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The spatiotemporal pH-triggered controlled release of a hydrophilic probe in a pH-responsive PGUV system demonstrates its potential as a biomimetic system for drug delivery, microreactors and artificial cell mimics.

The delivery of therapeutics into sites of action by using cargo-delivery platforms potentially minimizes their premature degradation and fast clearance from the bloodstream. Additionally, drug-loaded stimuli-responsive supramolecular assemblies can be produced to respond to the inherent features of tumor microenvironments, such as extracellular acidosis. We report in this framework the use of pH-responsive polymersomes (PSs) manufactured using poly([N-(2-hydroxypropyl)] methacrylamide)35-b-poly[2-(diisopropylamino)ethyl methacrylate]75 as the building unit (PHPMA35-b-PDPA75). The self-assemblies were produced with desired size towards long circulation time and tumor accumulation (hydrodynamic diameter - DH ~ 100 nm), and they could be successfully loaded with 10% w/w DOX (doxorubicin), while maintaining colloidal stability. The DOX loaded amount is presumably mainly burst-released at the acidic microenvironment of tumors thanks to the pH-switchable property of PDPA (pKa ~ 6.8), while reduced drug leakage has been monitored in pH 7.4. Compared to the administration of free DOX, the drug-loaded supramolecular structures greatly enhanced the therapeutic efficacy with effective growth inhibition of EL4 lymphoma tumor model and 100% survival rate in female C57BL/6 black mice over 40 days. The approach also led to reduced cardiotoxic effect. These features highlight the potential application of such nanotechnology-based treatment in a variety of cancer therapies where low local pH is commonly found, and emphasize PHPMA-based nanomedicines as an alternative to PEGylated formulations.

A two-step synthetic approach via the combination of living cationic ring-opening (CROP) and reversible addition–fragmentation chain transfer (RAFT) polymerization techniques was used to produce novel amphiphilic block copolymers based on the water-soluble poly(2-methyl-2-oxazoline) (PMeOx), which holds protein repelling properties, linked to the hydrophilic–hydrophobic pH-responsive block poly[2-(diisopropylamino)ethyl methacrylate] (PDPA). Hydrodynamic flow focusing nanoprecipitation microfluidics (MF) was further employed to manufacture block copolymer self-assemblies. Interestingly, although all the synthesized macromolecules contained higher amounts of the pH-responsive segment, the microfluidic approach allowed the manufacturing of core–shell micelles and polymersomes. The morphology seems to be driven by the overall molecular weight of the block copolymers rather than by the hydrophilic-to-hydrophobic weight ratio. Longer and shorter amphiphilic chains enabled the manufacturing of core–shell assemblies and polymeric vesicles, respectively. The use of PMeOx and PDPA blocks confers serum stability and pH-responsive behavior to the nanoparticles in a pH window which is particularly useful for tumour detection and therapy. The self-assembled nanostructures are non-toxic even at fairly high polymer concentrations. All these features therefore can be useful in the design of pH-triggered nanoplatforms of distinct morphologies towards a variety of biomedical applications, for instance, the loading and delivery of hydrophobic and hydrophilic therapeutics.

The advances in polymer chemistry have allowed the preparation of biomedical polymers using human metabolites as monomers that can hold unique properties beyond the required biodegradability and biocompatibility. Herein, we demonstrate the use of endogenous human metabolites (succinic and dilinoleic acids) as monomeric building blocks to develop a new series of renewable resource-based biodegradable and biocompatible copolyesters. The novel copolyesters were characterized in detail employing several standard techniques, namely 1H NMR, 13C NMR, and FTIR spectroscopy and SEC, followed by an in-depth thermomechanical and surface characterization of their resulting thin films (DSC, TGA, DMTA, tensile tests, AFM, and contact angle measurements). Also, their anti-fungal biofilm properties were assessed via an anti-fungal biofilm assay and the biological properties were evaluated in vitro using relevant human-derived cells (human mesenchymal stem cells and normal human dermal fibroblasts). These novel highly biocompatible polymers are simple and cheap to prepare, and their synthesis can be easily scaled-up. They presented good mechanical, thermal and anti-fungal biofilm properties while also promoting cell attachment and proliferation, outperforming well-known polymers used for biomedical applications (e.g. PVC, PLGA, and PCL). Moreover, they induced morphological changes in the cells, which were dependent on the structural characteristics of the polymers. In addition, the obtained physicochemical and biological properties can be design-tuned by the synthesis of homo- and -copolymers through the selection of the diol moiety (ES, PS, or BS) and by the addition of a co-monomer, DLA. Consequently, the copolyesters presented herein have high application potential as renewable and cost-effective biopolymers for various biomedical applications.

Background Reactive oxygen species (ROS), such as hydrogen peroxide and superoxide, trigger biodegradation of polymer-based nanoparticles (NPs) bearing pinacol-type boronic ester groups. These NPs may selectively release their cargo, in this case paclitaxel (PTX), at the high levels of ROS present in the intracellular environment of inflamed tissues and most tumors. Purpose The main objective was to determine anti-tumor efficacy of PTX-loaded ROS-sensitive NPs and to examine whether macrophage infiltration had any impact on treatment efficacy. Methods NPs were synthesized and their characteristics in the presence of H2O2 were demonstrated. Both confocal microscopy as well as flow cytometry approaches were used to determine degradation of ROS-sensitive NPs. HeLa cells were cultured in vitro and used to establish tumor xenografts in nude mice. In vivo experiments were performed to understand toxicity, biodistribution and anti-tumor efficacy of the NPs. Moreover, we performed immunohistochemistry on tumor sections to study infiltration of M1 and M2 subsets of macrophages. Results We demonstrated that PTX delivered in NPs containing a ROS-sensitive polymer exhibits a better anti-tumor efficacy than PTX in NPs containing ROS-non-sensitive polymer, free PTX or Abraxane® (nab-PTX). The biodistribution revealed that ROS-sensitive NPs exhibit retention in liver, spleen and lungs, suggesting a potential to target cancer metastasizing to these organs. Finally, we demonstrated a correlation between infiltrated macrophage subsets and treatment efficacy, possibly contributing to the efficient anti-tumor effects. Conclusion Treatment with ROS-sensitive NPs containing PTX gave an improved therapeutic effect in HeLa xenografts than their counterpart, free PTX or nab-PTX. Our data revealed a correlation between macrophage infiltration and efficiency of the different antitumor treatments, as the most effective NPs resulted in the highest infiltration of the anti-tumorigenic M1 macrophages.

Contains fulltext : 244600.pdf (Publisher’s version ) (Open Access) Anticancer drug delivery strategies are designed to take advantage of the differential chemical environment in solid tumors independently, or to high levels of reactive oxygen species (ROS) or to low pH, compared to healthy tissue. Here, the design and thorough characterization of two functionalizable "AND gate" multiresponsive (MR) block amphiphilic copolymers are reported, aimed to take full advantage of the coexistence of two chemical cues-ROS and low pH-present in the tumor microenvironment. The hydrophobic blocks contain masked pH-responsive side chains, which are exposed exclusively in response to ROS. Hence, the hydrophobic polymer side chains will undergo a charge shift in a very relevant pH window present in the extracellular milieu in most solid tumors (pH 5.6-7.2) after demasking by ROS. Doxorubicin (DOX)-loaded nanosized "AND gate" MR polymersomes (MRPs) are fabricated via microfluidic self-assembly. Chemical characterization reveals ROS-dependent pH sensitivity and accelerated DOX release under influence of both ROS and low pH. Treatment of tumor-bearing mice with DOX-loaded nonresponsive and "AND gate" MRPs dramatically decreases cardiac toxicity. The most optimal "AND gate" MRPs outperform free DOX in terms of tumor growth inhibition and survival, shedding light on chemical requirements for successful cancer nanomedicine.

We report the controlled synthesis of polymer-stabilized silver nanoparticles (AgNPs) by using microfluidic devices. The microfluidic-based method enabled the preparation of sub-50 nm AgNPs which are much more homogenous compared to those produced in batch reactors where the control over flow and mixing conditions was not performed. The concentration of the silver precursor (silver nitrate - AgNO₃) can be tuned to reach smaller or larger nanoparticles, although within a fairly narrow range. Regardless of the polymeric shell, the reducing agent concentration influences the size and polydispersity of the manufactured silver colloids, and relatively lower amounts allow for the manufacturing of more homogeneous nanoparticles. Notably, the use of the block copolymer PEO-b-P2VP as stabilizing agent leads to larger nanoparticles (23–51 nm) compared to those stabilized by PVP (7–14 nm) as possibly linked to different arrangements of the polymer chains at the interface between the precursor solutions. The produced AgNPs are highly uniform, with size distribution width influenced by the polymer concentration (FWHM < 100 nm were determined at higher concentrations), although this variable does not have a distinguished effect on the final size of the manufactured colloids. Overall, we provide relevant new knowledge within the framework of polymer-stabilized AgNPs since a variety of other polymer chains can be probed, possibly with different outcomes regarding the final particle size. The reported findings can thus guide to significant advances towards the manufacturing of highly homogeneous polymer-coated metallic colloids, particularly when a target size is required.

The lack of cellular and tissue specificities in conventional chemotherapies along with the generation of a complex tumor microenvironment (TME) limits the dosage of active agents that reaches tumor sites, thereby resulting in ineffective responses and side effects. Therefore, the development of selective TME-responsive nanomedicines is of due relevance toward successful chemotherapies, albeit challenging. In this framework, we have synthesized novel, ready-to-use ROS-responsive amphiphilic block copolymers (BCs) with two different spacer chemistry designs to connect a hydrophobic boronic ester-based ROS sensor to the polymer backbone. Hydrodynamic flow focusing nanoprecipitation microfluidics (MF) was used in the preparation of well-defined ROS-responsive PSs; these were further characterized by a combination of techniques [

In the last half-century, the development of biodegradable polyesters for biomedical applications has advanced significantly. Biodegradable polyester materials containing external stimuli-sensitive linkages are favored in the development of therapeutic devices for pharmacological applications such as delivery vehicles for controlled/sustained drug release. These selectively biodegradable polyesters degrade after particular external stimulus (e.g., pH or redox potential change or the presence of certain enzymes). This review outlines the current development of biodegradable synthetic polyesters materials able to undergo hydrolytic or enzymatic degradation for various biomedical applications, including tissue engineering, temporary implants, wound healing and drug delivery.

Polymers 13(9), 1465 (1-14) (2021). doi:10.3390/polym13091465, Here, we report on the construction of biodegradable poly(ethylene oxide monomethyl ether) (MPEO)-b-poly(��-caprolactone) (PCL) nanoparticles (NPs) having acid-labile (acyclic ketal group) linkage at the block junction. In the presence of acidic pH, the nanoassemblies were destabilized as a consequence of cleaving this linkage. The amphiphilic MPEO-b-PCL diblock copolymer self-assembled in PBS solution into regular spherical NPs. The structure of self-assemble and disassemble NPs were characterized in detail by dynamic (DLS), static (SLS) light scattering, small-angle X-ray scattering (SAXS), and transmission electron microscopy (TEM). The key of the obtained NPs is using them in a paclitaxel (PTX) delivery system and study their in vitro cytostatic activity in a cancer cell model. The acid-labile ketal linker enabled the disassembly of the NPs in a buffer simulating an acidic environment in endosomal (pH ~5.0 to ~6.0) and lysosomal (pH ~4.0 to ~5.0) cell compartments resulting in the release of paclitaxel (PTX) and formation of neutral degradation products. The in vitro cytotoxicity studies showed that the activity of the drug-loaded NPs was increased compared to the free PTX. The ability of the NPs to release the drug at the endosomal pH with concomitant high cytotoxicity makes them suitable candidates as a drug delivery system for cancer therapy., Published by MDPI, Basel

A new reactive oxygen species (ROS)-sensitive, self-immolative biodegradable polyoxalate prodrug based on the anticancer chemotherapeutic hormone analog diethylstilbestrol was synthesized via one-pot step-growth polymerization. The nanoparticles prepared from this prodrug undergo self-immolative degradation releasing the chemotherapeutic drug in ROS-rich environments, e.g., in cancer cells. This new ROS self-immolative polyprodrug backbone eliminates the need for a linker between polymer chain and drug, resulting in a more specific drug release and minimized toxic side effects to non-ROS-producing cells as proven by in vitro experiments. The strategy enables re-utilization of a successful chemotherapeutic agent that has been clinically under-utilized due to dose-related side effects.

A new drug-delivery system of polymer nanoparticles (NPs) bearing pinacol-type boronic ester and alkyne moieties displaying triggered self-immolative polymer degradation in the presence of reactive oxygen species (ROS) with the capability of cellular imaging is presented. The NPs specifically release their drug cargo under concentrations of ROS that are commonly found in the intracellular environment of certain tumors and of inflamed tissues and exhibit significant cytotoxicity to cancer cells compared to their non-ROS-responsive counterparts.

The aggregation kinetics of negatively charged borate-stabilized silver nanoparticles (NPs) induced by the cationic regioregular polythiophene polyelectrolyte poly{3-[6-(1-methylimidazolium-3-yl)hexyl]thiophene-2,5-diyl bromide} (PMHT-Br) and the morphology of formed aggregates have been investigated via ultraviolet-visible light (UV-vis) spectroscopy, transmission electron microscopy (TEM), zeta (ζ) potential measurements, dynamic light scattering (DLS), and time-resolved small-angle X-ray scattering (SAXS). Two or three populations of NPs are formed within milliseconds upon mixing the components, which differ in the mean size, extent of polymer coating, and time stability. These characteristics are primarily controlled by the PMHT-Br to Ag-NPs ratio. Population of single NPs of a mean size of ∼5 nm is present in every system and is mostly stable for a long time. At low ratios, the single NPs are most probably almost free of polymer chains and the second population includes slow, but in a limited extent, growing NPs in which single NPs might be interconnected by polymer chains. At the ratios corresponding to the charge balance in the system (ca. zero ζ-potential of NPs), the NPs aggregate, forming a second population that continuously grows in size, and finally undergo sedimentation. At the high ratios, three long-time stable populations of NPs are observed, having mean sizes of ca. 5, 13, and 35 nm; all NPs should be fully coated with PMHT-Br, giving them a positively charged stabilizing shell.

The potential use of polyester polymeric nanoparticles (NPs) as drug nanocarriers is well-documented. Nevertheless, structural changes due to hydrophobic drug loading and release have been rarely explored. Herein, we have used static and dynamic light scattering (SDLS), small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and cryo-TEM to probe how the entrapment of a hydrophobic drug molecule changes the nanoparticles feature. The presence of the hydrophobic drug molecule modifies the inner structure of the NPs. The polymeric assemblies are characterized by differences in their densities (∼ 0.06 g cm-3 for poly(D,L-lactide) – PLA or poly(D,L-lactide-co-glycolide – PLGA) and 0.46 g cm-3 for poly[(butylene succinate)-co-(butylene dilinoleate)] − PBSBDL). They are thus water swollen in the drug-free condition. The NPs were further prepared by using the same polyesters and given amounts of the poorly water-soluble drug paclitaxel (PTX). The density (dNP), RG (radius of gyration), RH (hydrodynamic radius), RG/RH and R (contrast radius) have been monitored as a function of the amount of drug loaded. The drug entrapment increased the size of PLA and PLGA NPs. On the other hand, it also promoted the shrinkage of PBSBDL NPs. These observations revealed that changes in the inner structure of soft nanoparticles caused by drug loading is not straightforward and it mainly depends on the strength of van der Waals interactions between the polyester core and the probe which is connected to their chemical composition and hydrophobicity. These findings are crucial to understand the key physicochemical parameters involved in the interactions between drug and polymer that affects the final particle structure and influence its loading, release and degradation.

A series of new double-hydrophilic and hydrophobic biocompatible ABC triblock terpolymers with different molecular weights of the PCL block (herein referred to as MPEO44-b-PEtOx263-b-PCL87, MPEO44-b-PEtOx263-b-PCL175, MPEO44-b-PEtOx263-b-PCL262) were successfully synthesized by a three-step pathway using a combination of living cationic and anionic ring-opening polymerization (ROP). First, α-methoxy-ω-hydroxy-poly(ethylene oxide) (MPEO) was end-capped with p-toluenesulfonyl chloride. ω-Tosyl-MPEO was used in the second step as a macroinitiator for the ROP of 2-ethyl-2-oxazoline (EtOx) to form the diblock copolymer, MPEO-b-PEtOx. Finally, the prepared diblock copolymer was used as a macroinitiator for the design of the PCL block by ROP of e-caprolactone (e-CL). Properties of the newly obtained compounds (macroinitiator, AB diblock and ABC triblock terpolymers) were assessed by 1H NMR and FT-IR spectroscopy and SEC analysis. The selected MPEO44-b-PEtOx263-b-PCL87 triblock terpolymers self-assembled under buffer-simulated physiological conditions into nanoparticles, which were fully characterized by static and dynamic light scattering, nanoparticle tracking analysis and cryo-transmission electron microscopy (cryo-TEM). The combination of the scattering methods revealed a temperature-induced aggregation driven by hydrogen bonding with the LCST approximately between 56 and 60 °C.

Nonlinear amphiphilic block copolymer architectures with precisely controlled structures bring new challenges to biomedical materials research. The paper describes the straightforward synthesis of new “snake tongue“ Y-shaped terpolymers containing poly(ethylene oxide) (PEO), poly(2-ethyl-2-oxazoline) (PEtOx) and poly(e-caprolactone) (PCL) blocks into structure [AB(C)2] (herein referred to as [MPEO44-b-PEtOx252-b-(PCL)2×44], [MPEO44-b-PEtOx252-b-(PCL)2×87], [MPEO44-b-PEtOx252-b-(PCL)2×131]). A series of well-defined Y-shaped terpolymers were successfully synthesised by a combination of living cationic and anionic ring-opening polymerization (ROP). The selected Y-shaped [MPEO44-b-PEtOx252-b-(PCL)2×44] terpolymer self-assembly was characterised in detail by static and dynamic light scattering, nanoparticle tracking analysis and cryo-transmission electron microscopy. The physico-chemical properties as well as the molecular architecture effect on the self-assembled structures and on the LCST were compared with the Y-shaped [MPEO44-b-PEtOx252-b-(PCL)2×87] and the [MPEO44-b-PEtOx252-b-(PCL)2×131] terpolymers. The results indicated a temperature-induced aggregation with an LCST between 60–63 °C for the [MPEO44-b-PEtOx252-b-(PCL)2×44], at 60 °C for the [MPEO44-b-PEtOx252-b-(PCL)2×87] and between 45–50 °C for the [MPEO44-b-PEtOx252-b-(PCL)2×131] with significant differences in the supramolecular self-assembly behaviour compared with the analogous linear structure, clearly indicating the crucial effect of the molecular architecture. Furthermore, the increase of the molecular weight fraction of the hydrophobic block on the Y-shaped triblock terpolymers likely induced a decrease of the LCST.

The development of nanocarriers for biomedical applications requires that these nanocarriers have special properties, including resistance to nonspecific protein adsorption. In this study, the fouling properties of PLA- and PCL-based block copolymer nanoparticles (NPs) have been evaluated by placing them in contact with model proteins. Block copolymer NPs were produced through the self-assembly of PEOm-b-PLAn and PEOm-b-PCLn. This procedure yielded nanosized objects with distinct structural features dependent on the length of the hydrophobic and hydrophilic blocks and the volume ratio. The protein adsorption events were examined in relation to size, chain length, surface curvature, and hydrophilic chain density. Fouling by BSA and lysozyme was considerably reduced as the length of the hydrophilic PEO-stabilizing shell increases. In contrast to the case of hydrophilic polymer-grafted planar surfaces, the current investigations suggest that the hydrophilic chain density did not markedly influence protein fouling. The protein adsorption took place at the outer surface of the NPs since neither BSA nor lysozyme was able to diffuse within the hydrophilic layer due to geometric restrictions. Protein binding is an exothermic process, and it is modulated mainly by polymer features. The secondary structures of BSA and lysozyme were not affected by the adhesion phenomena.

Insulin was used as model protein to developed innovative Solid Lipid Nanoparticles (SLNs) for the delivery of hydrophilic biotech drugs, with potential use in medicinal chemistry. SLNs were prepared by double emulsion with the purpose of promoting stability and enhancing the protein bioavailability. Softisan®100 was selected as solid lipid matrix. The surfactants (Tween®80, Span®80 and Lipoid®S75) and insulin were chosen applying a 22 factorial design with triplicate of central point, evaluating the influence of dependents variables as polydispersity index (PI), mean particle size (z-AVE), zeta potential (ZP) and encapsulation efficiency (EE) by factorial design using the ANOVA test. Therefore, thermodynamic stability, polymorphism and matrix crystallinity were checked by Differential Scanning Calorimetry (DSC) and Wide Angle X-ray Diffraction (WAXD), whereas the effect of toxicity of SLNs was check in HepG2 and Caco-2 cells. Results showed a mean particle size (z-AVE) width between 294.6 nm and 627.0 nm, a PI in the range of 0.425–0.750, ZP about −3 mV, and the EE between 38.39% and 81.20%. After tempering the bulk lipid (mimicking the end process of production), the lipid showed amorphous characteristics, with a melting point of ca. 30 °C. The toxicity of SLNs was evaluated in two distinct cell lines (HEPG-2 and Caco-2), showing to be dependent on the concentration of particles in HEPG-2 cells, while no toxicity in was reported in Caco-2 cells. SLNs were stable for 24 h in in vitro human serum albumin (HSA) solution. The resulting SLNs fabricated by double emulsion may provide a promising approach for administration of protein therapeutics and antigens.

A new biocompatible and biodegradable diblock copolymer that contains a specific acid-labile degradable linkage (acyclic ketal group) between the hydrophobic poly(e-caprolactone) (PCL) and the hydrophilic poly(ethylene oxide monomethyl ether) (MPEO) blocks is described herein. A multi-step synthetic method that combines carbodiimide chemistry, a “click” reaction and ring-opening polymerization (ROP) was employed to successfully produce a series of MPEO-b-PCL diblock copolymers (herein referred to as MPEO44-b-PCL17 and MPEO44-b-PCL44). 2-{[2-(2-Azidoethoxy)propan-2-yl]}ethan-1-ol was obtained as a linker between the two blocks through a three-step synthetic approach. Furthermore, a newly developed α-methoxy-ω-hydroxy-poly(ethylene oxide) that contains an acid-labile ketal linkage was designed as a macroinitiator via a “click” reaction for the sequential controlled ring-opening polymerization of e-CL. The newly obtained compounds (precursors, macromer, macroinitiator and final diblock copolymers) were assessed by 1H NMR, 13C NMR and FT-IR spectroscopy and SEC analysis, which are described in this manuscript. Upon dissolution in a mild organic solvent, the MPEO44-b-PCL17 block copolymer self-assembled in water–PBS into regular, spherical, stable nanoparticles (NPs). Furthermore, the presence of the acid-labile ketal linker enabled the disassembly of these nanoparticles in a buffer that simulated acidic cytosolic or endosomal conditions in tumour cells as evaluated by dynamic light scattering (DLS), nanoparticle tracking analysis (NTA) and transmission electron microscopy (TEM) images. This disassembly led to hydrolysis profiles that resulted in neutral degradation products.

Surfactant-free PLGA polymeric nanoparticles (PNPs) with hydrodynamic radius (RH) ranging from 25.8 nm to 128.5 nm were successfully obtained through nanoprecipitation by controlling a variety of physicochemical parameters. The size of the generated PLGA PNPs could be controlled by adjusting the polymer concentration, the choice of organic solvent, mixing different organic solvents or by changing temperature and ionic strength. By optimizing such parameters sub-100 nm uniform PNPs can be produced through this methodology including the advantage and ability to scale-up production. The PNPs have shown a size-dependent effect on the organic solvent and polymer concentration. On the other hand, the polymer–solvent interactions seem not to play a substantial role in the final dimension of the polymer colloids. It has been also evidenced that the size of PNPs can be precisely and linearly tuned by using solvent mixtures as organic phase.

Non-specific protein adsorption from complex biological media, especially from blood plasma, is an urgent challenge for the application of nanoparticles as delivery systems, diagnostics, and other biomedical application. Nanocapsules (NC) prepared from FDA-approved degradable poly(ɛ-caprolactone) shell and Mygliol 812 ® oil in the core were coated with mono-methoxy terminated oligo(ethylene glycol) methacrylate (poly(MeOEGMA)) polymer brush layers with a well-controlled thickness at the nanometer scale up to 350 nm using surface initiated atom transfer radical polymerization in water or phosphate buffered saline. Incubation of uncoated NC with human serum albumin solution, fetal bovine serum, or human blood plasma resulted in fast aggregation observed by dynamic light scattering as an increase in diameter of particles present in the solutions. Conversely, these biological fluids affected only marginally the size distribution of the NC coated with a 60 nm thick poly(MeOEGMA) layer. The high suspension stability of the coated NC in complex biological fluids was related to the suppressed deposition of proteins from these fluids observed by surface plasmon resonance (SPR) on analogous poly(MeOEGMA) layer prepared on flat surfaces of SPR chips.

The objective of this work was to verify if hydrophilic gels containing benzophenone-3 loaded nanocapsules (HG-NCBZ3) could improve the sunscreen in vitro effectiveness against UVA radiation and its photostability compared to a conventional hydrogel containing the free sunscreen (HG-BZ3). In parallel, the immune response of the nanostructured system was evaluated by mouse ear swelling test and the local lymph node assay. The nanocapsules were prepared by interfacial deposition of poly(epsilon-caprolactone) and characterized in terms of particle size, polydispersity index, zeta potential, drug content and encapsulation efficiency. HG-NCBZ3 UV scans showed higher absorption intensity values than HG-NCplacebo, prepared using unloaded nanocapsules. Films of the gels were irradiated with UVA light and the BZ3 recovery was evaluated by HPLC. BZ3 recovery decreased from 100% to 29% for HG-BZ3 and to 56% for HG-NCBZ3 after 13 h. After wavelength scans within 13 h, the relative areas under the curves (AUC) decreased from 1.00 to 0.62 for HG-BZ3 and remained constant for HG-NCBZ3. Sensitization assay showed that stimulation indexes lower than 3 for all the hydrogel samples. Formulations did not induce increases higher than 10% in ear swelling, indicating that the hydrogels did not cause cutaneous sensitization in mice. The nanoencapsulation improved both the photostability and the effectiveness of BZ3 compared to the non-encapsulated sunscreen and the topical application of free and nanoencapsulated BZ3 did not produce significant allergy response in mice.

The potential of self-assembled nanoparticles (NPs) containing the fine tunable pH-responsive properties of the hydrophobic poly[2-(diisopropylamino)ethyl methacrylate] (PDPA) core and the protein repellence of the hydrophilic poly[N-(2-hydroxypropyl)methacrylamide] (PHPMA) shell for in vitro cytostatic activity has been explored on cancer cells. The amphiphilic diblock copolymer poly[N-(2-hydroxypropyl)methacrylamide]-b-poly[2-(diisopropylamino)ethyl methacrylate] (PHPMA-b-PDPA) synthesized by a reversible addition–fragmentation chain transfer (RAFT) technique allows for excellent control of the polymer chain length for methacrylamides. The PHPMA-b-PDPA block copolymer dissolved in an organic solvent (ethanol/dimethylformamide) undergoes nanoprecipitation in phosphate buffer saline (PBS, pH [similar] 7.4) and self-assembles into regular spherical NPs after solvent elimination. The NPs’ structure was characterized in detail by dynamic (DLS), static (SLS) and electrophoretic (ELS) light scattering, small angle X-ray scattering (SAXS), and cryo-transmission electron microscopy (cryo-TEM). The PHPMA chains prevented the fouling of proteins resulting in a remarkable stability of the NPs in serum. On decreasing pH the hydrophobic PDPA block becomes protonated (hydrophilised) in a narrow range of pH (6.51 < pH < 6.85; ΔpH [similar] 0.34) resulting in the fast disassembly of the NPs and chemotherapeutic drug release in a simulated acidic environment in endosomal and lysosomal compartments. A minimal amount of drug was released above the threshold pH of 6.85. The in vitro cytotoxicity studies showed an important increase in the activity of the NPs loaded with drug compared to the free drug. The particle\'s size below the cut-off size of the leaky pathological vasculature (less than 100 nm), the excellent stability in serum and the ability to release a drug at the endosomal pH with concomitant high cytotoxicity make them suitable candidates for cancer therapy, namely for treatment of solid tumours exhibiting high tumor accumulation of NPs due to the Enhanced Permeability and Retention (EPR) effect.

Herein, we present the intrinsic property of well-known polyesters [poly(alkene succinates)], as Candida albicans and Candida tropicalis biofilm inhibitors with potential to substantially reduce the incidence of device-associated infections in, e.g., indwelling catheters and sutures. These new biopolymer applications, either for manufacturing or coating medical devices, present innovative features such as: simple and cheap preparation, easy scaling-up, good mechanical and thermal resistance properties, and antibiofilm ability without any specific surface functionalization or antimicrobial agent encapsulation. Furthermore, the polyesters are shown to be highly biocompatible, promote human mesenchymal stem cell (hMSC) attachment and proliferation, inducing morphological changes, which are dependent on the polymer structural characteristics, making them promising candidates for materials in specialized medical devices and in the tissue engineering field.

The ether-functionalized imidazolium ionic liquids (IL) applied in the silica sol-gel process demonstrated a defined coordination potential. These IL display the capacity to control the system organization from the reactions' first moments through a dynamic system-assembling ability, being the sum of ionic and physical interactions, i.e. Coulomb forces, H-bonding and London forces. The initial hydrolysis steps of tetraethyl orthosilicate (TEOS) in the presence of these IL were followed by Fourier transform infrared spectroscopy (FTIR) and dynamic light scattering (DLS), both in time-resolved experiments, in an attempt to correlate the structuring and the bonding dynamics of these systems.

The preparation of core-shell polymeric nanoparticles simultaneously loaded with docetaxel (DTXL) and doxorubicin (DOX) is reported herein. The self-assembly of the aliphatic biodegradable copolyester PBS/PBDL (poly(butylene succinate-co-butylene dilinoleate)) and HPMA-based copolymers (N-(2-hydroxypropyl)methacrylamide-based copolymers) hydrophobically modified by the incorporation of cholesterol led to the formation of narrow-size-distributed (PDI

Selective protein fouling on block copolymer micelles with well-known potential for tumour-targeting drug delivery was evidenced by using dynamic light scattering measurements. The stability and interaction of block copolymer micelles with model proteins (BSA, IgG, lysozyme and CytC) is reported for systems featuring a hydrophobic (poly[2-(diisopropylamino)-ethyl methacrylate]) (PDPA) core and hydrophilic coronas comprising poly(ethylene oxide)/poly(glycerol monomethacrylate) (PEO-b-PG2MA) or poly[2-(methacryloyloxy)ethyl phosphorylcholine] (PMPC). The results revealed that protein size and hydrophilic chain density play important roles in the observed interactions. The PEO(113)-b-PG2MA(30)-b-PDPA(50) nanoparticles are stable and protein adsorption is prevented at all investigated protein environments. The successful protein-repellent characteristic of these nanoparticles is attributed to a high hydrophilic surface chain density (0.1 chains per nm(2)) and to the length of the hydrophilic chains. On the other hand, although PMPC also has protein-repellent characteristics, the low surface chain density of the hydrophilic shell is supposed to enable interactions with small proteins. The PMPC(40)-b-PDPA(70) micelles are stable in BSA and IgG environments due to weak repulsion forces between PMPC and the proteins, to the hydration layer, and particularly to a size-effect where the large BSA (R(H) = 4.2 nm) and IgG (R(H) = 7.0 nm) do not easily diffuse within the PMPC shell. Conversely, a clear interaction was observed with the 2.1 nm radius lysozyme. The lysozyme protein can diffuse within the PMPC micellar shell towards the PDPA hydrophobic core in a process favored by its smaller size and the low hydrophilic PMPC surface chain density (∼0.049 chains per nm(2)) as compared to PEO-b-PG2MA (∼0.110 chains per nm(2)). The same behavior was not evidenced with the 2.3 nm radius positively charged CytC, probably due to its higher surface hydrophilicity and the consequent chemical incompatibility with PDPA.

New Melatonin-loaded vesicular nanocarriers were prepared by interfacial deposition using a blend of an amphiphilic diblock copolymer, poly(methyl methacrylate)-block-poly(2-(dimethylamino)ethyl methacrylate), PMMA-b-PDMAEMA, with poly(epsilon-caprolactone), PCL. Particle size and morphology of the nanocarriers was evaluated. Dynamic light scattering shows that the nanocarriers have hydrodynamic radii between 100 and 180 nm, with unimodal particle size distribution for each formulation. Shape and structure were visualized by transmission electron microscopy (TEM), cryogenic TEM and scanning electron microscopy. Standard TEM for nanocapsules showed an oily core surrounded by a thin layer composed by PCL/PMMA-b-PDMAEMA. Cryo-TEM also indicated the presence of spherical nano-objects with a diffuse polymer corona. Encapsulation efficiencies were determined assaying the nanoparticles by HPLC and higher values of ca. 25% are shown by the nanocapsules. We could successfully incorporate platinum nanoparticles into the nanocarrier as evidenced by TEM, which opens up the possibility for promising applications like monitoring the encapsulated drug in the body.

The objective of this work was to verify if hydrophilic gels containing benzophenone-3 loaded nanocapsules (HG-NCBZ3) could improve the sunscreen in vitro effectiveness against UVA radiation and its photostability compared to a conventional hydrogel containing the free sunscreen (HG-BZ3). In parallel, the immune response of the nanostructured system was evaluated by mouse ear swelling test and the local lymph node assay. The nanocapsules were prepared by interfacial deposition of poly(epsilon-caprolactone) and characterized in terms of particle size, polydispersity index, zeta potential, drug content and encapsulation efficiency. HG-NCBZ3 UV scans showed higher absorption intensity values than HG-NCplacebo, prepared using unloaded nanocapsules. Films of the gels were irradiated with UVA light and the BZ3 recovery was evaluated by HPLC. BZ3 recovery decreased from 100% to 29% for HG-BZ3 and to 56% for HG-NCBZ3 after 13 h. After wavelength scans within 13 h, the relative areas under the curves (AUC) decreased from 1.00 to 0.62 for HG-BZ3 and remained constant for HG-NCBZ3. Sensitization assay showed that stimulation indexes lower than 3 for all the hydrogel samples. Formulations did not induce increases higher than 10% in ear swelling, indicating that the hydrogels did not cause cutaneous sensitization in mice. The nanoencapsulation improved both the photostability and the effectiveness of BZ3 compared to the non-encapsulated sunscreen and the topical application of free and nanoencapsulated BZ3 did not produce significant allergy response in mice.

The aim of this work was to investigate if the indomethacin ethyl ester (IndOEt) released from lipid-core nanocapsules (NC) is converted into indomethacin (IndOH) in the intestine lumen, intestine wall or after the particles reach the blood stream. NC-IndOEt had monomodal size distribution (242 nm; PDI 0.2) and zeta potential of -11 mV. The everted rat gut sac model showed IndOEt passage of 0.16 micromol m(-2) through the serosal fluid (30 min). From 15 to 120 min, the IndOEt concentrations in the tissue increased from 6.13 to 27.47 micromol m(-2). No IndOH was formed ex vivo. A fluorescent-NC formulation was used to determine the copolymer bioadhesion (0.012 micromol m(-2)). After NC-IndOEt oral administration to rats, IndOEt and IndOH were detected in the gastrointestinal tract (contents and tissues). In the tissues, the IndOEt concentrations decreased from 459 to 5 microg g(-1) after scrapping, demonstrating the NC mucoadhesion. In plasma (peripheric and portal vein), in spleen and liver, exclusively IndOH was detected. In conclusion, after oral dosing of NC-IndOEt, IndOEt is converted into IndOH in the intestinal lumen and wall before reaching the blood stream. The complexity of a living system was not predicted by the ex vivo gut sac model.

The search for new biomaterials intended for biomedical applications has considerably intensified in recent years. Herein, the synthesis and characterization of a new aliphatic biodegradable copolyester named PBS/PBDL (poly(butylene succinate-co-butylene dilinoleate)) is reported. Surfactant-free, narrowly distributed, nanosized spherical particles (RH < 60 nm) have been produced from the biodegradable material by applying a single-step nanoprecipitation protocol. Their structure was characterized in detail by employing a variety of scattering techniques and transmission electron microscopy (TEM). Combined SLS and DLS measurements suggested that the nanoparticles comprise a porous core conferring a non-compact characteristic. Their porosity enables water to be entrapped which is responsible for their pronounced stability and relatively fast degradation as followed by size exclusion chromatography (SEC). The polymeric nanoparticles could be loaded with the hydrophobic model drug paclitaxel (PTX) with an encapsulation efficiency of ∼95% and drug loading content of ∼6–7% wdrug/wpolymer. The drug release was followed by HPLC and scattering measurements (DLS, SLS and SAXS). The drug encapsulation and release modifies the inner structure of the nanoparticles, which holds a large amount of entrapped water in the drug-free condition. PTX encapsulation leads to replacement of the entrapped water by the hydrophobic model drug and to shrinking of the nanoparticles, probably due to favorable drug–polymer hydrophobic interactions. Cell viability experiments demonstrated that the nanoparticles are biocompatible and non-toxic, making them potentially useful for applications in nanomedicine.

The surface modification of nanoparticles by physically anchoring hydrophilic biocompatible polymers is a simple and commercially attractive strategy to produce stealth drug delivery nanocarriers. Herein, we report the preparation, characterization and preliminary evaluation of the biological behaviour of polymeric nanoparticles (NPs) comprising a biodegradable poly(butylene succinate-co-butylene dilinoleate) – PBS/PBDL – copolyester and a non-immunogenic and non-toxic hydrophilic N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer. Narrowly distributed sub-100 nm polymeric nanoparticles with stealth properties were successfully prepared by using a combination of interfacial nanoprecipitation and self-assembly. The assemblies were characterized by using complementary scattering techniques and cryo-transmission electron microscopy. The dimension of the NPs was found to be in the proper range to avoid fast renal clearance (DH > 10 nm) and still below the cut-off size of the leaky pathological microvasculature of hypervascular tumours (DH < 200 nm), thus making them candidates for application in cancer therapy based on the EPR effect. The presence of PHPMA copolymer exposed at the surface of the nanoparticles was confirmed by scattering measurements. The stealth property of the biocompatible and biodegradable NPs is responsible for their remarkable in vitro stability monitored in a simulated physiological environment and increased stability in concentrated NaCl solutions compared to uncoated PBS/PBDL nanoparticles, making them an alternative to PEG-shielded particles. Furthermore, a reproducible, efficient and satisfactory physical entrapment of the antitumoral drug doxorubicin (DOX) was achieved (∼5.0% wdrug/wNPs). The controlled DOX release is pH-dependent and faster under slightly acidic conditions and the cell viability experiments demonstrated that the drug-free NPs are non-toxic, whereas the DOX-loaded NPs exert in vitro cytostatic efficacy on EL4 T cell lymphoma.

The use of noble metal nanoparticles in biomedical and biotechnological applications is nowadays well established. Particularly, silver nanoparticles (AgNPs) were proven to be effective for instance as a biocide agent. They also find applications in tumor therapies and sensing applications being encouraging tools for in-vivo imaging. In this framework, whenever they are in contact with living systems, they are rapidly coated by a protein corona thereby influencing a variety of biological events including cellular uptake, blood circulation lifetime, cytotoxicity and, ultimately, the therapeutic effect. Taking these considerations into account, we have explored the behavior of polymer-coated AgNPs in model protein environments focusing on the self-development of protein coronas. The polymers polyethyleneimine (PEI), polyvinylpyrrolidone (PVP) and poly(2-vinyl pyridine)-b-poly(ethylene oxide) (PEO-b-P2VP) were used as stabilizing agents. The chemical nature of the polymer capping remarkably influences the behavior of the hybrid nanomaterials in protein environments. The PEO-b-P2VP and PVP-stabilized AgNPs are essentially inert to the model proteins adsorption. On the other hand, the PEI-stabilized AgNPs interact strongly with bovine serum albumin (BSA). Nevertheless, the same silver colloids were evidenced to be stable in IgG and lysozyme environments. The BSA adsorption into the PEI-stabilized AgNPs is most probably driven by hydrogen bonding and van der Waals interactions as suggested by isothermal titration calorimetry data. The development of protein coronas around the AgNPs may have relevant implications in a variety of biological events. Therefore, further investigations are currently underway to evaluate the influence of its presence on the cytotoxicity, hemolytic effects and biocide properties of the produced hybrid nanomaterials.