Polyglycerol-Functionalized ß-Cyclodextrins as Crosslinkers in Thermoresponsive Nanogels for the Enhanced Dermal Penetration of Hydrophobic Drugs.

Thermoresponsive nanogels (tNGs) are promising candidates for dermal drug delivery. However, poor incorporation of hydrophobic drugs into hydrophilic tNGs limits the therapeutic efficiency. To address this challenge, ß-cyclodextrins (ß-CD) are functionalized by hyperbranched polyglycerol serving as crosslinkers (hPG-ßCD) to fabricate ßCD-tNGs. This novel construct exhibits augmented encapsulation of hydrophobic drugs, shows the appropriate thermal response to dermal administration, and enhances the dermal penetration of payloads. The structural influences on the encapsulation capacity of ßCD-tNGs for hydrophobic drugs are analyzed, while concurrently retaining their efficacy as skin penetration enhancers. Various synthetic parameters are considered, encompassing the acrylation degree and molecular weight of hPG-ßCD, as well as the monomer composition of ßCD-tNGs. The outcome reveals that ßCD-tNGs substantially enhance the aqueous solubility of Nile Red elevating to 120 µg mL-1 and augmenting its dermal penetration up to 3.33 µg cm-2. Notably, the acrylation degree of hPG-ßCD plays a significant role in dermal drug penetration, primarily attributed to the impact on the rigidity and hydrophilicity of ßCD-tNGs. Taken together, the introduction of the functionalized ß-CD as the crosslinker in tNGs presents a novel avenue to enhance the efficacy of hydrophobic drugs in dermatological applications, thereby offering promising opportunities for boosted therapeutic outcomes.

Nanocarriers for Skin Applications: Where Do We Stand?

Skin penetration of active molecules for treatment of diverse diseases is a major field of research owing to the advantages associated with the skin like easy accessibility, reduced systemic-derived side effects, and increased therapeutic efficacy. Despite these advantages, dermal drug delivery is generally challenging due to the low skin permeability of therapeutics. Although various methods have been developed to improve skin penetration and permeation of therapeutics, they are usually aggressive and could lead to irreversible damage to the stratum corneum. Nanosized carrier systems represent an alternative approach for current technologies, with minimal damage to the natural barrier function of skin. In this Review, the use of nanoparticles to deliver drug molecules, genetic material, and vaccines into the skin is discussed. In addition, nanotoxicology studies and the recent clinical development of nanoparticles are highlighted to shed light on their potential to undergo market translation.

Design and Testing of Efficient Mucus-Penetrating Nanogels-Pitfalls of Preclinical Testing and Lessons Learned.

Mucosal surfaces pose a challenging environment for efficient drug delivery. Various delivery strategies such as nanoparticles have been employed so far; yet, still yielding limited success. To address the need of efficient transmucosal drug delivery, this report presents the synthesis of novel disulfide-containing dendritic polyglycerol (dPG)-based nanogels and their preclinical testing. A bifunctional disulfide-containing linker is coupled to dPG to act as a macromolecular crosslinker for poly-N-isopropylacrylamide (PNIPAM) and poly-N-isopropylmethacrylamide (PNIPMAM) in a precipitation polymerization process. A systematic analysis of the polymerization reveals the importance of a careful polymer choice to yield mucus-degradable nanogels with diameters between 100 and 200 nm, low polydispersity, and intact disulfide linkers. Absorption studies in porcine intestinal tissue and human bronchial epithelial models demonstrate that disulfide-containing nanogels are highly efficient in overcoming mucosal barriers. The nanogels efficiently degrade and deliver the anti-inflammatory biomacromolecule etanercept into epithelial tissues yielding local anti-inflammatory effects. Over the course of this work, several problems are encountered due to a limited availability of valid test systems for mucosal drug-delivery systems. Hence, this study also emphasizes how critical a combined and multifaceted approach is for the preclinical testing of mucosal drug-delivery systems, discusses potential pitfalls, and provides suggestions for solutions.

Environmental Liquid Cell Technique for Improved Electron Microscopic Imaging of Soft Matter in Solution.

Liquid-phase transmission electron microscopy is a technique for simultaneous imaging of the structure and dynamics of specimens in a liquid environment. The conventional sample geometry consists of a liquid layer tightly sandwiched between two Si3N4 windows with a nominal spacing on the order of 0.5 µm. We describe a variation of the conventional approach, wherein the Si3N4 windows are separated by a 10-µm-thick spacer, thus providing room for gas flow inside the liquid specimen enclosure. Adjusting the pressure and flow speed of humid air inside this environmental liquid cell (ELC) creates a stable liquid layer of controllable thickness on the bottom window, thus facilitating high-resolution observations of low mass-thickness contrast objects at low electron doses. We demonstrate controllable liquid thicknesses in the range 160 ± 34 to 340 ± 71 nm resulting in corresponding edge resolutions of 0.8 ± 0.06 to 1.7 ± 0.8 nm as measured for immersed gold nanoparticles. Liquid layer thickness 40 ± 8 nm allowed imaging of low-contrast polystyrene particles. Hydration effects in the ELC have been studied using poly-N-isopropylacrylamide nanogels with a silica core. Therefore, ELC can be a suitable tool for in situ investigations of liquid specimens.

A Dual Fluorescence-Spin Label Probe for Visualization and Quantification of Target Molecules in Tissue by Multiplexed FLIM-EPR Spectroscopy.

Simultaneous visualization and concentration quantification of molecules in biological tissue is an important though challenging goal. The advantages of fluorescence lifetime imaging microscopy (FLIM) for visualization, and electron paramagnetic resonance (EPR) spectroscopy for quantification are complementary. Their combination in a multiplexed approach promises a successful but ambitious strategy because of spin label-mediated fluorescence quenching. Here, we solved this problem and present the molecular design of a dual label (DL) compound comprising a highly fluorescent dye together with an EPR spin probe, which also renders the fluorescence lifetime to be concentration sensitive. The DL can easily be coupled to the biomolecule of choice, enabling in vivo and in vitro applications. This novel approach paves the way for elegant studies ranging from fundamental biological investigations to preclinical drug research, as shown in proof-of-principle penetration experiments in human skin ex vivo.

Reverting the molecular fingerprint of tumor dormancy as a therapeutic strategy for glioblastoma.

Glioblastoma is an aggressive and invasive brain malignancy with high mortality rates despite current treatment modalities. In this study, we show that a 7-gene signature, previously found to govern the switch of glioblastomas from dormancy to aggressive tumor growth, correlates with improved overall survival of patients with glioblastoma. Using glioblastoma dormancy models, we validated the role of 2 genes from the signature, thrombospondin-1 ( TSP-1) and epidermal growth factor receptor ( EGFR), as regulators of glioblastoma dormancy and explored their therapeutic potential. EGFR up-regulation was reversed using EGFR small interfering RNA polyplex, antibody, or small-molecule inhibitor. The diminished function of TSP-1 was augmented via a peptidomimetic. The combination of EGFR inhibition and TSP-1 restoration led to enhanced therapeutic efficacy in vitro, in 3-dimensional patient-derived spheroids, and in a subcutaneous human glioblastoma model in vivo. Systemic administration of the combination therapy to mice bearing intracranial murine glioblastoma resulted in marginal therapeutic outcomes, probably due to brain delivery challenges, p53 mutation status, and the aggressive nature of the selected cell line. Nevertheless, this study provides a proof of concept for exploiting regulators of tumor dormancy for glioblastoma therapy. This therapeutic strategy can be exploited for future investigations using a variety of therapeutic entities that manipulate the expression of dormancy-associated genes in glioblastoma as well as in other cancer types.-Tiram, G., Ferber, S., Ofek, P., Eldar-Boock, A., Ben-Shushan, D., Yeini, E., Krivitsky, A., Blatt, R., Almog, N., Henkin, J., Amsalem, O., Yavin, E., Cohen, G., Lazarovici, P., Lee, J. S., Ruppin, E., Milyavsky, M., Grossman, R., Ram, Z., Calderón, M., Haag, R., Satchi-Fainaro, R. Reverting the molecular fingerprint of tumor dormancy as a therapeutic strategy for glioblastoma.

The influence of the shape of Au nanoparticles on the catalytic current of fructose dehydrogenase.

Graphite electrodes were modified with triangular (AuNTrs) or spherical (AuNPs) nanoparticles and further modified with fructose dehydrogenase (FDH). The present study reports the effect of the shape of these nanoparticles (NPs) on the catalytic current of immobilized FDH pointing out the different contributions on the mass transfer-limited and kinetically limited currents. The influence of the shape of the NPs on the mass transfer-limited and the kinetically limited current has been proved by using two different methods: a rotating disk electrode (RDE) and an electrode mounted in a wall jet flow-through electrochemical cell attached to a flow system. The advantages of using the wall jet flow system compared with the RDE system for kinetic investigations are as follows: no need to account for substrate consumption, especially in the case of desorption of enzyme, and studies of product-inhibited enzymes. The comparison reveals that virtually identical results can be obtained using either of the two techniques. The heterogeneous electron transfer (ET) rate constants (kS) were found to be 3.8 ± 0.3 s-1 and 0.9 ± 0.1 s-1, for triangular and spherical NPs, respectively. The improvement observed for the electrode modified with AuNTrs suggests a more effective enzyme-NP interaction, which can allocate a higher number of enzyme molecules on the electrode surface. Graphical abstract The shape of gold nanoparticles has a crucial effect on the catalytic current related to the oxidation of D-(-)-fructose to 5-keto-D-(-)-fructose occurring at the FDH-modified electrode surface. In particular, AuNTrs have a higher effect compared with the spherical one.

Effect of Delivery Platforms Structure on the Epidermal Antigen Transport for Topical Vaccination.

Transdermal immunization is highly attractive because of the skin's accessibility and unique immunological characteristics. However, it remains a relatively unexplored route of administration because of the great difficulty of transporting antigens past the outermost layer of skin, the stratum corneum. In this article, the abilities of three poly( N-vinylcaprolactam) (PVCL)-based thermoresponsive assemblies-PVCL hydrogels and nanogels plus novel film forming PVCL/acrylic nanogels-to act as protein delivery systems were investigated. Similar thermal responses were observed in all systems, with transition temperatures close to 32 °C, close to that of the skin surface. The investigated dermal delivery systems showed no evidence of cytotoxicity in human fibroblasts and were able to load and release ovalbumin (OVA), a well-studied antigen, in a temperature-dependent manner in vitro. The penetration of OVA into ex vivo human skin following topical application was evaluated, where enhanced skin delivery was seen for the OVA-loaded PVCL systems relative to administration of the protein alone. The distinct protein release and skin penetration profiles observed for the different PVCL assemblies were here discussed on the basis of their structural differences.

PEGylated dendritic polyglycerol conjugate targeting NCAM-expressing neuroblastoma: Limitations and challenges.

Neural cell adhesion molecule (NCAM) is found to be a stem-cell marker in several tumor types and its overexpression is known to correlate with increased metastatic capacity. To combine extravasation- and ligand-dependent targeting to NCAM overexpressing-cells in the tumor microenvironment, we developed a PEGylated NCAM-targeted dendritic polyglycerol (PG) conjugate. Here, we describe the synthesis, physico-chemical characterization and biological evaluation of a PG conjugate bearing the mitotic inhibitor paclitaxel (PTX) and an NCAM-targeting peptide (NTP). PG-NTP-PTX-PEG was evaluated for its ability to inhibit neuroblastoma progression in vitro and in vivo as compared to non-targeted derivatives and free drug. NCAM-targeted conjugate inhibited the migration of proliferating endothelial cells, suggesting it would be able to inhibit tumor angiogenesis. The targeting conjugate provided an improved binding and uptake on IMR-32 cells compared to non-targeted control. However, these results did not translate to our in vivo model on orthotopic neuroblastoma bearing mice.

Protein Corona Formation on Colloidal Polymeric Nanoparticles and Polymeric Nanogels: Impact on Cellular Uptake, Toxicity, Immunogenicity, and Drug Release Properties.

The adsorption of biomolecules to the surface of nanoparticles (NPs) following administration into biological environments is widely recognized. In particular, the "protein corona" is well understood in terms of formation kinetics and impact upon the biological interactions of NPs. Its presence is an essential consideration in the design of therapeutic NPs. In the present study, the protein coronas of six polymeric nanoparticles of prospective therapeutic use were investigated. These included three colloidal NPs-soft core-multishell (CMS) NPs, plus solid cationic Eudragit RS (EGRS), and anionic ethyl cellulose (EC) nanoparticles-and three nanogels (NGs)-thermoresponsive dendritic-polyglycerol (dPG) nanogels (NGs) and two amino-functionalized dPG-NGs. Following incubation with human plasma, protein coronas were characterized and their biological interactions compared with pristine NPs. All NPs demonstrated protein adsorption and increased hydrodynamic diameters, although the solid EGRS and EC NPs bound notably more protein than the other tested particles. Shifts toward moderately negative surface charges were also observed for all corona bearing NPs, despite varied zeta potentials in their pristine states. While the uptake and cellular adhesion of the colloidal NPs in primary human keratinocytes and human umbilical vein endothelial cells were significantly decreased when bearing the protein corona, no obvious impact was seen in the NGs. By contrast, corona bearing NGs induced marked increases in cytokine release from primary human macrophages not seen with corona bearing colloidal NPs. Despite this, no apparent enhancement to in vitro toxicity was noted. Finally, drug release from EGRS and EC NPs was assessed, where a decrease was seen in the EGRS NPs alone. Together these results provide a direct comparison of the physical and biological impact the protein corona has on NPs of widely varied character and in particular highlights a distinction between the corona's effects on NGs and colloidal NPs.

Metallo-Polymer Chain Extension Controls the Morphology and Release Kinetics of Microparticles Composed of Terpyridine-Capped Polylactides and their Stereocomplexes.

Control over morphology and porosity of supramolecular complexed polylactide (PLA) microparticles can be achieved by manipulation of the supramolecular interactions between their constituent polymeric building blocks. It is expected that such modular systems are ideal candidates to serve as degradable delivery carriers. In view of this goal, this study reports about a modular fabrication of biodegradable microparticles from terpyridine (TPy) and bisterpyridine (bisTPy) end-functionalized PLAs that can be transiently extended by chain association through differently strong complexation to three metal cations: Ni2+ , Co2+ , or Fe2+ . Further influence on the morphology of the particles can be exerted by hydrogen-bonding association of enantiomeric l- and d-PLA chains in the form of stereocomplexes. Both effects cause different stabilization of phase-separating TPy and bisTPy PLA micrograins in a process of droplet-based microfluidic particle templating, resulting in different forms of microparticle porosity. If the resulting particles are tailored such to be highly porous, they exhibit a faster release of a model drug, (S)-(+)-4-(3-amino-pyrrolidino)-7-nitrobenzo-furazan, than if they have smooth surfaces. As a result, control over the synthetic parameters, and hence, the particle porosity, can be used to tune the release profiles of drugs from the PLA microspheres.

New approaches from nanomedicine for treating leishmaniasis.

Leishmaniasis, a vector-borne disease caused by obligate intramacrophage protozoa, threatens 350 million people in 98 countries around the world. There are already 12 million infected people worldwide and two million new cases occur annually. Leishmaniasis has three main clinical presentations: cutaneous (CL), mucosal (ML), and visceral (VL). It is considered an opportunistic, infectious disease and the HIV-leishmaniasis correlation is well known. Antimonial compounds are used as first-line treatment drugs, but their toxicity, which can be extremely high, leads to a number of undesirable side effects and resultant failure of the patients to adhere to treatment. There is also a reported increase in Leishmania sp. resistance to these drugs. Nanotechnology has emerged as an attractive alternative because of its improved bioavailability and lower toxicity, and other characteristics that help to relieve the burden of this disease. In this review we will present some of the recent advances in the nanotechnological research regarding the treatment of leishmaniasis. The preclinical results regarding the approaches for a biomedical treatment of the disease have been encouraging, but further efforts will still be necessary for this therapy to have greater clinical applicability in humans.

Unexpected Chiro-Thermoresponsive Behavior of Helical Poly(phenylacetylene)s Bearing Elastin-Based Side Chains.

The thermoresponsive behavior of an elastin-based polymer can be altered by the polymeric macromolecular conformation. Thus, when the elastin basic amino acid sequence VPGVG is used as a pendant group of a poly(phenylacetylene) (PPA) its thermoresponsive behavior in water can be remotely detected through conformational changes on the formed helix. Circular dichroism at different temperatures shows an inversion of the first Cotton effect (450 nm) at 25.8 °C that matches with the cloud point temperature. The elastin-based side-chain poly(phenylacetylene) shows an upper critical solution temperature with low pH and concentration dependency, not expected in elastin-based polymers. It was found that the polymer self-assembles in water into spherical nanoparticles with hydrodynamic diameters of 140 nm at the hydrophobic state.

Transferrin Decorated Thermoresponsive Nanogels as Magnetic Trap Devices for Circulating Tumor Cells.

A rational design of magnetic capturing nanodevices, based on a specific interaction with circulating tumor cells (CTCs), can advance the capturing efficiency and initiate the development of modern smart nanoformulations for rapid isolation and detection of these CTCs from the bloodstream. Therefore, the development and evaluation of magnetic nanogels (MNGs) based on magnetic nanoparticles and linear thermoresponsive polyglycerol for the capturing of CTCs with overexpressed transferrin (Tf(+) ) receptors has been presented in this study. The MNGs are synthesized using a strain-promoted "click" approach which has allowed the in situ surface decoration with Tf-polyethylene glycol (PEG) ligands of three different PEG chain lengths as targeting ligands. An optimal value of around 30% of cells captures is achieved with a linker of eight ethylene glycol units. This study shows the potential of MNGs for the capture of CTCs and the necessity of precise control over the linkage of the targeting moiety to the capturing device.

Restoring the oncosuppressor activity of microRNA-34a in glioblastoma using a polyglycerol-based polyplex.

Glioblastoma multiforme (GBM) is the most common and aggressive primary neoplasm of the brain. Poor prognosis is mainly attributed to tumor heterogeneity, invasiveness, and drug resistance. microRNA-based therapeutics represent a promising approach due to their ability to inhibit multiple targets. In this work, we aim to restore the oncosuppressor activity of microRNA-34a (miR-34a) in GBM. We developed a cationic carrier system, dendritic polyglycerolamine (dPG-NH2), which remarkably improves miRNA stability, intracellular trafficking, and activity. dPG-NH2 carrying mature miR-34a targets C-MET, CDK6, Notch1 and BCL-2, consequently inhibiting cell cycle progression, proliferation and migration of GBM cells. Following complexation with dPG-NH2, miRNA is stable in plasma and able to cross the blood-brain barrier. We further show inhibition of tumor growth following treatment with dPG-NH2-miR-34a in a human glioblastoma mouse model. We hereby present a promising technology using dPG-NH2-miR-34a polyplex for brain-tumor treatment, with enhanced efficacy and no apparent signs of toxicity.

Stimuli-responsive nanogel composites and their application in nanomedicine.

Nanogels are nanosized crosslinked polymer networks capable of absorbing large quantities of water. Specifically, smart nanogels are interesting because of their ability to respond to biomedically relevant changes like pH, temperature, etc. In the last few decades, hybrid nanogels or composites have been developed to overcome the ever increasing demand for new materials in this field. In this context, a hybrid refers to nanogels combined with different polymers and/or with nanoparticles such as plasmonic, magnetic, and carbonaceous nanoparticles, among others. Research activities are focused nowadays on using multifunctional hybrid nanogels in nanomedicine, not only as drug carriers but also as imaging and theranostic agents. In this review, we will describe nanogels, particularly in the form of composites or hybrids applied in nanomedicine.

Thermosensitive dendritic polyglycerol-based nanogels for cutaneous delivery of biomacromolecules.

Genetic skin diseases caused by mutations resulting in diminished protein synthesis could benefit from local substitution of the missing protein. Proteins, however, are excluded from topical applications due to their physicochemical properties. We prepared protein-loaded thermoresponsive poly(N-isopropylacrylamide)-polyglycerol-based nanogels exhibiting a thermal trigger point at 35°C, which is favorable for cutaneous applications due to the native thermal gradient of human skin. At≥35°C, the particle size (~200nm) was instantly reduced by 20% and 93% of the protein was released; no alterations of protein structure or activity were detected. Skin penetration experiments demonstrated efficient intraepidermal protein delivery particularly in barrier deficient skin, penetration of the nanogels themselves was not detected. The proof of concept was provided by transglutaminase 1-loaded nanogels which efficiently delivered the protein into transglutaminase 1-deficient skin models resulting in a restoration of skin barrier function. In conclusion, thermoresponsive nanogels are promising topical delivery systems for biomacromolecules. FROM THE CLINICAL EDITOR: Many skin disorders are characterized by an absence of a specific protein due to underlying gene mutation. In this article, the authors described the use of a thermoresponsive PNIPAM-dPG nanogel for cutaneous protein delivery in a gene knock-down model of human skin. The results may have implication for nano-based local delivery of therapeutic agents in skin.

Double-degradable responsive self-assembled multivalent arrays--temporary nanoscale recognition between dendrons and DNA.

This article reports self-assembling dendrons which bind DNA in a multivalent manner. The molecular design directly impacts on self-assembly which subsequently controls the way these multivalent nanostructures bind DNA--this can be simulated by multiscale modelling. Incorporation of an S-S linkage between the multivalent hydrophilic dendron and the hydrophobic units responsible for self-assembly allows these structures to undergo triggered reductive cleavage, with dithiothreitol (DTT) inducing controlled breakdown, enabling the release of bound DNA. As such, the high-affinity self-assembled multivalent binding is temporary. Furthermore, because the multivalent dendrons are constructed from esters, a second slow degradation step causes further breakdown of these structures. This two-step double-degradation mechanism converts a large self-assembling unit with high affinity for DNA into small units with no measurable binding affinity--demonstrating the advantage of self-assembled multivalency (SAMul) in achieving highly responsive nanoscale binding of biological targets.

Nanogels: Smart tools to enlarge the therapeutic window of gene therapy.

Gene therapy can potentially treat a great number of diseases, from cancer to rare genetic disorders. Very recently, the development and emergency approval of nucleic acid-based COVID-19 vaccines confirmed its strength and versatility. However, gene therapy encounters limitations due to the lack of suitable carriers to vectorize therapeutic genetic material inside target cells. Nanogels are highly hydrated nano-size crosslinked polymeric networks that have been used in many biomedical applications, from drug delivery to tissue engineering and diagnostics. Due to their easy production, tunability, and swelling properties they have called the attention as promising vectors for gene delivery. In this review, nanogels are discussed as vectors for nucleic acid delivery aiming to enlarge gene therapy's therapeutic window. Recent works highlighting the optimization of inherent transfection efficiency and biocompatibility are reviewed here. The importance of the monomer choice, along with the internal structure, surface decoration, and responsive features are outlined for the different transfection modalities. The possible sources of toxicological endpoints in nanogels are analyzed, and the strategies to limit them are compared. Finally, perspectives are discussed to identify the remining challenges for the nanogels before their translation to the market as transfection agents.

Nano-in-nano enteric protein delivery system: coaxial Eudragit® L100-55 fibers containing poly(N-vinylcaprolactam) nanogels.

Oral protein delivery holds significant promise as an effective therapeutic strategy for treating a wide range of diseases. However, effective absorption of proteins faces challenges due to biological barriers such as harsh conditions of the stomach and the low permeability of mucous membranes. To address these challenges, this article presents a novel nano-in-nano platform designed for enteric protein delivery. This platform, obtained by electrospinning, involves a coaxial arrangement comprising poly(N-vinylcaprolactam) nanogels (NGs) enclosed within nanofibers of Eudragit® L100-55 (EU), a pH-responsive polymer. The pH-selective solubility of EU ensures the protection of NGs during their passage through the stomach, where the fibers remain intact at low pH, and releases them in the intestine where EU dissolves. The switchable characteristic of this nano-in-nano platform is confirmed by using NGs loaded with a model protein (ovalbumin), which is selectively released when the intestinal pH is achieved. The versatility of this nano-in-nano delivery platform is demonstrated by the ability to modify the fibers dissolution profile simply by adjusting the concentration of EU used in the electrospinning process. Furthermore, by tuning the properties of NGs, the potential applications of this platform can be further extended, paving the way for diverse therapeutic possibilities.