UV light stimulated encapsulation and release by polyelectrolyte microcapsules

NIR-responsive magnesium phosphate cement loaded with simvastatin-nanoparticles with biocompatibility and osteogenesis ability

The insufficient osteogenesis of magnesium phosphate cement (MPC) limits its biomedical application. It is of great significance to develop a bioactive MPC with osteogenic performance. In this study, an injectable MPC was reinforced by the incorporation of a near infrared (NIR)-responsive nanocontainer, which was based on simvastatin (SIM)-loaded mesoporous silica nanoparticles (MSNs) modified with a polydopamine (PDA) bilayer, named SMP. In addition, chitosan (CHI) was introduced into MPC (K-struvite) to enhance its mechanical properties and cytocompatibility. The results showed that nanocontainer-incorporated MPC possessed a prolonged setting time, almost neutral pH, excellent injectability, and enhanced compressive strength. Immersion tests indicated that SMP-CHI MPC could suppress rapid degradation. Based on its physicochemical features, the SMP-CHI MPC had good biocompatibility and osteogenesis properties, as shown via in vitro and in vivo experiments. These findings can provide a simple way to produce a multifunctional MPC with improved osteogenesis for further orthopedic applications.

NIR-responsive injectable magnesium phosphate bone cement loaded with icariin promotes osteogenesis

There were defects like limited osteogenesis and fast drug release in traditional magnesium phosphate bone cement (MPC). In this study, we loaded icariin in a mesoporous nano silica container modified by polydopamine and then added it and citric acid into MPC (IHP-CA MPCs). The results indicate that IHP-CA MPCs have a long curing time, almost neutral pH value, excellent injectability, and compressive strength. In vitro experiments have shown that IHP-CA MPCs have good biocompatibility and bone promoting ability. These improvements provide feasible solutions and references for the clinical application of MPCs as implants.

A decade of developing applications exploiting the properties of polyelectrolyte multilayer capsules

Transferring the layer-by-layer (LbL) coating approach from planar surfaces to spherical templates and subsequently dissolving these templates leads to the fabrication of polyelectrolyte multilayer capsules. The versatility of the coatings of capsules and their flexibility upon bringing in virtually any material into the coatings has quickly drawn substantial attention. Here, we provide an overview of the main developments in this field, highlighting the trends in the last decade. In the beginning, various methods of encapsulation and release are discussed followed by a broad range of applications, which were developed and explored. We also outline the current trends, where the range of applications is continuing to grow, including addition of whole new and different application areas.

Smart Strategies for Precise Delivery of CRISPR/Cas9 in Genome Editing

The emergence of CRISPR/Cas technology has enabled scientists to precisely edit genomic DNA sequences. This approach can be used to modulate gene expression for the treatment of genetic disorders and incurable diseases such as cancer. This potent genome-editing tool is based on a single guide RNA (sgRNA) strand that recognizes the targeted DNA, plus a Cas nuclease protein for binding and processing the target. CRISPR/Cas has great potential for editing many genes in different types of cells and organisms both in vitro and in vivo. Despite these remarkable advances, the risk of off-target effects has hindered the translation of CRISPR/Cas technology into clinical applications. To overcome this hurdle, researchers have devised gene regulatory systems that can be controlled in a spatiotemporal manner, by designing special sgRNA, Cas, and CRISPR/Cas delivery vehicles that are responsive to different stimuli, such as temperature, light, magnetic fields, ultrasound (US), pH, redox, and enzymatic activity. These systems can even respond to dual or multiple stimuli simultaneously, thereby providing superior spatial and temporal control over CRISPR/Cas gene editing. Herein, we summarize the latest advances on smart sgRNA, Cas, and CRISPR/Cas nanocarriers, categorized according to their stimulus type (physical, chemical, or biological).

Single and Multiple Stimuli-Responsive Polymer Particles for Controlled Drug Delivery

Polymers that can change their properties in response to an external or internal stimulus have become an interesting platform for drug delivery systems. Polymeric nanoparticles can be used to decrease the toxicity of drugs, improve the circulation of hydrophobic drugs, and increase a drug’s efficacy. Furthermore, polymers that are sensitive to specific stimuli can be used to achieve controlled release of drugs into specific areas of the body. This review discusses the different stimuli that can be used for controlled drug delivery based on internal and external stimuli. Internal stimuli have been defined as events that evoke changes in different characteristics, inside the body, such as changes in pH, redox potential, and temperature. External stimuli have been defined as the use of an external source such as light and ultrasound to implement such changes. Special attention has been paid to the particular chemical structures that need to be incorporated into polymers to achieve the desired stimuli response. A current trend in this field is the incorporation of several stimuli in a single polymer to achieve higher specificity. Therefore, to access the most recent advances in stimuli-responsive polymers, the focus of this review is to combine several stimuli. The combination of different stimuli is discussed along with the chemical structures that can produce it.

Biocompatible, photo-responsive layer-by-layer polymer nanocapsules with an oil core: in vitro and in vivo study

In cancer therapy, stimulus-responsive drug delivery systems are of particular interest for reducing side effects in healthy tissues and improving drug selectivity in the tumoral ones. Here, a strategy for the preparation of a photo-responsive cross-linked trilayer deposited onto an oil-in-water nanoemulsion via a layer-by-layer technique is reported. The system is made of completely biocompatible materials such as soybean oil, egg lecithin and glycol chitosan, with heparin as the polymeric shell. The oil core is pre-loaded with curcumin as a model lipophilic active molecule with anti-tumoral properties. The trilayer cross-linkage is performed via a photoinitiator-free thiol-ene 'click' reaction. In particular, the system is implemented with an o-nitrobenzyl group functionalized with a thiol moiety which can perform both the thiol-ene 'click' reaction and the cleavage meant for controlled drug release at two different wavelengths, respectively. So the preparation and characterization of a photo-responsive natural nanocarrier (PNC) that is stable under physiological conditions owing to the thiol-ene cross-linkage are reported. PNC performance has been assessed in vitro on melanoma cells as well as in vivo on xenograft tumour-induced mice.

Polyelectrolyte Multilayered Capsules as Biomedical Tools

Polyelectrolyte multilayered capsules (PEMUCs) obtained using the Layer-by-Layer (LbL) method have become powerful tools for different biomedical applications, which include drug delivery, theranosis or biosensing. However, the exploitation of PEMUCs in the biomedical field requires a deep understanding of the most fundamental bases underlying their assembly processes, and the control of their properties to fabricate novel materials with optimized ability for specific targeting and therapeutic capacity. This review presents an updated perspective on the multiple avenues opened for the application of PEMUCs to the biomedical field, aiming to highlight some of the most important advantages offered by the LbL method for the fabrication of platforms for their use in the detection and treatment of different diseases.

Immuno-affinitive supramolecular magnetic nanoparticles incorporating cucurbit[8]uril-mediated ternary host-guest complexation structures for high-efficient small extracellular vesicle enrichment

Enriching small extracellular vesicles (sEVs) with undamaged structure and function is a pivotal step for further applications in biological and clinical fields. It has prompted researchers to explore a carrier material that can efficiently capture sEVs while also gently release the captured sEVs. Here, 1-adamantylamine (1-ADA) responsive immuno-affinitive supramolecular magnetic nanoparticles (ISM-NPs) incorporating ternary host-guest complexation structures mediated by CB[8] were proposed to achieved the goal. In particular, the ternary host-guest complexation was constructed by the host molecule (cucurbit[8]uril, CB[8]) mediated assembly of two guest molecules (naphthol and bipyridine), and served as a cleavable bridge to connect the magnetic core and peripheral antibody. These constructed ISM-NPs performed well in the applications of capturing sEVs with a high capture efficiency of 85.5%. Further, the CB[8]-mediated ternary host-guest complexation structures can be disassembled with addition of the 1-ADA. Thus, the sEVs recognized by the anti-CD63 were released competitively, with a decent release efficiency more than 82%. The released sEVs kept intact morphology and exhibited appropriate size distribution and concentration. This supramolecular magnetic system, with 1-ADA responsive ternary host-guest complexation structures, may contribute to efficient enrichment of any other biomarkers, likely cells, proteins, peptides, etc.

Alginate-azo/chitosan nanocapsules in vitro drug delivery for hepatic carcinoma cells: UV-stimulated decomposition and drug release based on trans-to-cis isomerization

In this study, a nanocapsule (AL-azo/CH) was prepared with the anionic alginate-azo (AL-azo) and cationic chitosan (CH) via layer-by-layer method. Doxorubicin hydrochloride (DOX), an anticancer drug, was entrapped inside the AL-azo nanocapsules to form the DOX-loaded nanocapsules (DOX/AL-azo/CH). When the DOX/AL-azo/CH nanocapsules were irradiated with 365-nm light, the electrostatic attraction between the layers would be weakened as the trans-to-cis isomerization of AL-azo, which would lead to the UV-responsive decomposition and drug-release. Furthermore, cellular experiments showed that DOX/AL-azo/CH nanocapsules could be endocytosed by the HepG2 cells, and the confocal laser scanning microscope images showed that the DOX fluorescence intensity became stronger with the prolonging of irradiation time, indicating that the intracellular DOX-release could be controlled by UV irradiation. The AL-azo/CH nanocarriers were UV-triggered decomposition and drug-release, which stepped further towards the next-generation of nano-therapeutics with spatial and temporal external control in the field of polysaccharide.

Azo modified hyaluronic acid based nanocapsules: CD44 targeted, UV-responsive decomposition and drug release in liver cancer cells

Herein, we demonstrate a novel UV-induced decomposable nanocapsule of natural polysaccharide (HA-azo/PDADMAC). The nanocapsules are fabricated based on layer-by-layer co-assembly of anionic azobenzene functionalized hyaluronic acid (HA-azo) and cationic poly diallyl dimethylammonium chloride (PDADMAC). When the nanocapsules are exposed to 365 nm light, ultraviolet photons can trigger the photo-isomerization of azobenzene groups in the framework. The nanocapsules could decompose from large-sized nanocapsules to small fragments. Due to their optimized original size (~180 nm), the nanocapsules can effectively avoid biological barriers, provide a long blood circulation and achieve high tumor accumulation. It can fast eliminate nanocapsules from tumor and release the loaded drugs for chemotherapy after UV-induced dissociation. Besides, HA is an endogenous polysaccharide that shows intrinsic targetability to CD44 receptors on surface of cancer cells. The intracellular experiment shows that the HA-azo/PDADMAC nanocapsules with CD44 targeting ability and UV-controlled intracellular drug release are promising for cancer chemotherapy.

Current Advances in Black Phosphorus-Based Drug Delivery Systems for Cancer Therapy

Cancer has been one of the major threats to the lives of human beings for centuries. Traditional therapy is more or less faced with certain defects, such as poor targeting, easy degradation, high side effects, etc. Therefore, in order to improve the treatment efficiency of drugs, an intelligent drug delivery system (DDS) is considered as a promising solution strategy. Due to their special structure and large specific surface area, 2D materials are considered to be a good platform for drug delivery. Black phosphorus (BP), as a new star of the 2D family, is recommended to have the potential to construct DDS by virtue of its outstanding photothermal therapy (PTT), photodynamic therapy (PDT), and biodegradable properties. This tutorial review is intended to provide an introduction of the current advances in BP-based DDSs for cancer therapy, which covers topics from its construction, classified by the types of platforms, to the stimuli-responsive controlled drug release. Moreover, their cancer therapy applications including mono-, bi-, and multi-modal synergistic cancer therapy as well as the research of biocompatibility are also discussed. Finally, the current status and future prospects of BP-based DDSs for cancer therapy are summarized.

A closer physico-chemical look to the Layer-by-Layer electrostatic self-assembly of polyelectrolyte multilayers

The fabrication of polyelectrolyte multilayer films (PEMs) using the Layer-by-Layer (LbL) method is one of the most versatile approaches for manufacturing functional surfaces. This is the result of the possibility to control the assembly process of the LbL films almost at will, by changing the nature of the assembled materials (building blocks), the assembly conditions (pH, ionic strength, temperature, etc.) or even by changing some other operational parameters which may impact in the structure and physico-chemical properties of the obtained multi-layered films. Therefore, the understanding of the impact of the above mentioned parameters on the assembly process of LbL materials plays a critical role in the potential use of the LbL method for the fabrication of new functional materials with technological interest. This review tries to provide a broad physico-chemical perspective to the study of the fabrication process of PEMs by the LbL method, which allows one to take advantage of the many possibilities offered for this approach on the fabrication of new functional nanomaterials.

Direction-Specific Release from Capsules with Homogeneous or Janus Shells Using an Ultrasound Approach

A variety of approaches have been developed to release contents from capsules, including techniques that use electric or magnetic fields, light, or ultrasound as a stimulus. However, in the majority of the known approaches, capsules are disintegrated in violent way and the liberation of the encapsulated material is often in a random direction. Thus, the controllable and direction-specific release from microcapsules in a simple and effective way is still a great challenge. This greatly limits the use of microcapsules in applications where targeted and directional release is desirable. Here, we present a convenient ultrasonic method for controllable and unidirectional release of an encapsulated substance. The release is achieved by using MHz-frequency ultrasound that enables the inner liquid stretching, which imposes mechanical stress on the capsule's shell. This leads to the puncturing of the shell and enables smooth liberation of the liquid payload in one direction. We demonstrate that 1-4.3 MHz acoustic waves with the intensity of a few W/cm² are capable of puncturing of particle capsules with diameters ranging from around 300 μm to 5 mm and the release of the encapsulated liquid in a controlled manner. Various aspects of our route, including the role of the capsule size, ultrasound wavelength, and intensity in the performance of the method, are studied in detail. We also show that the additional control of the release can be achieved by using capsules having patchy shells. The presented method can be used to facilitate chemical reactions in micro- and nanolitre droplets and various small-scale laboratory operations carried in bulk liquids in microenvironment. Our results may also serve as an entry point for testing other uses of the method and formulation of theoretical modeling of the presented ultrasound mechanism.

Multilayer capsules made of weak polyelectrolytes: a review on the preparation, functionalization and applications in drug delivery

Multilayer capsules have been of great interest for scientists and medical communities in multidisciplinary fields of research, such as drug delivery, sensing, biomedicine, theranostics and gene therapy. The most essential attributes of a drug delivery system are considered to be multi-functionality and stimuli responsiveness against a range of external and internal stimuli. Apart from the highly explored strong polyelectrolytes, weak polyelectrolytes offer great versatility with a highly controllable architecture, unique stimuli responsiveness and easy tuning of the properties for intracellular delivery of cargo. This review describes the progress in the preparation, functionalization and applications of capsules made of weak polyelectrolytes or their combination with biopolymers. The selection of a sacrificial template for capsule formation, the driving forces involved, the encapsulation of a variety of cargo and release based on different internal and external stimuli have also been addressed. We describe recent perspectives and obstacles of weak polyelectrolyte/biopolymer systems in applications such as therapeutics, biosensing, bioimaging, bioreactors, vaccination, tissue engineering and gene delivery. This review gives an emerging outlook on the advantages and unique responsiveness of weak polyelectrolyte based systems that can enable their widespread use in potential applications.

Bioinspired Smart Nanosystems in Advanced Therapeutic Applications

BACKGROUND

Nanoparticle technologies used for human administration must be designed to interact with a living host environment. The idea about bioinspired smart drug delivery carriers includes the development of biocompatible nanomaterials which can be further loaded with the drug for specific targeted drug delivery applications.

OBJECTIVE

Biosmart nanosystems are used for several applications in the delivery of drugs and pharmaceuticals for their therapeutic applications like biological markers, diagnostic purposes such as imaging applications and also for gene therapy. Thus, the bioinspired nanocarriers are capable of carrying biologically active molecules to the target sites. This bioinspired nanosystem constitutes of lipids, polymers and biomaterials which utilizes various responsive sensors for targeted drug delivery systems. However, external conditions such as heat, light, magnetic or electric field and ultrasounds, along with temperature, altered pH and ionic strength can affect the bioinspired smart nanosystem for drug delivery.

CONCLUSION

The present review focuses on challenges for the development of bioinspired smart nanocarriers for the management of various disorders.

Engineering Nanoparticles for Targeted Delivery of Nucleic Acid Therapeutics in Tumor

In the past 10 years, with the increase of investment in clinical nano-gene therapy, there are many trials that have been discontinued due to poor efficacy and serious side effects. Therefore, it is particularly important to design a suitable gene delivery system. In this paper, we introduce the application of liposomes, polymers, and inorganics in gene delivery; also, different modifications with some stimuli-responsive systems can effectively improve the efficiency of gene delivery and reduce cytotoxicity and other side effects. Besides, the co-delivery of chemotherapy drugs with a drug tolerance-related gene or oncogene provides a better theoretical basis for clinical cancer gene therapy.

Physically-triggered nanosystems based on two-dimensional materials for cancer theranostics

There is an increasing demand to develop effective methods for treating malignant diseases to improve healthcare in our society. Stimuli-responsive nanosystems, which can respond to internal or external stimuli are promising in cancer therapy and diagnosis due to their functionality and versatility. As a newly emerging class of nanomaterials, two-dimensional (2D) nanomaterials have attracted huge interest in many different fields including biomedicine due to their unique physical and chemical properties. In the past decade, stimuli-responsive nanosystems based on 2D nanomaterials have been widely studied, showing promising applications in cancer therapy and diagnosis, including phototherapies, magnetic therapy, drug and gene delivery, and non-invasive imaging. Here, we will focus our attention on the state-of-the-art of physically-triggered nanosystems based on graphene and two-dimensional nanomaterials for cancer therapy and diagnosis. The physical triggers include light, temperature, magnetic and electric fields.

Comparison of two encapsulation systems of UV stabilizers on the UV protection efficiency of wood clear coats

One of the major issues in the wood industry is the durability of clear coatings. The addition of organic ultraviolet absorbers (UVAs) improves coating resistance by the absorption and conversion of UV radiation into harmless heat. Organic UVAs are, however, easily degraded by free radicals produced by photodegradation inside the polymer matrix and are prone to migration in the coating. In this study, commercial UVAs and hindered amine light stabilizers (HALS) entrapped into poly(methyl methacrylate) (PMMA) microspheres and CaCO3 templates coated with UV-responsive polymers were added into clear acrylic water-based coating formulation. Artificial accelerated weathering experiments were performed on each formulation. Raman spectroscopy mapping was performed to visualize the concentration and distribution of UVAs and HALS. This study also presents a comparison of the mechanical properties of coatings obtained by dynamic mechanical analysis. Results showed that coating mechanical properties were improved when using encapsulated UVAs and HALS inside PMMA microspheres. The color change of the wood and coating system was minimized and the production of photo-oxidation compounds in the binder was also limited.

Tunable Interfacial Properties in Silk Ionomer Microcapsules with Tailored Multilayer Interactions

Microencapsulation techniques represent a critical step in realizing highly controlled transport of functional materials in multiphase systems. The first demonstration of microcapsules prepared from minimally grafted silk ionomers (silk fibroin modified with cationic/anionic charge groups) are presented here. These tailored biomacromolecules have shown significantly increased biocompatibility over traditional polyelectrolytes and heavily grafted silk ionomers, but the low grafting density had previously limited attempts to fabricate stable microcapsules. In addition, the first microcapsules from polyethylene-glycol-grafted silk ionomers are fabricated and the corresponding impact on microcapsule behavior is demonstrated. The materials are shown to exhibit pH-responsive properties, with the microcapsules demonstrating an approx. tenfold decrease in stiffness and an approx. threefold change in diffusion coefficient when moving from acidic to basic buffer. Finally, the effect of assembly conditions of the microcapsules are shown to play a large role in determining final properties, with microcapsules prepared in acidic buffers showing lower roughness, stiffness, and an inversion in transport behavior (i.e., permeability decreases at higher pH).

Near-infrared light triggered drug release from mesoporous silica nanoparticles

Stimuli triggered drug delivery systems enable controlled release of drugs at the optimal space and time, thus achieving optimal therapeutic effects. As one of the most important stimuli used in bioapplications, near-infrared (NIR) light possesses unique advantages such as deep tissue penetration with minimum auto-fluorescence & tissue scattering and high biosafety. Mesoporous silica nanoparticles (MSNs) are one of the most studied nanocarriers; apart from having a high surface area and large pore volume for loading of drugs, they can be easily functionalized with inorganic nanomaterials and stimuli responsive polymers or organic switch molecules, creating possibilities for designing complex stimuli triggered drug delivery systems. Considering the high tissue penetration depth of NIR light and the unique mesoporous structure of MSNs, NIR responsive inorganic nanoparticle functionalized MSNs can be further combined with stimuli responsive materials to form smart "nano-devices" for controlled drug delivery toward tumors, and to date much progress has been made. In this article, recent advances in the design of NIR triggered mesoporous silica drug delivery systems are systematically summarized and some outstanding studies are highlighted. We will also discuss the shortcomings, challenges and opportunities in the field.

Near-Infrared Triggered Decomposition of Nanocapsules with High Tumor Accumulation and Stimuli Responsive Fast Elimination

A near-infrared (NIR) induced decomposable polymer nanocapsule is demonstrated. The nanocapsules are fabricated based on layer-by-layer co-assembly of azobenzene functionalized polymers and up/downconversion nanoparticles (U/DCNPs). When the nanocapsules are exposed to 980 nm light, ultraviolet/visible photons emitted by the U/DCNPs can trigger the photoisomerization of azobenzene groups in the framework. The nanocapsules could decompose from large-sized nanocapsule to small U/DCNPs. Owing to their optimized original size (ca. 180 nm), the nanocapsules can effectively avoid biological barriers, provide a long blood circulation (ca. 5 h, half-life time) and achieve four-fold tumor accumulation. It can fast eliminate from tumor within one hour and release the loaded drugs for chemotherapy after NIR-induced dissociation from initial 180 nm capsules to small 20 nm U/DCNPs.

Bioreducible nanocapsules for folic acid-assisted targeting and effective tumor-specific chemotherapy

INTRODUCTION

Increasing demands in precise control over delivery and functionalization of therapeutic agents for tumor-specific chemotherapy have led to a rapid development in nanocarriers. Herein, we report a nanocapsule (NC) system for tumor-oriented drug delivery and effective tumor therapy.

MATERIALS AND METHODS

Functionalized hyaluronan is utilized to build up the NC shells, in which bioreduction cleavable sites, targeting ligand folic acid (FA), and zwitterionic tentacles are integrated.

RESULTS

The hollow NCs obtained (~50 nm in diameter) showed well-defined spherical shell structures with a shell thickness of ~8 nm. These specially designed NCs (doxorubicin [DOX]/FA-Z-NCs) with high drug encapsulation content exhibited good biocompatibility in vitro and fast intracellular drug release behavior mediated by intracellular glutathione.

CONCLUSION

Cellular uptake tests demonstrated rapid uptake of these functionalized NCs and effective escape from endosomes. Antitumor efficacy of the DOX/FA-Z-NCs was confirmed by the significant tumor growth inhibition effect as well as greatly reduced side effects, in contrast with those of the free drug DOX hydrochloride.

Layer-by-Layer polyelectrolyte assemblies for encapsulation and release of active compounds

Soft assemblies obtained following the Layer-by-Layer (LbL) approach are accounted among the most interesting systems for designing biomaterials and drug delivery platforms. This is due to the extraordinary versatility and flexibility offered by the LbL method, allowing for the fabrication of supramolecular multifunctional materials using a wide range of building blocks through different types of interactions (electrostatic, hydrogen bonds, acid-base or coordination interactions, or even covalent bonds). This provides the bases for the building of materials with different sizes, shapes, compositions and morphologies, gathering important possibilities for tuning and controlling the physico-chemical properties of the assembled materials with precision in the nanometer scale, and consequently creating important perspective for the application of these multifunctional materials as cargo systems in many areas of technological interest. This review studies different physico - chemical aspects associated with the assembly of supramolecular materials by the LbL method, paying special attention to the description of these aspects playing a central role in the application of these materials as cargo platforms for encapsulation and release of active compounds.

The interaction of clozapine loaded nanocapsules with the hCMEC/D3 cells - In vitro model of blood brain barrier

Despite progress in the development of novel pharmacological compounds, their efficacy in the treatment of neuropathologies is not satisfactory. One strategy to achieve safe and efficient brain targeting therapy is to design nanocarriers capable of transporting antipsychotic drugs through the BBB (without affecting the normal functions of the barrier) in a defined part of the brain. Here we investigate the interaction of clozapine-loaded polymeric Nano capsules (CLO-NCs) with hCMEC/D3 (human cerebral microvascular endothelial cells, D3 clone) cells that constitutes an in vitro model of the blood brain barrier (BBB). CLO-NCs (average size of 100nm) were constructed by the technique of sequential adsorption of polyelectrolytes (LbL), using biocompatible polyanion PGA (Poly-l-glutamic acid sodium salt) and polycation PLL (poly L-lysine) on clozapine-loaded nano-emulsion cores. Pegylated external layers were prepared using PGA-g(39)-PEG (PGA grafted by PEG poly(ethylene glycol)). The influence of the physicochemical properties of the CLO-NCs (charge, size, surface modification) on cell viability was determined. Advanced studies of CLO-NCs internalization (including endocytosis and transcytosis experiments) using confocal microscopy, flow cytometry and fluorescence spectroscopy are presented. Our results indicate that among the studied NCs, the pegylated clozapine-loaded NCs were the most protected from their uptake by macrophages, and they were the least toxic to hCMEC/D3 cells. They were also the most efficient in the transcytosis experiment, which serves as an indicator of their ability to cross a model BBB.

Dual cellular stimuli-responsive hydrogel nanocapsules for delivery of anticancer drugs

In this work, we report dual cellular environmental stimuli-responsive hydrogel nanocapsules (HA-NCs) for delivery of an anticancer drug (doxorubicin, DOX). This nanocapsule drug delivery system was specially designed to be triggered by stimuli in intra-cellular environments, specifically high glutathione (GSH) concentration and low pH. Biocompatible hyaluronan was used as the basic nanocapsule shell building material. Chemical modifications were conducted in order to functionalize it; specifically, GSH cleavable crosslinking sites and pH responsive expansion sites were introduced. After passive delivery to tumor sites via an enhanced permeation and retention (EPR) effect and cellular uptake, the nanocapsule shells underwent a swelling/disassembly process due to high GSH concentration (e.g., 10 mM), which induced cleavage of disulfide (S-S) bonds, and low pH (e.g., pH 5), which caused water influx associated with deprotection of the acetal groups. This process enabled rupture of the hydrogel nanocapsules and therefore resulted in release of the encapsulated payloads. This hydrogel nanocapsule system exhibited a great ability to release the vast majority of the encapsulated DOX in tumor cells, as proven by the remarkably (4.7-fold) accelerated drug release rate within tumor cells (pH 5.0, GSH 10 mM), in sharp contrast to the drug release rate under physiological conditions (pH 7.4, GSH 0). In vitro bio-evaluation showed the good biocompatibility of the nanocapsule carriers and their efficient cancer cell growth inhibition activity after drug encapsulation. In vivo studies confirmed that the DOX containing nanocapsules (DOX/HA-NCs) had comparable antitumor efficiency and greatly reduced side effects as compared with free DOX (DOX·HCl).

Cucurbit[8]uril-Containing Multilayer Films for the Photocontrolled Binding and Release of a Guest Molecule

The powerful host-guest chemistry of cucurbit[8]uril (CB[8]) was employed to obtain photoresponsive polyelectrolyte multilayer films for the reversible and photocontrolled binding and release of an organic guest molecule. For this purpose, we designed and synthesized a polyelectrolyte with azobenzene side groups. Then, CB[8] was associated with the azo side group to obtain a supramolecular host-guest complex that was further used as building block in order to prepare photoresponsive and CB[8]-containing polyelectrolyte multilayer films. Ultraviolet spectroscopy and a dissipative quartz crystal microbalance are employed to monitor the formation of the host-guest complex and the layer-by-layer self-assembly of the multilayer films, respectively. We demonstrate that the photoresponsive properties of the azo side groups are maintained before and after host-guest complexation with CB[8] in solution and within the multilayer films, respectively. A guest molecule was then specifically included as second binding partner into the CB[8]-containing multilayer films. Subsequently, the release of the guest was performed by UV light irradiation due to the trans-cis isomerization of the adjacent azo side groups. Re-isomerization of the azo side groups was achieved by VIS light irradiation and enabled the rebinding of the guest into CB[8]. Finally, we demonstrate that the photocontrolled binding and release within CB[8]-containing multilayer films can reliably and reversibly be performed over a period of more than 2 weeks with constant binding efficiency. Therefore, we expect such novel type of photosensitive films to have promising future applications in the field of stimuli-responsive nanomaterials.

Smart micro/nanoparticles in stimulus-responsive drug/gene delivery systems

New achievements in the realm of nanoscience and innovative techniques of nanomedicine have moved micro/nanoparticles (MNPs) to the point of becoming actually useful for practical applications in the near future. Various differences between the extracellular and intracellular environments of cancerous and normal cells and the particular characteristics of tumors such as physicochemical properties, neovasculature, elasticity, surface electrical charge, and pH have motivated the design and fabrication of inventive "smart" MNPs for stimulus-responsive controlled drug release. These novel MNPs can be tailored to be responsive to pH variations, redox potential, enzymatic activation, thermal gradients, magnetic fields, light, and ultrasound (US), or can even be responsive to dual or multi-combinations of different stimuli. This unparalleled capability has increased their importance as site-specific controlled drug delivery systems (DDSs) and has encouraged their rapid development in recent years. An in-depth understanding of the underlying mechanisms of these DDS approaches is expected to further contribute to this groundbreaking field of nanomedicine. Smart nanocarriers in the form of MNPs that can be triggered by internal or external stimulus are summarized and discussed in the present review, including pH-sensitive peptides and polymers, redox-responsive micelles and nanogels, thermo- or magnetic-responsive nanoparticles (NPs), mechanical- or electrical-responsive MNPs, light or ultrasound-sensitive particles, and multi-responsive MNPs including dual stimuli-sensitive nanosheets of graphene. This review highlights the recent advances of smart MNPs categorized according to their activation stimulus (physical, chemical, or biological) and looks forward to future pharmaceutical applications.

Light responsive multilayer surfaces with controlled spatial extinction capability

Multilayer systems obtained using the Layer-by-Layer (LbL) technology have been proposed for a variety of biomedical applications in tissue engineering and regenerative medicine. LbL assembly is a simple and highly versatile method to modify surfaces and fabricate robust and highly-ordered nanostructured coatings over almost any type of substrates and with a wide range of substances. The incorporation of polyoxometalate (POM) inorganic salts as constituents of the layers presents a possibility of promoting light-stimuli responses in LbL substrates. We propose the design of a biocompatible photo-responsive multilayer system based on a Preyssler-type POM ([NaP₅W₃₀O₁₁₀]^14-) and a natural origin polymer, chitosan, using the LbL methodology. The photo-reduction properties of the POM allow the spatially controlled disruption of the assembled layers due to the weakening of the electrostatic interactions between the layers. This system has found applicability in detaching devices, such as the cell sheet technology, which may solve the drawbacks actually found in other cell treatment proposals.

Osmo-solidification of all-aqueous emulsion with enhanced preservation of protein activity

An “osmo-solidification” approach that solidifies all-aqueous emulsion droplets for encapsulating proteins with superior preservation of their activity.

Impact of high-frequency ultrasound on nanocomposite microcapsules: in silico and in situ visualization

Simulation and direct visualization of high-frequency (1.2 MHz) ultrasound impact on microcapsules with ZnO nanoparticles embedded in the shell.

Preparation of alginate-chitosan fibers with potential biomedical applications

The preparation of alginate-chitosan fibers, through wet spinning technique, as well as the study of their properties as a function of chitosan's molecular weight and retention time in the coagulation bath, is presented and discussed in this work. Scanning electron microscopy (SEM) revealed that the fibers presented irregular and rough surfaces, with a grooved and heavily striated morphology distributed throughout the structure. Dynamic mechanical analysis (DMA) showed that, with the exception of elongation at break, the incorporation of chitosan into the fibers improved their tensile properties. The in vitro release profile of sulfathiazole as a function of chitosan's molecular weight indicated that the fibers are viable carriers of drugs. Kinetic models showed that the release of the model drug is first-order, and the release mechanism is governed by the Korsmeyer-Peppas model. Likewise, fibers loaded with sulfathiazole showed excellent inhibition of Escherichia coli growth after an incubation time of 24h at 37 °C.

Controlled release of encapsulated bioactive volatiles by rupture of the capsule wall through the light-induced generation of a gas

The encapsulation of photolabile 2-oxoacetates in core-shell microcapsules allows the light-induced, controlled release of bioactive compounds. On irradiation with UVA light these compounds degrade to generate an overpressure of gas inside the capsules, which expands or breaks the capsule wall. Headspace measurements confirmed the light-induced formation of CO and CO2 and the successful release of the bioactive compound, while optical microscopy demonstrated the formation of gas bubbles, the cleavage of the capsule wall, and the leakage of the oil phase out of the capsule. The efficiency of the delivery system depends on the structure of the 2-oxoacetate, the quantity used with respect to the thickness of the capsule wall, and the intensity of the irradiating UVA light.

“Old” chemistry in a new context: photocleavable 2-oxoacetate-containing latex dispersions and core–shell microcapsules for the controlled release of volatile compounds

2-Oxoacetates polymerised into nanoparticles or encapsulated in microcapsules are stable against hydrolysis and release fragrances on UVA irradiation.

Pharmacological aspects of release from microcapsules - from polymeric multilayers to lipid membranes

This review is devoted to pharmacological applications of principles of release from capsules to overcome the membrane barrier. Many of these principles were developed in the context of polymeric multilayer capsule membrane modulation, but they are also pertinent to liposomes, polymersomes, capsosomes, particles, emulsion-based carriers and other carriers. We look at these methods from the physical, chemical or biological driving mechanisms point of view. In addition to applicability for carriers in drug delivery, these release methods are significant for another area directly related to pharmacology - modulation of the permeability of the membranes and thus promoting the action of drugs. Emerging technologies, including ionic current monitoring through a lipid membrane on a nanopore, are also highlighted.

Biological applications of LbL multilayer capsules: from drug delivery to sensing

Polyelectrolyte multilayer (PEM) capsules engineered with active elements for targeting, labeling, sensing and delivery hold great promise for the controlled delivery of drugs and the development of new sensing platforms. PEM capsules composed of biodegradable polyelectrolytes are fabricated for intracellular delivery of encapsulated cargo (for example peptides, enzymes, DNA, and drugs) through gradual biodegradation of the shell components. PEM capsules with shells responsive to environmental or physical stimuli are exploited to control drug release. In the presence of appropriate triggers (e.g., pH variation or light irradiation) the pores of the multilayer shell are unlocked, leading to the controlled release of encapsulated cargos. By loading sensing elements in the capsules interior, PEM capsules sensitive to biological analytes, such as ions and metabolites, are assembled and used to detect analyte concentration changes in the surrounding environment. This Review aims to evaluate the current state of PEM capsules for drug delivery and sensing applications.