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In this study, functional Pluronic F127 precursors were designed and synthesized for the preparation of thermosensitive hydrogels. Using linear Pluronic thioacetate and Pluronic multi-acrylate precursors, F127-based hydrogels were prepared through thioacetate deprotection-mediated Michael-type addition. The properties of these gels were compared to those obtained through free radical crosslinking of F127 diacrylate. Temperature was found to have a clear influence on gel swelling as a result of F127 thermoresponsiveness. The macromolecular architecture and functionality of the precursors were also optimized and characterized in terms of gelation kinetics and drug diffusion. In vitro tests were conducted on fibroblasts and endothelial cells to assess their response to cellular adhesion with Pluronic gels that were functionalized with an RGD peptide or pretreated with serum proteins to promote cell adhesion. This study provides a method for creating tailored hydrogels suitable for various biomedical applications, such as soft-tissue engineering, cell encapsulation, wound healing, and sustained delivery of therapeutic molecules.

Diabetes mellitus is a worldwide-spread chronic metabolic disease that occurs when the pancreas fails to produce enough insulin levels or when the body fails to effectively use the secreted pancreatic insulin, eventually resulting in hyperglycemia. Systematic glycemic control is the only procedure at our disposal to prevent diabetes long-term complications such as cardiovascular disorders, kidney diseases, nephropathy, neuropathy, and retinopathy. Glycated albumin (GA) has recently gained more and more attention as a control biomarker thanks to its shorter lifespan and wider reliability compared to glycated hemoglobin (HbA1c), currently the "gold standard" for diabetes screening and monitoring in clinics. Various techniques such as ion exchange, liquid or affinity-based chromatography and immunoassay can be employed to accurately measure GA levels in serum samples; nevertheless, due to the cost of the lab equipment and complexity of the procedures, these methods are not commonly available at clinical sites and are not suitable to home monitoring. The present review describes the most up-to-date advances in the field of glycemic control biomarkers, exploring in particular the GA with a special focus on the recent experimental analysis techniques, using enzymatic and affinity methods. Finally, analysis steps and fundamental reading technologies are integrated into a processing pipeline, paving the way for future point-of-care testing (POCT). In this view, we highlight how this setup might be employed outside a laboratory environment to reduce the time from measurement to clinical decision, and to provide diabetic patients with a brand-new set of tools for glycemic self-monitoring.

A class of linear and four-arm mannosylated brush copolymers based on poly(ethylene glycol) and poly(ε-caprolactone) is presented here. The synthesis through ring-opening and atom transfer radical polymerizations provided high control over molecular weight and functionality. A post-polymerization azide–alkyne cycloaddition allowed for the formation of glycopolymers with different mannose valencies (1, 2, 4, and 8). In aqueous media, these macromolecules formed nanoparticles that were able to bind lectins, as investigated by concanavalin A binding assay. The results indicate that carbohydrate–lectin interactions can be tuned by the macromolecular architecture and functionality, hence the importance of these macromolecular properties in the design of targeted anti-pathogenic nanomaterials.

7 figures.-- Supplementary material available on line (6 figures).-- This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder., Carbon nanomaterials offer excellent prospects as therapeutic agents, and among them, graphene quantum dots (GQDs) have gained considerable interest thanks to their aqueous solubility and intrinsic fluorescence, which enable their possible use in theranostic approaches, if their biocompatibility and favorable pharmacokinetic are confirmed. We prepared ultra-small GQDs using an alternative, reproducible, top-down synthesis starting from graphene oxide with a nearly 100% conversion. The materials were tested to assess their safety, demonstrating good biocompatibility and ability in passing the ultrafiltration barrier using an in vitro model. This leads to renal excretion without affecting the kidneys. Moreover, we studied the GQDs in vivo biodistribution confirming their efficient renal clearance, and we demonstrated that the internalization mechanism into podocytes is caveolae-mediated. Therefore, considering the reported characteristics, it appears possible to vehiculate compounds to kidneys by means of GQDs, overcoming problems related to lysosomal degradation., J. M. G.-D. acknowledges Spanish Ministry of Science, Innovation and Universities for his Juan de la Cierva Incorporación research contract (No. IJCI-2016-27789). This project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Skłodowska-Curie Grant Agreement No. 734834 (INFUSION) and No. 734381 (CARBO-IMmap), and from MIUR. ICN2 is supported by the Severo Ochoa program from Spanish MINECO (No. SEV-2017-0706)., Funding note : Open Access funding provided by Università degli Studi di Trieste within the CRUICARE Agreement.

Well-defined amphiphilic PCL-PEG copolymers with complex molecular architectures were synthesized through a combination of Ring Opening Polymerization (ROP) and Atom Transfer Radical Polymerization (ATRP) and used to produce self-assembled nanoparticles for drug nanoencapsulation. By varying the functionality of the initiator used for the ATRP (i.e. linear, 4-armed or multifunctional brush macroinitiators), a library of comb-like and brush block copolymers were obtained with different structure, molecular weight, and number of PEG and PCL blocks. We investigated how these parameters influenced nanoparticle self-assembly in aqueous environment, as well as the ability to encapsulate and release hydrophobic therapeutic molecules. In particular, the hydrophobic corticosteroid dexamethasone, known as a therapeutic drug with anti-inflammatory and immunosuppressive effects, was chosen as a model. The results indicate that self-assembly, final particle size and drug loading can be tuned by designing a specific macromolecular architecture, which therefore represents a key feature for the design of efficient polymer nanocarriers for drug delivery.

In the continuous search for multimodal systems with combined diagnostic and therapeutic functions, several efforts have been made to develop multifunctional drug delivery systems. In this work, through a covalent approach, a new class of fluorinated poly(lactic-co-glycolic acid) co-polymers (F-PLGA) were designed that contain an increasing number of magnetically equivalent fluorine atoms. In particular, two novel compounds, F

The impact of protein therapeutics in healthcare is steadily increasing, due to advancements in the field of biotechnology and a deeper understanding of several pathologies. However, their safety and efficacy are often limited by instability, short half-life and immunogenicity. Nanodelivery systems are currently being investigated for overcoming these limitations and include covalent attachment of biocompatible polymers (PEG and other synthetic or naturally derived macromolecules) as well as protein nanoencapsulation in colloidal systems (liposomes and other lipid or polymeric nanocarriers). Such strategies have the potential to develop next-generation protein therapeutics. Herein, we review recent research progresses on these nanodelivery approaches, as well as future directions and challenges.

Free radical polymerization (FRP) is widely used in industrial processes as an efficient and versatile method to engineer polymeric nanoparticles (PNPs) of controlled size, narrowly distributed, and of well-defined surface properties. Functional Poly(e-caprolactone) (PCL) and poly(lactic acid) (PLA) can be utilized as macromonomers in FRP in combination with a co-polymerizable poly(ethylene glycol) (PEG), to achieve aqueous dispersions of PNPs composed of a hydrophobic polyester core and a hydrophilic PEG shell of tuneable size. For several industrial and biological applications, PNPs also need surface functionalization to provide specific physicochemical characteristics, including stimuli-responsiveness, and bioactivity. In this work, a flexible “grafting through” strategy based on Ring opening polymerization (ROP) and FRP was proposed to obtain engineered polyester-PEG nanoparticles functionalized with acrylate groups on the hydrophilic shell. The presence of acrylates allows a versatile surface functionalization through Michael-type addition with a thiolated ligand (peptide), in aqueous solution under physiological pH, with the advantage of high conversion and absence of reaction side products. A cysteine-containing cyclic RGD was used as model peptide for conjugation, due to its potential application as ligand for endothelial cells. Results indicated that active cell targeting can be achieved by using this surface functionalization approach.

We explored the use of new drug-loaded nanocarriers and their targeted delivery to the kidney glomerulus and in particular to podocytes, in order to overcome the failure of current therapeutic regimens in patients with proteinuric (i.e. abnormal amount of proteins in the urine) diseases. Podocytes are glomerular cells which are mainly responsible for glomerular filtration and are primarily or secondarily involved in chronic kidney diseases. Therefore, the possibility to utilise a podocyte-targeted drug delivery could represent a major breakthrough in kidney disease research, particularly in terms of dosage reduction and elimination of systemic side effects of current therapies. Four-arm star-shaped polymers, with/without a hydrophobic poly-ε-caprolactone core and a brush-like polyethylene glycol (PEG) hydrophilic shell, were synthesised by controlled/living polymerisation (ROP and ATRP) to allow the formation of stable ultrasmall colloidal nanomaterials of tuneable size (5-30nm), which are able to cross the glomerular filtration barrier (GFB). The effects of these nanomaterials on glomerular cells were evaluated in vitro. Nanomaterial accumulation and permeability in the kidney glomerulus were also assessed in mice under physiological and pathological conditions. Drug (dexamethasone) encapsulation was performed in order to test loading capacity, release kinetics, and podocyte repairing effects. The marked efficacy of these drug-loaded nanocarriers in repairing damaged podocytes may pave the way for developing a cell-targeted administration of new and traditional drugs, increasing efficacy and limiting side effects.

Thermosensitive liposomes are clinically-relevant nanocarriers which have been used to deliver chemotherapeutic agents to tumors in combination with local hyperthermia. However, the encapsulation and release of macromolecular therapeutic agents (proteins, nucleic acids, bioactive polymers) is often hindered by their instability during the liposome formation as well as by the low encapsulation efficiency. The objective of this study was to investigate the influence of the thermosensitive liposomal formulation on the encapsulation and release of low and high molecular weight hydrophilic drugs, in order to identify the key parameters to control during nanocarrier design, depending on the specific drug delivery application. Thermosensitive liposomes with different formulations were prepared through the combinations of different lipids, including dipalmitoylphosphatidylcholine (DPPC), distearoylphosphatidylcholine (DSPC), cholesterol (Chol), 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphocholine (P-Lyso-PC), and the PEGylated lipid distearoyl-sn-glycero-3-phosphoethanolamine-N-methoxy(PEG)-2000 (DSPE-PEG2000). The thin film hydration method was used for liposome preparation and loading of different water soluble molecules. The encapsulation efficiency and release profiles were investigated for a low molecular weight compound such as carboxyfluorescein (CF), proteins (albumin), and hydrophilic polymers which do not interact with the lipid bilayer, such as a linear dextran and a poly(ethylene glycol)-based star polymer. An optimised liposomal formulation [DPPC/P-lyso-PC/DSPE-PEG2000 90/10/4 (mol/mol) (LTSL)] was chosen for further application in encapsulating therapeutic proteins, such as lysozyme and the brain-derived neurotrophic factor (BDNF), which are recognized as drug carriers and potential therapeutic agents for kidney diseases and neurological disorders.

Specific therapeutic targeting of kidney podocytes, the highly differentiated ramified glomerular cells involved in the onset and/or progression of proteinuric diseases, could become the optimal strategy for preventing chronic kidney disease. With this aim, we developed a library of engineered polymeric nanoparticles (NPs) of tuneable size and surface properties and evaluated their interaction with podocytes. NP cytotoxicity, uptake, and cytoskeletal effects on podocytes were first assessed. On the basis of these data, nanodelivery of dexamethasone loaded into selected biocompatible NPs was successful in repairing damaged podocytes. Finally, a three-dimensional in vitro system of co-culture of endothelial cells and podocytes was exploited as a new tool for mimicking the mechanisms of NP interaction with glomerular cells and the repair of the kidney filtration barrier., ACS Omega, 2 (2), ISSN:2470-1343

Fluorinated hyperbranched polyether copolymers of tuneable composition and architecture were designed and synthesized to develop drug nanocarriers as well as 19F MRI contrast agents. The performance of these nanomaterials in terms of nanoparticle formation and drug (dexamethasone) loading, as well as 19F-MRI detectability, was evaluated. These polymers were obtained through controlled ring opening multibranching polymerisation, and the presence of pendant fluorinated groups was obtained by copolymerisation of glycidol and the fluorinated glycidyl ether 2-[(2,2,2-trifluoroethoxy)methyl]oxirane. By varying polymer composition and architecture during the synthesis, we controlled the key properties of the nanomaterials, including the fluorine content, drug loading, nanoparticle size, and MRI signal. The macromolecules were cytocompatible, with the ability to deliver dexamethasone on damaged kidney glomerular cells in vitro; therefore they hold promise as new generation 19F MRI nanotheranostics.

In the continuous search for multimodal systems with combined diagnostic and therapeutic functions, several efforts have been made to develop multifunctional drug delivery systems. In this work, through a covalent approach, a new class of fluorinated poly(lactic-co-glycolic acid) co-polymers (F-PLGA) were designed that contain an increasing number of magnetically equivalent fluorine atoms. In particular, two novel compounds, F3 -PLGA and F9 -PLGA, were synthesized and their chemical structure and thermal stability were analyzed by solution NMR, DSC, and TGA. The obtained F-PLGA compounds were proven to form in aqueous solution colloidal stable nanoparticles (NPs) displaying a strong 19 F NMR signal. The fluorinated NPs also showed an enhanced ability to load hydrophobic drugs containing fluorine atoms compared to analogous pristine PLGA NPs. Preliminary in vitro studies showed high cell viability and the NP ability to intracellularly deliver and release a functioning drug.

The presence of circulating permeability factors (cPFs) has been hypothesized to be associated with recurrence of focal segmental glomerulosclerosis (rFSGS) in renal allografts. The available methods to detect cPFs are complex, not easily repeatable and inappropriate to represent the anatomical characteristics of the three-layer glomerular filtration barrier (GFB). Here we describe a novel method which measures the permeability to bovine serum albumin (BSA) through a three-layer device (3LD). The 3 layers comprise: (1) conditionally immortalized human podocytes (HCiPodo), (2) collagen type IV coated porous membrane and (3) human glomerular endothelial cells (HCiGEnC). Using this method, we found that sera from all rFSGS patients increased albumin permeability, while sera from non recurrent (nrFSGS) and genetic (gFSGS) forms of FSGS did not. The mechanisms underlying the increase of albumin permeability are probably due to endothelial cell damage as an initial event, which was demonstrated by the decrease of Platelet endothelial cell adhesion molecule (PECAM-1 or CD31), while the podocytes’ expressions of synaptopodin and podocin were normal. Furthermore, we also found that the plasmapheretic treatment (PPT) eliminated the effect of increasing BSA permeability in sera from rFSGS patients. These preliminary data suggest that our in vitro GFB model could not only be useful in predicting the recurrence of FSGS after renal transplantation (RTx), but also be a valuable in vitro model to study podocyte and endothelial cell biology.

Unimolecular polymeric micelles are a class of single-molecule amphiphilic core-shell polymeric architectures, where the hydrophobic core is well stabilized by the hydrophilic shell, avoiding intermolecular core-core interactions. Multi-arm copolymers with a dendritic core, as well as hyperbranched and comb-like polymers, can form unimolecular micelles easily. In this review, examples of polymers able to form detectable unimolecular micelles will be presented, summarizing the analytical techniques used to characterize the unimolecular micelles and discriminate them from other supramolecular aggregates, such as multi-micelle aggregates. Unimolecular micelles are suitable for the nanoencapsulation of guest molecules. Compared to traditional supramolecular micelles, unimolecular micelles do not disassemble under dilution and are stable to environmental modifications. Recent examples of their application as drug delivery systems, endowed with increased stability and transport properties, will be discussed.

This study is about the use of β-glycerophosphate (βGP) to modulate the production of chitosan microparticles through a technology of jet break-up. βGP has been described as capable of producing chitosan gels without additional complexing agents via a thermal transition (inverse gelation). A preliminary assessment on the effect of temperature on the viscosity and gelation of chitosan/βGP precursors demonstrated that the crosslinking process was too slow to afford microparticle production via jet break-up. Instead, βGP was used as a solubilizer to provide stable chitosan solution at neutral pH, which allowed the preparation of microparticles through polyelectrolyte complexation (with triphosphate) under physiological conditions, as opposed to the more conventional method of chitosan solubilisation in acids. Here, the key parameters of the microencapsulation process have been optimized, aiming to produce spherical particle of well-defined size and circularity, as well as toroidal microparticles, with a physico-chemical evaluation of the products.

A versatile approach is proposed for the synthesis of novel immunoactive nanomaterials based on biocompatible poly(glycerol monomethacrylate) (PGMMA). Propargyl-terminated PGMMA is synthesized via atom transfer radical polymerization and then modified through the introduction of dangling acrylate groups, at controlled degree of functionalisation. Acrylates are then able to react quantitatively with thiols, such as immunoactive thiomannose, through Michael-type addition under mild conditions and at a physiologically acceptable pH. The terminal propargyl group can be modified independently with azide end-capping groups and it is utilized to graft the macromolecules to a fluorescent dye. The resulting mannose-linked PGMMAs confirm a safe cytotoxic profile and are able to stimulate cytokine production (TNFα), membrane protein expression (CD40), and cellular uptake in bone marrow derived dendritic cells. Cell stimulation is dependent on the mannose content and enhanced by serum proteins, suggesting a role for mannose-binding receptors and/or complement receptors in the cell membrane.

We explored a versatile enzyme nanoencapsulation process based on the synthesis of silica gel nanoparticles, decorated with a dense hydrophilic poly(glycerol monomethacrylate) (PGMMA) shell for biological and therapeutic applications. These hybrid enzyme-SiO2-polymer nanoparticles were obtained through an aqueous sol-gel process, followed by the adsorption of cationic macroinitiators by electrostatic complexation. Surface-initiated Atom Transfer Radical Polymerisation (ATRP) was applied to obtain a dense hydrophilic (protein repellent) PGMMA layer of tunable size, under conditions which are compatible with the nanoencapsulation of horseradish peroxidase. The sol-gel synthetic procedure, the composition and molecular weight of the macroinitiators, the polymer adsorption and purification methods, and the final ATRP conditions, were optimised to control the properties of these nanoparticles, in terms of particle size, Z-potential, PGMMA decoration, while preserving enzymatic activity.

This study presents a quantitative assessment of the complexation between boronic acids and diols as a reversible and double-stimulus (oxidation and acidification)-responsive bioconjugation reaction. First, by using a competition assay, we have evaluated the equilibrium constants (water, pH 7.4) of 34 boronate/diol pairs, using diols of both aliphatic and aromatic (catechols) nature; in general, catechols were characterized by constants 3 orders of magnitude higher than those of aliphatic diols. Second, we have demonstrated that successful complexation with diols generated in situ via enzymatic reactions, and the boronate complexation was also employed to calculate the Michaelis-Menten parameters for two catechol-producing reactions: the demethylation of 3-methoxytyramine and the 2-hydroxylation of estradiol, respectively, mediated by P4502D6 and P4501A2. Third, we have prepared phenylboronic acid-functionalized hyaluronic acid (HA) and demonstrated the pH and H2O2-responsive character of the adducts that it formed with Alizarin Red S (ARS) used as a model catechol. The versatility and selectivity of the complexation and the mild character of the chemical species involved therefore make the boronate/catechol reaction an interesting candidate for bioconjugation purposes.

Tumor-homing peptides have been exploited to create nanocarriers for targeted delivery of therapeutic agents to the placenta., The availability of therapeutics to treat pregnancy complications is severely lacking mainly because of the risk of causing harm to the fetus. As enhancement of placental growth and function can alleviate maternal symptoms and improve fetal growth in animal models, we have developed a method for targeted delivery of payloads to the placenta. We show that the tumor-homing peptide sequences CGKRK and iRGD bind selectively to the placental surface of humans and mice and do not interfere with normal development. Peptide-coated nanoparticles intravenously injected into pregnant mice accumulated within the mouse placenta, whereas control nanoparticles exhibited reduced binding and/or fetal transfer. We used targeted liposomes to efficiently deliver cargoes of carboxyfluorescein and insulin-like growth factor 2 to the mouse placenta; the latter significantly increased mean placental weight when administered to healthy animals and significantly improved fetal weight distribution in a well-characterized model of fetal growth restriction. These data provide proof of principle for targeted delivery of drugs to the placenta and provide a novel platform for the development of placenta-specific therapeutics.

The delivery of living cells into a host body has emerged as a promising approach to treating a variety of different diseases and for tissue repair. However, one of the major obstacles for clinical success is to deliver the cells to the target tissue without losing control of cell fate and function after transplantation. Temperature-responsive biomaterials represent a promising vehicle to deliver cells noninvasively by injection of a liquid precursor, which undergoes a reversible phase transition at body temperature, thus, forming temperature-induced hydrogels in situ. The final material provides transplanted cells with a synthetic extracellular matrix, which retains the cells at the injection site, supports cell growth and mitigates migration. This mini review is intended to cover the fundamental physicochemical characteristics of these thermoresponsive biomaterials, and to examine the applications, with a focus on the recently developed cell-delivery systems for tissue engineering and cell therapy, including advantages, limitations and future challenges.

Purpose This study aims to address the lack of independent subjective efficacy data on artificial tear substitutes in the treatment of dry eye due to the anecdotal association of ‘thicker’ products being more effective. Methods This is an independent study of the subjective use and efficacy of topical treatments used by members of the British Sjogren's Syndrome Association (BSSA) related to product viscosity. 2000 members of the BSSA were sent a questionnaire regarding their physical condition and the use of artificial tear substitutes. Viscosity analysis was performed on the most popular preparations. Statistical comparison is made between subjective efficacies related to substitute tear viscosity. Results 1088 patients responded giving information regarding their condition together with the subjective use and efficacy data of artificial tear substitutes. Visco-analysis was performed on the most popular preparations; these had more than 50 patients using them. In terms of subjective benefits related to viscosity for ‘frequency’ and ‘duration’ the data suggests a general trend toward viscous preparations being instilled less frequently and lasting longer; however this was not shown to be significantly correlated and some interesting comparisons are reported. Conclusions The results confirm high levels of ocular lubricant use in the BSSA population. Our data investigates the often-anecdotal evidence that thicker preparations are more effective. However, we did not find this correlation to be statistically significant suggesting further study into factors related to subjective product efficacy. These results lay foundations for the development of future products in the treatment of severe dry eye.

pH-responsive microgels are crosslinked polymer colloids that swell when the pH approaches the pK a of the particles. They have potential application for injectable gels for tissue repair and drug delivery systems. This study focuses on the pH-triggered gelation behaviour of a series of poly (EA/MAA/X) microgels. EA and MAA are ethylacrylate and methacrylic acid. Here, we investigate the effect of crosslinking monomer type (X) on microgel properties. The crosslinking monomers used were poly (ethyleneglycol) dimethacrylate (PEGD), ethyleneglycol dimethacrylate (EGD) and butanediol diacrylate (BDD). The microgel containing PEGD (m-PEGD) is a new system. The microgel containing BDD (m-BDD) was used as a control system. The concentrated microgel dispersions formed physical gels when the pH was increased to 5.3–6.7, and the polymer volume fractions (ϕ p ) were above about 0.05. Evidence from photon correlation spectroscopy (PCS) and dynamic rheology was presented for abrupt pH-triggered increases, and then decreases of the hydrodynamic diameters for m-PEGD and the microgel prepared using EGD (m-EGD). This appears to be tuneable through crosslinker structure. An unexpected gelation behaviour, which may involve a new gel state for microgels, was found for m-PEGD dispersions. Uniquely, those dispersions formed gels at pH values less than the microgel's pK a . This behaviour was linked to an outer-shell electrostatic repulsive interaction. The data point to a phenomenon, whereby the m-PEGD shells appear to explode at pH values above 7.0. The control microgel prepared, using BDD (m-BDD), did not show any evidence of shell fragmentation at any pH. That microgel has potential as a model pH-responsive microgel system in that the properties measured by PCS and rheology agreed well. To probe that system in more detail, the rheological data for m-BDD was analysed using scaling theory. The variation of the storage modulus (G') with ϕ p gave a scaling exponent of 2.0.

Colloidal hybrids comprise organic and inorganic components and are attracting considerable attention in the literature. Recently, we reported hybrid anisotropic microsheets that formed thermoresponsive gels in polymer solutions [Liu et al., Langmuir, 25, 490, 2009]. Here, we investigate the composition and properties of these hybrid colloids themselves in detail for the first time. Three different cationic PNIPAm (N-isopropylacrylamide) graft copolymers and two inorganic nanoparticle types (laponite and Ludox silica) were used to prepare a range of hybrids. Anisotropic microsheets only formed when laponite particles were added to the copolymer implying directed self-assembly. Aqueous dispersions of the microsheets spontaneously formed gels at room temperature and these gels were thermoresponsive. They represent a new class of gel forming colloid and are termed thermoresponsive gel forming hybrids. The compositions of the hybrids were determined from thermogravimetric analysis and those that gave gel forming behaviour identified. Variable-temperature rheology experiments showed that the elasticity of the gels increased linearly with temperature. The reversibility of the thermally-triggered changes in gel elasticity was investigated. The concentration dependence of the rheology data was well described by elastic percolation scaling theory and the data could be collapsed onto a master curve. The concentration exponent for the elastic modulus was 2.5. The strong attractive interactions that exist between the dispersed gel forming hybrids was demonstrated by the formation of stable thermoresponsive hybrid hydrogels through casting of hybrid dispersions.

In this work, temperature-triggered gelation of aqueous laponite dispersions containing a cationic poly(N-isopropylacrylamide) (PNIPAm) graft copolymer was investigated. The copolymer used was PDMA(+)(30)-g-(PNIPAm(210))(14) [Liu et al. Langmuir 2008, 24, 7099]. DMA(+) is quarternarized N,N-dimethylaminoethyl methacrylate. The presence of small concentrations of laponite enabled temperature-triggered gel formation to occur at low copolymer concentrations (e.g., 1 wt %). Dynamic rheological measurements of the gels showed that they had storage modulus values of up to 400 Pa when the total solid volume fraction (polymer and laponite) was only about 0.02. The storage modulus was dependent on both the temperature and the composition of the dispersion used for preparation. The key component that provided the temperature-triggered gels with their elasticity was found to be self-assembled nanocomposite (NC) sheets. These NC sheets spontaneously formed at room temperature upon addition of laponite to the copolymer solution. The NC sheets had lateral dimensions on the order of hundreds of micrometers and a thickness of a few micrometers. The NC sheets were present within the temperature-triggered gels and formed elastically effective chains. The NC sheets exhibited temperature-triggered contraction with a contraction onset temperature of 27 degrees C. A conceptual model is proposed to qualitatively explain the relationship between gel elasticity and dispersion composition.

In this work temperature-triggered association and gel formation within aqueous solutions of a new family of cationic poly( N-isopropyl acrylamide) (PNIPAm) graft copolymers have been investigated. Five copolymers were synthesized using aqueous atom transfer radical polymerization (ATRP) involving a macroinitiator based on quaternarized N, N-dimethylaminoethyl methacrylate units (DMA+). The PDMA+) x - g-(PNIPAmn)y copolymers have x and y values that originate from the macroinitiator; values for n correspond to the PNIPAm arm length. The copolymer solutions exhibited temperature-triggered formation of nanometer-sized aggregates at the cloud point temperature, which was 33-34 degrees C. The aggregates were investigated using variable-temperature turbidity, hydrodynamic diameter, and electrophoretic mobility measurements. The aggregates were clearly evident using SEM and flowerlike or spherical morphologies were observed. Variable-temperature electrophoretic mobility measurements revealed that the zeta potentials of the aggregates increased with DMA+ content. A study of the effect of added NaNO3 showed that electrostatic interactions controlled the size of the aggregates. The concentrated graft copolymer solutions showed temperature-triggered gelation when the copolymer concentrations exceeded 5 wt %, Fluid-to-gel phase diagrams were constructed. It was found that electrostatic interactions also controlled the gelation temperature. A correlation was found between aggregate size and the minimum copolymer concentration needed to form a gel. A mechanism for the temperature-triggered structural changes leading to the formation of aggregates (in dilute solution) or gels (in concentrated solutions) is proposed.

We here present a new method for preparing ligand-free titania nanoparticles, which are easily amenable to surface functionalization in an aqueous environment. The specific advantage of this method is that it combines the advantages of nonaqueous synthetic processes (high crystallinity) to those of a surface functionalization in a water medium, which allows for a wider variety of biofunctional (and nonorganic-soluble) groups to be added on the nanoparticles. In particular, we report on the characterization of the three phases of synthesis, dispersion in water environment and surface functionalization of the nanoparticles, focusing on a qualitative evaluation of the surface adsorption mechanism.

Proteinuria is a common symptom of glomerular diseases and is due to leakage of proteins from the glomerular filtration barrier, a three-layer structure composed by two post-mitotic highly specialized and interdependent cell populations, i.e. glomerular endothelial cells and podocytes, and the basement membrane in between. Despite enormous progresses made in the last years, pathogenesis of proteinuria remains to be completely uncovered. Studies in the field could largely benefit from an in vitro model of the glomerular filter, but such a system has proved difficult to realize. Here we describe a method to obtain and utilize a three-dimensional podocyte-endothelial co-culture which can be largely adopted by the scientific community because it does not rely on special instruments nor on the synthesis of devoted biomaterials. The device is composed by a porous membrane coated on both sides with type IV collagen. Adhesion of podocytes on the upper side of the membrane has to be preceded by VEGF-induced maturation of endothelial cells on the lower side. The co-culture can be assembled with podocyte cell lines as well as with primary podocytes, extending the use to cells derived from transgenic mice. An albumin permeability assay has been extensively validated and applied as functional readout, enabling rapid drug testing. Additionally, the bottom of the well can be populated with a third cell type, which multiplies the possibilities of analyzing more complex glomerular intercellular signaling events. In conclusion, the ease of assembly and versatility of use are the major advantages of this three-dimensional model of the glomerular filtration barrier over existing methods. The possibility to run a functional test that reliably measures albumin permeability makes the device a valid companion in several research applications ranging from drug screening to intercellular signaling studies.

The classical sol–gel synthesis of silica gels has been adapted to a W/O (micro)emulsion process under conditions that minimize denaturing effects on encapsulated enzymes. We have in particular focused on optimizing the purification procedures with the aim to produce water nanoparticles dispersions from W/O emulsions without the use of precipitation/sedimentation steps. A proof of principle of encapsulation has been conducted using horseradish peroxidase (HRP).

[Chemical structure: see text] The interactions between a biomaterial and biomolecules present in body fluids often determine the fate of the biomaterial. This paper presents a study on hyaluronan (HA)-containing materials (in soluble or colloidal form) that focuses on their interactions with lipids and proteins and for the first time uses PFG NMR as an analytical technique for probing these events. The interactions of HA-based polymers with phospholipids (DPPC and DPPG liposomes) are shown to depend both on charge and hydrophobicity factors. Despite the difference in behavior between albumin (substantially non-adhesive) and fibrinogen (adhesive), the interactions of the polymers with proteins do not seem to be based on hydrophobic effects but on surface polar interactions.

We have previously described a gelation process based on the occurrence of both physical and a chemical mechanisms ('tandem process'), in which a telechelic linear poly(propylene glycol)-bl-poly(ethylene glycol)-bl-poly(propylene glycol) is first thermally gelled and subsequently covalently cross-linked by the reaction of polymer end groups at the termini of the copolymer. The quick kinetics of the reverse thermal gelation and the harmless character of the Michael-type addition between two sets of terminal groups, acrylates on one set and thiols on the other, allows irreversibly cross-linked hydrogels to be obtained in a rapid and biocompatible fashion, even when gelation was conducted in direct contact with cells. This allows in principle for an application of the tandem process in cell encapsulation. In the present work, we have optimized the macromolecular architecture and functionality of the precursors for allowing the use of the tandem process in encapsulation devices designed for calcium alginate. The mechanical, diffusional and biocompatibility properties of these materials were characterized; the comparison of mass transport properties of the tandem gels with those of calcium alginate suggests a similar or even better immunoisolation effect.

Podocytes are the main gatekeeper of protein filtration in the glomerulus. When podocytes work less efficiently, this translates to the appearance of proteins in the urine, a condition that, if not promptly treated, leads to progression of glomerular damage and renal failure.Novel gene mutations have been uncovered in patients with nephrotic syndrome combined with a better definition of the role of podocin mutations. Although the importance of the inflammasome pathway and of the mechanisms of autophagy in podocyte health and disease have been increasingly recognized, a precise relationship between these processes still needs to be assessed. Numerous potential therapeutic targets have been identified and numerous data support the possibility of boosting podocyte regeneration. However, translation of experimental results into the clinic could largely depend on the avoidance of undesired side-effects; nanomedicine could provide the means to target old and novel drugs specifically to the podocytes.Podocytes are key cells in the glomerulus, and their damage inevitably leads to proteinuria and glomerular dysfunction. The more is known about the causes and mechanisms of podocyte damage, the more it will be possible to find new cures for glomerular diseases of the kidney.

Non-aqueous routes to inorganic nanoparticles are supposedly based on the absence of water; here, this view is partially challenged, showing that the presence of water (or moisture) is probably necessary, and is surely useful to achieve a precise control over the growth/aggregation phenomena leading to titanium dioxide nanoparticles. This study is focused on the preparation of size-controlled and ligand-free titania (anatase) nanoparticles in water dispersion. This is achieved through a three-step process: 1) production of primary (3–4 nm) nanoparticles from titanium alkoxides (Ti(OnPr)4, Ti(OnBu)4 or Ti(OiPr)4) in benzyl alcohol through the controlled addition of water; 2) thermal growth phase, where the aggregation of primary nanoparticles at 80 °C leads to secondary nanoparticles with a typical fractal dimension of 2.2–2.4; the primary particles are still identifiable as the individual crystallites composing the secondary nanoparticles; 3) precipitation/re-dispersion in water, where secondary nanoparticles further agglomerate to yield tertiary nanoparticles. The size of the latter and their photocatalytic efficiency is primarily controlled by the nature of residual alkoxide chains; in particular, isopropoxide groups allow to produce anatase nanoparticles with an average size of 7–8 nm in water dispersion and in the absence of any stabilizing ligand, which is an unprecedented result.