Preformed Polymer Research Articles

Cryo-EM structure of the human native plasma coagulation Factor XIII complex

The structure of human coagulation factor XIII (FXIII), a heterotetrameric plasma pro-transglutaminase that covalently crosslinks pre-formed fibrin polymers, remains elusive until today. The heterotetrameric complex is composed of two catalytic FXIII-A and two protective FXIII-B subunits. Structural etiology underlying FXIII deficiency has so far been derived from crystallographic structures, all of which are currently available for the FXIII-A2 homodimer only. Here, we present the cryo-electron microscopy structure of a native, human plasma-derived FXIII-A2B2 complex at 2.4 Å resolution. The structure provides detailed information on FXIII subunit interacting interfaces as the two subunits interact strongly in plasma. The native FXIII-A2B2 complex reveals a pseudo-symmetric heterotetramer of two FXIII-B monomers intercalating with a symmetric FXIII-A2 dimer forming a "crown-like" assembly. The symmetry axes of the A2 and B2 homodimers are twisted relative to each other such that Sushi domain 1 interacts with the catalytic core of the A subunit and Sushi domain 2 with the symmetry related A' subunit and vice versa. We also report four novel mutations in the F13A1 gene encoding the FXIII-A subunit from a cohort of patients with severe FXIII deficiency. Our structure reveals the etiological basis of homozygous and heterozygous pathogenic mutations and explains the conditional dominant negative effects of heterozygous mutations. This atomistic description of complex interfaces is consistent with previous biochemical data and shows a congruence between the structural biochemistry of the FXIII complex and the clinical features of FXIII deficiency.

Block Copolymers‐Enabled Organic–Organic Assembly for Unique Carbonaceous Micro‐/Nano‐Structures

AbstractOver the past decade, there has been growing research interest in deriving advanced carbonaceous materials with unique architectures, including diverse morphologies and compositions, from polymer‐based precursors with tailored nano/micro‐structures. The organic–organic assembly between organic molecules and block copolymers (BCPs) has emerged as a promising strategy for advancing the preformed polymers with multiple levels of complexity. This review provides a comprehensive overview of the synthesis and potential applications of unique carbonaceous nano/micro‐structures derived from commonly used organic precursors, including phenol/formaldehyde, dopamine, and biomass. It begins with a brief summary of the polymerization mechanism for each type of precursors. Following this, it details the delicate design and preparation strategies for unique polymer architectures, including the formation mechanisms of the first‐level assembly involving BCPs and organic precursors, which form composite micelles as building units, and the principles for manipulation the higher‐level assembly process of the composite micelles, illustrated with some representative examples. The review then highlights the advanced applications of these materials in heterogeneous catalysts, secondary batteries, separation, and intelligent drug delivery systems. Finally, the synthetic challenges and potential development directions of unique carbonaceous nano/micro‐structures are outlined, underscoring a pathway for developing advanced materials.

Simultaneous and in situ syntheses of an enantiomeric pair of homochiral polymers as their perfect stereocomplex in a crystal

Circumventing the issues of conventional stereocomplexation of preformed polymers, herein, we synthesize two enantiopure polymers of opposite chirality simultaneously and in situ as their 1:1 stereocomplex via topochemical polymerization. We design and synthesize an inositol-based achiral monomer for topochemical ene-azide cycloaddition (TEAC) polymerization. In the crystal, the monomer exhibits conformational enantiomerism, and its conformational enantiomers are self-sorted in an arrangement for TEAC polymerization to yield two enantiopure polymers of opposite chirality. Upon heating the monomer crystals, each self-sorted set of conformational enantiomers undergoes regio- and stereospecific polymerization in a single-crystal-to-single-crystal fashion, generating two 1, 4-triazolinyl-linked polymers of opposite chirality simultaneously. The new chiral carbons in all the triazoline rings of a particular polymer chain have the same absolute configuration. These homochiral polymer strands align parallelly, forming a layer, and such enantiopure layers of opposite chirality stack alternately, forming a perfect 1:1 stereocomplex, which we confirmed using single-crystal XRD analysis.

Efficacy and safety of a 0.05 % nanoencapsulated imiquimod hydrogel for the treatment of actinic cheilitis: Drug release analysis and clinical study

Actinic cheilitis (AC) is a lip disorder, with no standard treatment. Imiquimod (IMIQ) is an immunomodulator that treat precancerous lesions; however, its commercial form causes severe adverse effects. This study aimed to assess IMQ release from a chitosan hydrogel containing 0.05 % nanoencapsulated (NANO) imiquimod (IMIQ-0.05 %-NANO) and its efficacy in AC treatment. The hydrogels were prepared by incorporating chitosan into polymeric nanocapsules (NCimiq) loaded with IMQ, produced using the interfacial deposition of preformed polymer method. IMQ release was evaluated using automated Franz Cells. A triple-blind randomized controlled trial (49 subjects) compared the efficacy of: IMIQ-0.05 %-NANO, 5 % free imiquimod (IMIQ-5 %), 0.05 % free imiquimod (IMIQ-0.05 %), and placebo hydrogel. The IMIQ-NANO-0.05 % and IMIQ-5 % groups exhibited significantly higher rates of clinical improvement (p < 0.05); however, the IMIQ-5 % group experienced more adverse effects (92.3 % of subjects) compared to other groups (p < 0.05). In conclusion, in the studied sample, IMIQ-NANO-0.05 % was a safe and effective option to treat AC.

Development of 3D skin equivalents for application in photodynamic biostimulation therapy assays using curcumin nanocapsules

For decades, animal models have been the standard approach in drug research and development, as they are required by regulations in the transition from preclinical to clinical trials. However, there is growing ethical and scientific concern regarding these trials, as 80 % of the therapeutic potential observed in pre-clinical studies are often unable to be replicated, despite demonstrating efficacy and safety. In response to this, Tissue Engineering has emerged as a promising alternative that enables the treatment of various diseases through the production of biological models for advanced biological assays or through the direct development of tissue repairs or replacements. One of the promising applications of Tissue Engineering is the development of three-dimensional (3D) models for in vitro tests, replacing the need for in vivo animal models. In this study, 3D skin equivalents (TSE) were produced and used as an in vitro model to test photobiostimulation using curcumin-loaded nanocapsules. Photodynamic biostimulation therapy uses photodynamic processes to generate small amounts of reactive oxygen species (ROS), which can activate important biological effects such as cell differentiation, modulation of inflammatory processes and contribution to cell regeneration. The PLGA nanocapsules (NC) used in the study were synthesized through a preformed polymer deposition method, exhibiting particle size <200 nm, Zeta potential >|30| and polydispersity index between 0.5 and 0.3. Atomic force microscopy analyzes confirmed that the particle size was <200 nm, with a spherical morphology and a predominantly smooth and uniform surface. The NC biocompatibility assay did not demonstrate cytotoxicity for the concentrations tested (2.5–25 μg mL−1).The in vitro release assay showed a slow and sustained release characteristic of the nanocapsules, and cellular uptake assays indicated a significant increase in cellular internalization of the curcumin-loaded nanostructure. Monolayer photobiostimulation studies revealed an increase in cell viability of the HDFn cell line (viability 134 %–228 %) for all LED fluences employed at λ = 450 nm (150, 300, and 450 mJ cm−2). Additionally, the scratch assays, monitoring in vitro scar injury, demonstrated more effective effects on cell proliferation with the fluence of 300 mJ cm−2. Staining of TSE with hematoxylin and eosin showed the presence of cells with different morphologies, confirming the presence of fibroblasts and keratinocytes. Immunohistochemistry using KI-67 revealed the presence of proliferating cells in TSE after irradiation with LED λ = 450 nm (150, 300, and 450 mJ cm−2).

Polymeric Nanocapsules Containing Ozonated Oil and Terbinafine Hydrochloride as a Potential Treatment Against Dermatophytes.

Terbinafine hydrochloride is a synthetic allylamine whose mechanism of action consists of inhibiting the enzyme squalene epoxidase that participates in the first stage of ergosterol synthesis, interfering with fungal membrane function. Ozonated oils are used for topical application of ozone, producing reactive oxygen species that cause cellular damage in microorganisms, therefore being an alternative treatment for acute and chronic skin infections. This study aimed to develop and characterize Eudragit® RS100 nanocapsules, obtained by interfacial deposition of preformed polymer method, containing 0.5% terbinafine hydrochloride and 5% ozonated sunflower seed oil as a potential treatment against dermatophytes. The polymeric nanocapsules were characterized regarding particle size, zeta potential, pH, drug content, encapsulation efficiency, and stability. The in vitro drug release, in vitro skin permeation, and in vitro antifungal activity were also evaluated. The particle size was around 150nm with a narrow size distribution, the zeta potential was around + 6mV, and the pH was 2.2. The drug content was close to 95% with an encapsulation efficiency of 53%. The nanocapsules were capable to control the drug release and the skin permeation. The in vitro susceptibility test showed greater antifungal activity for the developed nanocapsules, against all dermatophyte strains tested, compared to the drug solution. Therefore, the polymeric nanocapsules suspension containing terbinafine hydrochloride and ozonated oil can be considered a potential high-efficacy candidate for the treatment of dermatophytosis, with a possible reduction in the drug dose and frequency of applications. Studies to evaluate safety and efficacy in vivo still need to be performed.

Development and Application of Polymer Plugging Remover for Polymer Injection Well in Changqing Oilfield

Water injection is a conventional method to maintain reservoirs pressure and improve production in low permeability oilfield. To decrease high water-cut and further enhance oil recovery, Polymers, such as polymer microsphere, preformed polymer gel, cross-linked polyacrylamide, are extensively used to control injection profile in Changqing oilfield. However, due to the low permeability and narrow pore throats of tight reservoirs, pressure in some water flooding wells increases rapidly after the polymer was injected, negatively affecting the energy supplement of the well cluster. A polymer plugging remover, composed of oxidizer, acid and chelating agent to relieve blockage, was developed with viscosity reduction and structure decomposition. The release period is more than 48 hours, which is conducive to deep-seated plugging removal. After treatment, the average diameter of polymer residue is 39-254nm and the dissolution rate is 15.76-53.42%. The permeability of the core sample plugged with polymer has increased significantly before and after treatment by polymer plugging remover, especially, it recovered by 28.67% for microsphere polymer. Five field tests have been completed successfully in the Jiyuan oilfield of Changqing. Before treatment, conventional acidification was performed in the pilot wells for two times at least, which is proved invalid. However, after polymer degraded by the plugging remover, the injection rate increased by 16.2m3/d, the pressure dropped by 3.4MPa and the validity period has exceeded 130 days on average. The polymer plugging remover provides an alternative way to increase injectability when dealing with high pressure and under-injection wells caused by polymer flooding.

Controlled drug delivery from metronidazole-containing bioactive endodontic cements.

This study aims to formulate metronidazole liquid nanocapsules (MTZLNC) and evaluate their effect on the physicochemical and biological properties of calcium silicate-based bioactive endodontic cements, in vitro. A MTZLNC suspension was formulated by deposition of the preformed polymer and characterized by laser diffraction and high-performance liquid chromatography (HPLC). Calcium silicate (CS) was mixed with a radiopaque agent (calcium tungstate - CaWO4), at 10wt%, to produce the cement powder. Cements liquids were used with two concentrations of MTZLNC suspension: 0.3mg/ml and 0.15mg/ml. Cements prepared with distilled water were used as the control. The radiopacity, setting time, and flow were evaluated following ISO 6876:2012. The compressive strength analysis was conducted according to ISO 9917:2007. pH and mineral deposition were evaluated after immersion in simulated body fluid (SBF). Cell behavior was evaluated by the viability of pre-osteoblastic cells and pulp fibroblasts by SRB and MTT and the antibacterial activity against Enterococcus faecalis was analyzed immediately and after nine months of water storage. MTZLNCs were formulated with a median diameter of 148nm and 83.44 % load efficiency. Increased flow and reduced strength were observed for both MTZLNCs concentrations. The incorporation of MTZLNCs maintained the ability of cements to increase pH media and promote mineral deposition over the samples, without promoting cytotoxicity. A 2log10 reduction in E. faecalis CFU was observed immediately and after nine months in water storage. The formulation of MTZLNCs allowed the development of antibacterial calcium silicate-based-cements with suitable physicochemical properties and bioactivity, with a reduction in mechanical strength. The 0.3mg/ml concentration in cements liquid promoted effective and sustainable antibacterial activity.

Karaya/Gellan-Gum-Based Bilayer Films Containing 3,3'-Diindolylmethane-Loaded Nanocapsules: A Promising Alternative to Melanoma Topical Treatment.

This study aimed to incorporate nanocapsules containing 3,3'-diindolylmethane (DIM) with antitumor activity into a bilayer film of karaya and gellan gums for use in topical melanoma therapy. Nanocarriers and films were prepared by interfacial deposition of the preformed polymer and solvent casting methods, respectively. Incorporating DIM into nanocapsules increased its antitumor potential against human melanoma cells (A-375) (IC50 > 24.00 µg/mL free DIM × 2.89 µg/mL nanocapsules). The films were transparent, hydrophilic (θ < 90°), had homogeneous thickness and weight, and had a DIM content of 106 µg/cm2. Radical ABTS+ scavenger assay showed that the DIM films presented promising antioxidant action. Remarkably, the films showed selective bioadhesive potential on the karaya gum side. Considering the mechanical analyses, the nanotechnology-based films presented appropriate behavior for cutaneous application and controlled DIM release profile, which could increase the residence time on the application site. Furthermore, the nanofilms were found to increase the permeation of DIM into the epidermis, where melanoma develops. Lastly, the films were non-hemolytic (hemolysis test) and non-irritant (HET-CAM assay). In summary, the combination of karaya and gellan gum in bilayer films that contain nanoencapsulated DIM has demonstrated potential in the topical treatment of melanoma and could serve as a viable option for administering DIM for cutaneous melanoma therapy.

Influence of the Polymer and Solvent Variables on the Nanoencapsulation of the Flavonoid Quercetin: Preliminary Study Based on Eudragit® Polymers

Eudragit® polymers have proven their potential as a means to control the release of aqueous insoluble drugs in various delivery systems as polymer nanoparticles (PNPs). The size (S) and polydispersity index (PDI) of PNPs are crucial factors for their interaction with biological systems from a pharmaceutical standpoint. This study aimed to determine the impact of the volumes of the organic phase (OP) and aqueous phase (AP), as well as the polymer amount (PA), on the size and PDI of PNPs prepared using the nanoprecipitation method for encapsulating quercetin (Qr). The study also evaluated the toxic effects of PNPs on human erythrocytes. The PNPs were prepared using preformed polymers derived from methacrylic acid and polyvinyl alcohol (PVA) as a surfactant. The nanoprecipitation technique enabled the production of particles smaller than 200 nm with a PDI lower than 0.2, and the study established the significant impact (p &lt; 0.05) of the three variables related to the polymers and solvents. The selected PNPs contained 5 mg of Qr and 50 mg of Eudragit polymers (1:10 w/w Eudragit® EPO, E100, L100, and Eudragit L100-55) and diverse concentrations of PVA. The study found that including PVA in the AP increased the Qr encapsulation by up to 98%. The hemolytic potential of Eudragit® PNPs and Qr was assessed in human erythrocytes, with no significant cytotoxic activity observed (p &lt; 0.001) compared with the control. In conclusion, via the nanoprecipitation technique, preparing PNPs with defined and homogeneous S to entrap the flavonol Qr efficiently is possible.

Hydrogel Containing Silibinin-Loaded Pomegranate Oil-Based Nanocapsules for Cutaneous Application: In Vitro Safety Investigation and Human Skin Biometry and Permeation Studies.

In previous studies, we developed a hydrogel formulation containing silibinin-loaded pomegranate oil nanocapsules (HG-NCSB) that had improved in vivo anti-inflammatory action in comparison to non-encapsulated silibinin. To determine skin safety and whether the nanoencapsulation influences silibinin skin permeation, NCSB skin cytotoxicity, HG-NCSB permeation in human skin, and a biometric study with healthy volunteers were conducted. The formulation of nanocapsules was prepared by the preformed polymer method while the HG-NCSB was obtained by thickening the suspension of nanocarriers with gellan gum. The cytotoxicity and phototoxicity of nanocapsules were assessed in Keratinocytes (HaCaT) and fibroblast (HFF-1) using the MTT assay. The hydrogels were characterized regarding the rheological, occlusive, and bioadhesive properties, and silibinin permeation profile in human skin. The clinical safety of HG-NCSB was determined by cutaneous biometry in healthy human volunteers. NCSB yielded better cytotoxicity results than the blank nanocapsules (NCPO). NCSB did not cause photocytotoxicity, while NCPO and the non-encapsulated substances (SB and pomegranate oil) were phototoxic. The semisolids presented non-Newtonian pseudoplastic flow, adequate bioadhesiveness, and low occlusive potential. The skin permeation demonstrated that HG-NCSB retained a higher SB amount in the outermost layers than HG-SB. In addition, HG-SB reached the receptor medium and had a superior concentration of SB in the dermis layer. In the biometry assay, there was no significant cutaneous alteration after the administration of any of the HGs. Nanoencapsulation promoted greater SB retention in the skin, averted percutaneous absorption, and made the topical use of SB and pomegranate oil safer.

EXPERIENCE IN USING PRE-CROSSLINKED POLYMER SYSTEMS FOR ENHANCED OIL RECOVERY IN CARBONATE RESERVOIRS

Recovering residual oil reserves and reducing the level of water cut in produced wells at minimal cost are urgent tasks for mature fields. In such conditions, the use of tertiary methods of reservoir stimulation is relevant, among which a significant share is occupied by chemical methods of enhanced oil recovery. The principle of using flow diverting technologies is to supply small rims of chemical reagents to the reservoir through the reservoir pressure maintenance system, aimed at reducing the permeability of water-flushed zones by installing a waterinsulating barrier in them and redirecting water filtration flows to reservoir zones that were not previously covered by flooding.&#x0D; In this paper, we consider the possibility of using the technology of water-swellable preformed particle polymer systems as flow-diverting reagents to increase oil recovery from reservoirs with complicated geological and physical conditions that limit the use of many reagents used in EOR.&#x0D; On the example of a reagent sample, which is a pre-crosslinked acrylamide polymer, which contains particles of clay powder (up to 40% wt.), The paper shows the results of laboratory study and experience in applying the technology based on the preformed particle polymer systems at one of the objects of the Ural-Volga region, the reservoirs of which are presented carbonate rocks. The filtration experiment showed that the injection of the preformed particle polymer systems leads to a significant redistribution of fluid flows from a more highly permeable model to a less permeable one. As a result of the research, the main features of the applicability of technology based on the preformed particle polymer systems have been identified. The analysis of the conducted field work was carried out by determining the change in the injectivity profile of the treated injection wells and estimating the additionally produced oil from the reacting production wells. Based on the results of the analysis, additional laboratory studies were carried out, on the basis of which ways were proposed to increase the efficiency of injection well treatments with preformed particle polymer systems.

Cationic nanocapsule suspension as an alternative to the sublingual delivery of nifedipine

Nifedipine (NIFE) is a calcium channel blocker drug used to treat cardiovascular diseases, angina, and hypertension. However, NIFE is photolabile, has a short biological half-life, low aqueous solubility, and undergoes an intense first-pass effect, compromising its oral bioavailability. Thus, this study aimed to develop NIFE-loaded nanocapsules for sublingual administration. Nanocapsule suspensions of Eudragit® RS100 and medium chain triglycerides containing NIFE were prepared by the interfacial deposition of preformed polymer technique. The developed formulations showed particle size around 170 nm, polydispersity index below 0.2, positive zeta potential, and acid pH. The NIFE content was 0.98 ± 0.03 mg/mL, and the encapsulation efficiency was 99.9%. The natural light photodegradation experiment showed that the nanocapsules were able to provide NIFE photoprotection. The nanocapsules reduced the cytotoxicity of NIFE and showed no genotoxic effects in the Allium cepa model. Through the HET-CAM test, the formulations were classified as non-irritating. The developed nanocapsule suspension demonstrated a controlled release of NIFE and mucoadhesive potential. The in vitro permeation assay showed that the nanocapsules favored the NIFE permeation to the receptor compartment. In addition, the nanocapsules provided greater drug retention in the mucosa. Thus, the development of polymeric nanocapsule suspensions showed that this system could be a promising platform for NIFE sublingual administration.

Bioinspired crowding directs supramolecular polymerisation

Crowding effects are crucial to maintaining functionality in biological systems, but little is known about their role in analogous artificial counterparts. Within the growing field of supramolecular polymer science, crowding effects have hitherto remained underappreciated. Herein, we show that crowding effects exhibit strong and distinct control over the kinetics, accessible pathways and final outcomes of supramolecular polymerisation processes. In the presence of a pre-formed supramolecular polymer as crowding agent, a model supramolecular polymer dramatically changes its self-assembly behaviour and undergoes a morphological transformation from bundled fibres into flower-like hierarchical assemblies, despite no co-assembly taking place. Notably, this new pathway can only be accessed in crowded environments and when the crowding agent exhibits a one-dimensional morphology. These results allow accessing diverse morphologies and properties in supramolecular polymers and pave the way towards a better understanding of high-precision self-assembly in nature.

A review on the functions, preparation and future aspects of nanocapsules

The nano technology in medicinal field offers many exciting possibilities. Many techniques are being usedtoday. The application of many nanoparticles were developing and these involve the utilization of manufactured nanocapsules to form repairs at cellular level and it’s sometimes refers as nano medicine. Nanocapsules are submicroscopic colloidal drug carrier systems composed of an oily or an aqueous core surrounded by a thin polymer membrane. Two technologies can be used to obtain such nanocapsules: the interfacial polymerization of a monomer or the interfacial nanodeposition of a preformed polymer. In future the nanotechnology can creat many wonders in medical field. Nanotechnology is wonderfull technology that can used in diagnosis and treatment in medical field. This review was aimed to knowing the preparation, new aspects, and the applications of the nanocapsules.

Visualized Study on a New Preformed Particle Gels (PPG) + Polymer System to Enhance Oil Recovery by Oil Saturation Monitoring Online Flooding Experiment

After tertiary recovery from the oilfields, improving the production of the remaining hydrocarbon is always challenging. To significantly improve oil recovery, a heterogeneous composite flooding system has been developed with preformed particle gels (PPG) and polymers according to the technical approach of plugging and flooding combination. In addition, an oil saturation monitoring device and a large-scale 3D physical model were designed to better evaluate the performance of the technique. The evaluation results show that the viscosity, stability, and elasticity of the heterogeneous composite flooding system are better than the single polymer system. In addition, both systems exhibit pseudoplastic fluid characteristics and follow the principle of shear thinning. The results of seepage experiments showed that PPG migrates alternately in porous media in the manner of "piling plugging-pressure increasing-deformation migration". The heterogeneous composite system can migrate to the depths of the oil layer, which improves the injection profile. In the visualization experiment, the heterogeneous composite system preferentially flowed into the high-permeability layer, which increased the seepage resistance and forced the subsequent fluid to flow into the medium and low permeability layers. The average saturation of the high, medium, and low permeability layers decreased by 4.74%, 9.51%, and 17.12%, respectively, and the recovery factor was further improved by 13.56% after the polymer flooding.

Nanoencapsulation of Vaccinium ashei Leaf Extract in Eudragit® RS100-Based Nanoparticles Increases Its In Vitro Antioxidant and In Vivo Antidepressant-like Actions.

Depression is a major psychiatric disorder in Brazil and worldwide. Vaccinium ashei (V. ashei) leaves are cultivation by-products with high bioactive compound levels. Here, a hydroalcoholic extract of V. ashei leaves (HEV) was associated with Eudragit® RS100-based nanoparticles (NPHEV) to evaluate the in vitro antioxidant and in vivo antidepressant-like effects. Interfacial deposition of the preformed polymer method was used for NPHEV production. The formulations were evaluated regarding physicochemical characteristics, antioxidant activity (DPPH radical scavenging and oxygen radical absorbance capacity), and antidepressant-like action (1-25 mg/kg, single intragastric administration) assessed in forced swimming and tail suspension tests in male Balb-C mice. The NPHEV presented sizes in the nanometric range (144-206 nm), positive zeta potential values (8-15 mV), polydispersity index below 0.2, and pH in the acid range. The phenolic compound content was near the theoretical values, although the rutin presented higher encapsulation efficiency (~95%) than the chlorogenic acid (~60%). The nanoencapsulation improved the HEV antioxidant effect and antidepressant-like action by reducing the immobility time in both behavioral tests. Hence, Eudragit® RS100 nanoparticles containing HEV were successfully obtained and are a promising alternative to manage depression.

Covalent post-assembly modification of π-conjugated supramolecular polymers delivers structurally robust light-harvesting nanoscale objects.

A two-component stapling strategy is used to covalently tether a new class of water-soluble supramolecular polymers built from bay-functionalized perylene bisimide (PBI) units. By leveraging a novel combined strategy where excitonic coupling and fluorescence data are exploited as spectroscopic reporters, structural design principles are established to form light-harvesting superstructures whose ground-state electronic properties are not sensitive to solvation environments. Moreover, we interrogate the structural properties of stapled superstructures by capitalizing on the drastic changes in fluorescence quantum yields against parent supramolecular assemblies. In essence, our work shows that the combination of excitonic coupling measurements and photoluminescence experiments delineates a more accurate understanding of the design principles required to limit the degree of structural defects and magnify short- and long-range electronic couplings between redox-active units in this new class of solvated nanoscale objects. These results highlight that the fragile conformation of non-covalent assemblies, which are regulated by weak secondary interactions, can be preserved by post-assembly modification of preformed supramolecular polymers. These synthetic and spectroscopic principles can in turn be codified as experimental handles to parameterize the optoelectronic properties of light-harvesting nanoscale objects.

Swelling induced debonding of thin hydrogel films grafted on silicon substrates.

We report on the delamination of thin (≈μm) hydrogel films grafted to silicon substrates under the action of swelling stresses. Poly(dimetylacrylamide) (PDMA) films are synthesized by simultaneously cross-linking and grafting preformed polymer chains onto the silicon substrate using a thiol-ene reaction. The grafting density at the film/substrate interface is tuned by varying the surface density of reactive thiol-silane groups on the silicon substrate. Delamination of the films from well controlled line defects with low adhesion is monitored under a humid water vapor flow ensuring full saturation of the polymer network. A propagating delamination of the film is observed under the action of differential swelling stresses at the debonding front. A threshold thickness for the onset of this delamination is evidenced which is increasing with grafting density while the debonding velocity is also observed to decrease with an increase in grafting density. These observations are discussed within the framework of a nonlinear fracture mechanics model which assumes that the driving force for crack propagation is the difference between the swelling state of the bonded and delaminated parts of the film. Using this model, the threshold energy for crack initiation was determined from the measured threshold thickness and discussed in relation to the surface density of reactive thiol groups on the substrate.

Locust bean gum-based hydrogel containing nanocapsules for 3,3′-diindolylmethane delivery in skin inflammatory conditions

A hydrogel based on polymeric nanocapsules containing 3,3′-diindolmethane (DIM) was developed for the treatment of skin inflammatory disorders. Nanocapsule suspensions were prepared by interfacial deposition of preformed polymer method and thickened using locust bean gum (3%) to obtain hydrogels. The hydrogels showed satisfactory DIM content (1 mg/g), pH in the neutrality range (6.59–6.82), particle size in nanometric scale (around 140 nm) and non-Newtonian pseudoplastic behavior. In addition, nano-based formulations showed a greater amount of DIM released in vitro, and a smaller amount of active in the dermis was observed in the evaluation of skin permeation. The HET-CAM assay classified the hydrogels as non-irritating. Finally, the performance of hydrogels in two in vivo models of skin inflammation was evaluated. The evaluation of the anti-inflammatory effect in a model induced by croton oil showed that the nano-based hydrogels maintained the DIM activity, reducing ear edema and leukocyte infiltration. Regarding the UVB radiation-induced inflammation model, only nano-based hydrogels prolonged the in vivo anti-inflammatory effect of DIM up to 48 h, indicating a prolonged effect for nanocapsules. Therefore, the nano-based hydrogels demonstrate advantageous characteristics that may enhance the effects of DIM when applied to the skin, which may be of interest in the treatment of cutaneous inflammatory disorders.