs), had a mean particle size of 217.4 ± 13.36 nm, a ζ potential of 0.056 ± 0.315 mV, and good stability. In vitro, the eTmab-PPLNs showed increased cytotoxicity in HER2-postive BT474 cells but not in HER2-negative MCF7 cells. Studies of the ability of eTmab-PPLNs to target HER2 were performed. The uptake of eTmab-PPLNs was shown to be dependent on HER2 expression level. Therefore, eTmab-PPLNs provide a promising therapeutic for the treatment of breast cancer.

Melatonin loaded with bacterial cellulose nanofiber by Pickering-emulsion solvent evaporation for enhanced dissolution and bioavailability

The objective of the present work aimed to explore the potential of bacterial cellulose (BC) for oral delivery of melatonin (MLT), a natural hormone that faces problems of low solubility and oral bioavailability. BC was hydrolyzed by sulfuric acid followed by the oxidation to prepare bacterial cellulose nanofiber suspension (BCNs). Melatonin-loaded bacterial cellulose nanofiber suspension (MLT-BCNs) was prepared by emulsion solvent evaporation method. The properties of freeze-dried BCs and MLT-BCNs were studied by Fluorescence microscopy (FM), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermo gravimetric (TG). The results indicated that the fibers in BCNs became short and thin compared with BC, MLT in MLT-BCNs was uniformly distributed, both BCNs and MLT-BCNs have good thermodynamic stability. The MLT-BCNs showed more rapid dissolution MLT rates compared to the commercially available MLT in SGF and SIF, the dissolution of the cumulative release rate was about 2.1 times of the commercially available MLT. The oral bioavailability of MLT-BCNs in rat was about 2.4 times higher than the commercially available MLT. Thus, MLT-BCNs could act as promising delivery with enhanced dissolution and bioavailability for MLT after oral administration.

Designing Smart Polymer Conjugates for Controlled Release of Payloads

Incorporating labile bonds inside polymer backbone and side chains yields interesting polymer materials that are responsive to change of environmental stimuli. Drugs can be conjugated to various polymers through different conjugation linkages and spacers. One of the key factors influencing the release profile of conjugated drugs is the hydrolytic stability of the conjugated linkage. Generally, the hydrolysis of acid-labile linkages, including acetal, imine, hydrazone, and to some extent β-thiopropionate, are relatively fast and the conjugated drug can be completely released in the range of several hours to a few days. The cleavage of ester linkages are usually slow, which is beneficial for continuous and prolonged release. Another key structural factor is the water solubility of polymer-drug conjugates. Generally, the release rate from highly water-soluble prodrugs is fast. In prodrugs with large hydrophobic segments, the hydrophobic drugs are usually located in the hydrophobic core of micelles and nanoparticles, which limits the access to the water, hence lowering significantly the hydrolysis rate. Finally, self-immolative polymers are also an intriguing new class of materials. New synthetic pathways are needed to overcome the fact that much of the small molecules produced upon degradation are not active molecules useful for biomedical applications.

Building the design, translation and development principles of polymeric nanomedicines using the case of clinically advanced poly(lactide(glycolide))-poly(ethylene glycol) nanotechnology as a model: An industrial viewpoint

The design of the first polymeric nanoparticles could be traced back to the 1970s, and has thereafter received considerable attention, as evidenced by the significant increase of the number of articles and patents in this area. This review article is an attempt to take advantage of the existing literature on the clinically tested and commercialized biodegradable PLA(G)A-PEG nanotechnology as a model to propose quality building and outline translation and development principles for polymeric nano-medicines. We built such an approach from various building blocks including material design, nano-assembly - i.e. physicochemistry of drug/nano-object association in the pharmaceutical process, and release in relevant biological environment - characterization and identification of the quality attributes related to the biopharmaceutical properties. More specifically, as envisaged in a translational approach, the reported data on PLA(G)A-PEG nanotechnology have been structured into packages to evidence the links between the structure, physicochemical properties, and the in vitro and in vivo performances of the nanoparticles. The integration of these bodies of knowledge to build the CMC (Chemistry Manufacturing and Controls) quality management strategy and finally support the translation to proof of concept in human, and anticipation of the industrialization takes into account the specific requirements and biopharmaceutical features attached to the administration route. From this approach, some gaps are identified for the industrial development of such nanotechnology-based products, and the expected improvements are discussed. The viewpoint provided in this article is expected to shed light on design, translation and pharmaceutical development to realize their full potential for future clinical applications.

Stabilization of Inverse Miniemulsions by Silyl-Protected Homopolymers

Inverse (water-in-oil) miniemulsions are an important method to encapsulate hydrophilic payloads such as oligonucleotides or peptides. However, the stabilization of inverse miniemulsions usually requires block copolymers that are difficult to synthesize and/or cannot be easily removed after transfer from a hydrophobic continuous phase to an aqueous continuous phase. We describe here a new strategy for the synthesis of a surfactant for inverse miniemulsions by radical addition⁻fragmentation chain transfer (RAFT) polymerization, which consists in a homopolymer with triisopropylsilyl protecting groups. The protecting groups ensure the efficient stabilization of the inverse (water-in-oil, w/o) miniemulsions. Nanocapsules can be formed and the protecting group can be subsequently cleaved for the re-dispersion of nanocapsules in an aqueous medium with a minimal amount of additional surfactant.

Nanocontainers in and onto Nanofibers

Hierarchical structure is a key feature explaining the superior properties of many materials in nature. Fibers usually serve in textiles, for structural reinforcement, or as support for other materials, whereas spherical micro- and nanoobjects can be either highly functional or also used as fillers to reinforce structure materials. Combining nanocontainers with fibers in one single object has been used to increase the functionality of fibers, for example, antibacterial and thermoregulation, when the advantageous properties given by the encapsulated materials inside the containers are transferred to the fibers. Herein we focus our discussion on how the hierarchical structure composed of nanocontainers in nanofibers yields materials displaying advantages of both types of materials and sometimes synergetical effects. Such materials can be produced by first carefully designing nanocontainers with defined morphology and chemistry and subsequently electrospinning them to fabricate nanofibers. This method, called colloid-electrospinning, allows for marrying the properties of nanocontainers and nanofibers. The obtained fibers could be successfully applied in different fields such as catalysis, optics, energy conversion and production, and biomedicine. The miniemulsion process is a convenient approach for the encapsulation of hydrophobic or hydrophilic payloads in nanocontainers. These nanocontainers can be embedded in fibers by the colloid-electrospinning technique. The combination of nanocontainers with nanofibers by colloid-electrospinning has several advantages. (1) The fiber matrix serves as support for the embedded nanocontainers. For example, through combining catalysts nanoparticles with fiber networks, the catalysts can be easily separated from the reaction media and handled visually. This combination is beneficial for the reuse of the catalyst and the purification of products. (2) Electrospun nanofibers containing nanocontainers offer the active agents inside the nanocontainers a double protection by both the fiber matrix and the nanocontainers. Since the polymer of the fibers and the polymer of the nanocontainers have usually opposite polarities, the encapsulated substance, for example, catalysts, dyes, or drugs, can be protected against a large variety of environmental influences. (3) Electrospun nanofibers exhibit unique advantages for tissue engineering and drug delivery that are a structural similarity to the extracellular matrix of biological tissues, large specific surface area, high and interconnected porosity which enhances cell adhesion, proliferation, drug loading, and mass transfer properties, as well as the flexibility in selecting the raw materials. Moreover, the nanocontainer-in-nanofiber structure allows multidrug loading and programmable release of each drug, which are very important to achieve synergistic effects in tissue engineering and disease therapy. The advantages offered by these materials encourage us to further understand the relationship between colloidal properties and fibers, to predict the morphology and properties of the fibers obtained by colloid-electrospinning, and to explore new possible combination of properties offered by nanoparticles and nanofibers.

A triblock terpolymer vs. blends of diblock copolymers for nanocapsules addressed by three independent stimuli

The chemical structure of triblock terpolymers is exploited to achieve polymer nanocapsules responsive to three different stimuli.

Nonaqueous Dispersion Formed by an Emulsion Solvent Evaporation Method Using Block-Random Copolymer Surfactant Synthesized by RAFT Polymerization

As surfactants for preparation of nonaqueous microcapsule dispersions by the emulsion solvent evaporation method, three copolymers composed of stearyl methacrylate (SMA) and glycidyl methacrylate (GMA) with different monomer sequences (i.e., random, block, and block-random) were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. Despite having the same comonomer composition, the copolymers exhibited different functionality as surfactants for creating emulsions with respective dispersed and continuous phases consisting of methanol and isoparaffin solvent. The optimal monomer sequence for the surfactant was determined based on the droplet sizes and the stabilities of the emulsions created using these copolymers. The block-random copolymer led to an emulsion with better stability than obtained using the random copolymer and a smaller droplet size than achieved with the block copolymer. Modification of the epoxy group of the GMA unit by diethanolamine (DEA) further decreased the droplet size, leading to higher stability of the emulsion. The DEA-modified block-random copolymer gave rise to nonaqueous microcapsule dispersions after evaporation of methanol from the emulsions containing colored dyes in their dispersed phases. These dispersions exhibited high stability, and the particle sizes were small enough for application to the inkjet printing process.

Double Redox-Responsive Release of Encoded and Encapsulated Molecules from Patchy Nanocapsules

Redox-responsive nanocapsules with surface regularities are presented. Two functional molecules are loaded in the nanocapsules. One molecule is chemically encoded in the capsule shell via a disulfide bond while the other one is physically entrapped in the capsule core. External reducing trigger can induce cascade release of the two payloads.

Advanced stimuli-responsive polymer nanocapsules with enhanced capabilities for payloads delivery

Recent progress in the design, preparation, and application of stimuli-responsive polymer nanocapsules with enhanced capabilities for payloads delivery are reviewed.

Nanoparticles from renewable polymers

The use of polymers from natural resources can bring many benefits for novel polymeric nanoparticle systems. Such polymers have a variety of beneficial properties such as biodegradability and biocompatibility, they are readily available on large scale and at low cost. As the amount of fossil fuels decrease, their application becomes more interesting even if characterization is in many cases more challenging due to structural complexity, either by broad distribution of their molecular weights (polysaccharides, polyesters, lignin) or by complex structure (proteins, lignin). This review summarizes different sources and methods for the preparation of biopolymer-based nanoparticle systems for various applications.