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1.
Angew Chem Int Ed Engl ; 60(7): 3449-3453, 2021 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-33283392

RESUMO

The ring-opening polymerisation of α-amino acid N-carboxyanhydrides (NCAs) offers a simple and scalable route to polypeptides with predicted and narrow molecular weight distributions. Here we show how polyoxometalates (POMs)-redox-active molecular metal-oxide anions-can serve as inorganic scaffold initiators for such NCA polymerisations. This "On-POM polymerisation" strategy serves as an innovative platform to design hybrid materials with additive or synergistic properties stemming from the inorganic and polypeptide component parts. We have used this synthetic approach to synthesise a library of bactericidal poly(lysine)-POM hybrid derivatives that can be used to prevent biofilm formation. This versatile "On-POM polymerisation" method provides a flexible synthetic approach for combining inorganic scaffolds with amino acids, and the potential to tailor and improve the specificity and performance of hybrid antimicrobial materials.

2.
J Mater Chem B ; 12(12): 3144-3160, 2024 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-38456751

RESUMO

Biomimetic 3D models emerged some decades ago to address 2D cell culture limitations in the field of replicating biological phenomena, structures or functions found in nature. The fabrication of hydrogels for cancer disease research enables the study of cell processes including growth, proliferation and migration and their 3D design is based on the encapsulation of tumoral cells within a tunable matrix. In this work, a platform of gelatin methacrylamide (GelMA)-based photocrosslinked scaffolds with embedded colorectal (HCT-116) or pancreatic (MIA PaCa-2) cancer cells is presented. Prior to cell culture, the mechanical characterization of hydrogels was assessed in terms of stiffness and swelling behavior. Modifications of the UV curing time enabled a fine tuning of the mechanical properties, which at the same time, showed susceptibility to the chemical composition and crosslinking mechanism. All scaffolds displayed excellent cytocompatibility with both tumoral cells while eliciting various cell responses depending on the microenvironment features. Individual and collective cell migration were observed for HCT-116 and MIA PaCa-2 cell lines, highlighting the ability of the colorectal cancer cells to cluster into aggregates of different sizes governed by the surrounding matrix. Additionally, metabolic activity results pointed out to the development of a more proliferative phenotype within stiffer networks. These findings confirm the suitability of the presented platform of GelMA-based hydrogels to conduct 3D cell culture experiments and explore biological processes associated with colorectal and pancreatic cancer.


Assuntos
Neoplasias Colorretais , Gelatina , Humanos , Gelatina/química , Hidrogéis/química , Técnicas de Cultura de Células , Pâncreas , Técnicas de Cultura de Células em Três Dimensões , Microambiente Tumoral
3.
Macromol Biosci ; 23(12): e2300227, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37572331

RESUMO

From the first experiments with biomaterials to mimic tissue properties, the mechanical and biochemical characterization has evolved extensively. Several properties can be described, however, what should be essential is to conduct a proper and physiologically relevant characterization. Herein, the influence of the reaction media (RM) and swelling media (SM)-phosphate buffered saline (PBS) and Dulbecco's modified Eagle's medium (DMEM) with two different glucose concentrations-is described in gelatin methacrylamide (GelMA) hydrogel mechanics and in the biological behavior of two tumoral cell lines (Caco-2 and HCT-116). All scaffolds are UV-photocrosslinked under identical conditions and evaluated for mass swelling ratio and stiffness. The results indicate that stiffness is highly susceptible to the RM, but not to the SM. Additionally, PBS-prepared hydrogels exhibited a higher photopolymerization degree according to high resolution magic-angle spinning (HR-MAS) NMR. These findings correlate with the biological response of Caco-2 and HCT-116 cells seeded on the substrates, which demonstrated flatter morphologies on stiffer hydrogels. Overall, cell viability and proliferation are excellent for both cell lines, and Caco-2 cells displayed a characteristic apical-basal polarization based on F-actin/Nuclei fluorescence images. These characterization experiments highlight the importance of conducting mechanical testing of biomaterials in the same medium as cell culture.


Assuntos
Hidrogéis , Engenharia Tecidual , Humanos , Hidrogéis/farmacologia , Hidrogéis/química , Engenharia Tecidual/métodos , Gelatina/química , Células CACO-2 , Materiais Biocompatíveis/farmacologia , Materiais Biocompatíveis/química , Alicerces Teciduais/química
4.
ACS Appl Polym Mater ; 5(2): 1487-1498, 2023 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-36817339

RESUMO

The mechanical microenvironment plays a crucial role in the evolution of colorectal cancer, a complex disease characterized by heterogeneous tumors with varying elasticity. Toward setting up distinct scenarios, herein, we describe the preparation and characterization of gelatin methacrylamide (GelMA)-based hydrogels via two different mechanisms: free-radical photopolymerization and photo-induced thiol-ene reaction. A precise stiffness modulation of covalently crosslinked scaffolds was achieved through the application of well-defined irradiation times while keeping the intensity constant. Besides, the incorporation of thiol chemistry strongly increased stiffness with low to moderate curing times. This wide range of finely tuned mechanical properties successfully covered from healthy tissue to colorectal cancer stages. Hydrogels prepared in phosphate-buffered saline or Dulbecco's modified Eagle's medium resulted in different mechanical and swelling properties, although a similar trend was observed for both conditions: thiol-ene systems exhibited higher stiffness and, at the same time, higher swelling capacity than free-radical photopolymerized networks. In terms of biological behavior, three of the substrates showed good cell proliferation rates according to the formation of a confluent monolayer of Caco-2 cells after 14 days of cell culture. Likewise, a characteristic apical-basal polarization of cells was observed for these three hydrogels. These results demonstrate the versatility of the presented platform of biomimetic materials as in vitro cell culture scaffolds.

5.
Biomater Sci ; 11(6): 2103-2114, 2023 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-36723226

RESUMO

The combination drug regimens that have long been used to treat tuberculosis (TB), caused by Mycobacterium tuberculosis, are fraught with problems such as frequent administration, long duration of treatment, and harsh adverse effects, leading to the emergence of multidrug resistance. Moreover, there is no effective preventive vaccine against TB infection. In this context, nanoparticles (NPs) have emerged as a potential alternative method for drug delivery. Encapsulating antibiotics in biodegradable NPs has been shown to provide effective therapy and reduced toxicity against M. tuberculosis in different mammalian models, when compared to conventional free drug administration. Here, we evaluate the localization, therapeutic efficacy and toxic effects of polymeric micellar NPs encapsulating a promising but highly hydrophobic and toxic antitubercular drug bedaquiline (BQ) in zebrafish embryos infected with Mycobacterium marinum. Our study shows that the NP formulation of BQ improves survival and reduces bacterial burden in the infected embryos after treatment when compared to its free form. The intravenously injected BQ NPs have short circulation times due to their rapid and efficient uptake into the endothelial cells, as observed by correlative light and electron microscopy (CLEM).


Assuntos
Mycobacterium tuberculosis , Nanopartículas , Tuberculose , Animais , Peixe-Zebra , Micelas , Células Endoteliais , Antituberculosos/farmacologia , Antituberculosos/uso terapêutico , Antituberculosos/química , Tuberculose/tratamento farmacológico , Tuberculose/microbiologia , Nanopartículas/química , Mamíferos
6.
Org Biomol Chem ; 10(30): 5898-908, 2012 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-22592967

RESUMO

The synthesis and self-assembly properties of a fluorinated C(3)-symmetrical 3,3'-bis(acylamino)-2,2'-bipyridine discotic (1) in the mesophase and in solution are described. First, 3,4,5-tris-(1H,1H,2H,2H,3H,3H-perfluoroundecyl-1-oxy)benzoyl chloride was coupled to mono-t-BOC protected 2,2'-bipyridine-3,3'-diamine to afford after deprotection the corresponding fluorinated aromatic amine on a multigram scale. Then, three-fold reaction of this amine with trimesyl chloride yielded the target C(3)-symmetrical fluorinated disc. The latter displayed columnar liquid crystallinity over a temperature range of more than 350 K in which helical rectangular and hexagonal columnar mesophases were detected by X-ray diffraction measurements. (1)H-NMR spectroscopy showed a preorganized structure due to strong intramolecular hydrogen bonding between the amide N-H's and bipyridine nitrogen atoms, even in the presence of a large excess of hexafluoroisopropanol. This preorganized structure allows the formation of helical self-assemblies in fluorinated solvents, as was established using UV-Vis spectroscopy. The fluorinated disc and two chiral hydrocarbon analogues (a C(3)-symmetrical and a desymmetrized disc) were mixed in a 1:10 v:v mixture of methoxynonafluorobutane (MNFB) and 1,1,2-trichloro-1,2,2-trifluoroethane (Freon 113). Importantly, the C(3)-symmetrical hydrocarbon disc dissolves only in the presence of fluorinated disc in the latter solvent mixture, proving a mutual interaction. CD spectroscopy performed on these mixtures points to a preference for alternating self-assemblies of fluorinated and chiral hydrocarbon discotics.

7.
Chem Sci ; 14(1): 10-28, 2022 Dec 21.
Artigo em Inglês | MEDLINE | ID: mdl-36605748

RESUMO

Organo-functionalisation of polyoxometalates (POMs) represents an effective approach to obtain diverse arrays of functional structures and materials, where the introduction of organic moieties into the POM molecules can dramatically change their surface chemistry, charge, polarity, and redox properties. The synergistic combination of POMs and peptides, which perform a myriad of essential roles within cellular biochemistry, including protection and transport in living organisms, leads to functional hybrid materials with unique properties. In this Perspective article, we present the principal synthetic routes to prepare and characterise POM-peptide hybrids, together with a comprehensive description of how their properties - such as redox chemistry, stereochemistry and supramolecular self-assembly - give rise to materials with relevant catalytic, adhesive, and biomedical applications. By presenting the state-of-the-art of the POM-peptide field, we show specifically how emerging chemical approaches can be harnessed to develop tailored POM-peptide materials with synergistic properties for applications in a variety of disciplines.

8.
Nanoscale ; 14(16): 5999-6006, 2022 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-35348148

RESUMO

Developing artificial metalloenzymes that possess a superior performance to their natural counterparts is an attractive concept. Polyoxometalates (POMs) are a class of anionic molecular metal-oxides with excellent redox properties and bioactivity. We have recently introduced "POMlymers" - covalently conjugated POM-peptide hybrid materials - where the polypeptide chain is obtained through a ring-opening polymerisation (ROP) of α-amino acid N-carboxyanhydrides (NCA) on an inorganic POM scaffold. Attracted by the idea of preparing artificial metalloenzymes, here we report the supramolecular self-assembly of POMlymer hybrids into nanoparticles where an optimal environment for catalysis is created. Our results demonstrate that the self-assembly of covalent POMlymers, enhances the peroxidase-like activity of the parent POM anion whereas, in contrast, the catalytic activity for nanoparticles obtained by ionic self-assembly of the same peptide and POM components practically disappears. Furthermore, POMlymer nanoparticles also present antimicrobial and antibiofilm activity against the skin bacterium Staphylococcus epidermidis; whereas, ionic POM-peptide hybrids significantly increase biofilm production and endogenous production of reactive oxygen species. In summary, we present the self-assembly of POMlymer hybrids into nanoparticles and a combination of peroxidase activity and microbiology assays that show that the POM-peptide covalent bond is essential for the stability of the self-assembled nanoparticles and therefore for their catalytic and biological activity.


Assuntos
Metaloproteínas , Compostos de Tungstênio , Ânions , Biofilmes , Peptídeos/farmacologia , Peroxidase , Polieletrólitos , Compostos de Tungstênio/química
9.
ACS Appl Polym Mater ; 4(6): 4144-4153, 2022 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-35720671

RESUMO

The increasing resistance of pathogenic microorganisms against common treatments requires innovative concepts to prevent infection and avoid long-term microbe viability on commonly used surfaces. Here, we report the preparation of a hybrid antimicrobial material based on the combination of microbiocidal polyoxometalate-ionic liquids (POM-ILs) and a biocompatible polymeric support, which enables the development of surface coatings that prevent microbial adhesion. The composite material is based on an antibacterial and antifungal room-temperature POM-IL composed of guanidinium cations (N,N,N',N'-tetramethyl-N″, N″-dioctylguanidinum) combined with lacunary Keggin-type polyoxotungstate anions, [α-SiW11O39]8-. Integration of the antimicrobial POM-IL into the biocompatible, flexible, and stable polymer poly(methyl methacrylate) (PMMA) results in processable films, which are suitable as surface coatings or packaging materials to limit the proliferation and spread of pathogenic microorganisms (e.g., on public transport and hospital surfaces, or in ready-to-eat-food packaging).

10.
Chemistry ; 17(32): 8780-3, 2011 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-21735502

RESUMO

Lighten the load! A family of enantiopure 4-oxy-substituted 3-aminopyrrolidines arising from the enantioselective ring-opening of meso-3-pyrroline oxide have been developed as catalysts for the asymmetric, anti-selective Mannich reaction (see scheme; PMP=p-methoxyphenyl; PG=protecting group). Very high catalytic activity (down to 0.01 mol % loading) and stereoselectivity have been recorded.


Assuntos
Aldeídos/química , Iminas/química , Cetonas/química , Pirrolidinas/química , Aminas/síntese química , Aminas/química , Catálise , Cetonas/síntese química , Estrutura Molecular , Estereoisomerismo
11.
Beilstein J Org Chem ; 7: 1486-93, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-22238521

RESUMO

The application of polystyrene-immobilized proline-based catalysts in packed-bed reactors for the continuous-flow, direct, enantioselective α-aminoxylation of aldehydes is described. The system allows the easy preparation of a series of ß-aminoxy alcohols (after a reductive workup) with excellent optical purity and with an effective catalyst loading of ca. 2.5% (four-fold reduction compared to the batch process) working at residence times of ca. 5 min.

12.
ACS Appl Mater Interfaces ; 13(23): 27533-27547, 2021 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-34082528

RESUMO

Exposure of nanomaterials (NMs) to biological medium results in their direct interaction with biomolecules and the formation of a dynamic biomolecular layer known as the biomolecular corona. Despite numerous published data on nano-biointeractions, the role of protein glycosylation in the formation, characteristics, and fate of such nano-biocomplexes has been almost completely neglected, although most serum proteins are glycosylated. This study aimed to systematically investigate the differences in interaction of metallic NPs with glycosylated vs nonglycosylated transferrin. To reach this aim, we compared interaction mechanisms between differently sized, shaped, and surface-functionalized silver NMs and gold NMs to commercially available human transferrin (TRF), a glycosylated protein, and to its nonglycosylated recombinant form (ngTRF). Bovine serum albumin (BSA) was also included in the study for comparative purposes. Characterization of NMs was performed using transmission electron microscopy and dynamic and electrophoretic light scattering techniques. Fluorescence quenching and circular dichroism methods were used to evaluate protein binding constants on the nanosurface and conformational changes after the protein-NM interactions, respectively. Competitive binding of TRF, ngTRF, and BSA to the surface of different NMs was evaluated by separating them after extraction from protein corona by gel electrophoresis following quantification with a commercial protein assay. The results showed that the binding strength between NMs and transferrin and the changes in the secondary protein structure largely depend not only on NM physicochemical properties but also on the protein glycosylation status. Data gained by this study highlight the relevance of protein glycosylation for all future design, development, and efficacy and safety assessment of NMs.


Assuntos
Ouro/química , Nanopartículas Metálicas/química , Prata/química , Transferrina/metabolismo , Glicosilação , Humanos , Nanoestruturas , Ligação Proteica , Soroalbumina Bovina/química , Soroalbumina Bovina/metabolismo , Transferrina/química
13.
J Am Chem Soc ; 132(13): 4710-9, 2010 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-20039610

RESUMO

Several oligo(p-phenylene-vinylene) oligomers capped with a guanosine or a guanine moiety have been prepared via a palladium-catalyzed cross-coupling reaction. Their self-assembly, in both the absence and presence of alkaline salts, has been studied by means of different techniques in solution (NMR, MS, UV-vis, CD, fluorescence), solid state (X-ray diffraction), and on surfaces (STM, AFM). When no salt is added, these pi-conjugated molecules self-associate in a mixture of hydrogen-bonded oligomers, among which the G-quartet structure may be predominant if the steric hindrance around the guanine base becomes important. In contrast, in the presence of sodium or potassium salts, well-defined assemblies of eight functional molecules (8mers) can be formed selectively and quantitatively. In these assemblies, the pi-conjugated oligomers are maintained in a chirally tilted (J-type) stacking arrangement, which is manifested by negative Cotton effects, small bathochromic absorption and emission shifts, and fluorescence enhancements. Furthermore, these self-assembled organic nanostructures, approximately 1.5-2.0 nm high and 8.5 nm wide, exhibit an extraordinary stability to temperature or concentration changes in apolar media, and they can be transferred and imaged over solid substrates as individual nanoparticles, showing no significant dissociation or further aggregation.


Assuntos
Guanina/química , Guanosina/química , Nanopartículas/química , Polivinil/química , Polivinil/síntese química , Álcalis/química , Catálise , Ligação de Hidrogênio , Modelos Moleculares , Estrutura Molecular , Paládio/química , Tamanho da Partícula , Sais/química , Propriedades de Superfície
14.
Chemistry ; 16(7): 2258-71, 2010 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-20029922

RESUMO

Two novel nonsymmetrical disc-shaped molecules 1 and 2 based on 3,3'-bis(acylamino)-2,2'-bipyridine units were synthesized by means of a statistical approach. Discotic 1 possesses six chiral dihydrocitronellyl tails and one peripheral phenyl group, whereas discotic 2 possesses six linear dodecyloxy tails and one peripheral pyridyl group. Preorganization by strong intramolecular hydrogen bonding and subsequent aromatic interactions induce self-assembly of the discotics. Liquid crystallinity of 1 and 2 was determined with the aid of polarized optical microscopy, differential scanning calorimetry, and X-ray diffraction. Two columnar rectangular mesophases (Col(r)) have been identified, whereas for C(3)-symmetrical derivatives only one Col(r) mesophase has been found. In solution, the molecularly dissolved state in chloroform was studied with (1)H NMR spectroscopy, whereas the self-assembled state in apolar solution was examined with optical spectroscopy. Remarkably, these desymmetrized discotics, which lack one aliphatic wedge, behave similar to the symmetric parent compound. To prove that the stacking behavior of discotics 1 and 2 is similar to that of reported C(3)-symmetrical derivatives, a mixing experiment of chiral 1 with C(3)-symmetrical 13 has been undertaken; it has shown that they indeed belong to one type of self-assembly. This helical J-type self-assembly was further confirmed with UV/Vis and photoluminescence (PL) spectroscopy. Eventually, disc 2, functionalized with a hydrogen-bonding acceptor moiety, might perform secondary interactions with molecules such as acids.

15.
Chemistry ; 16(3): 810-21, 2010 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-20025000

RESUMO

N-Centred benzene-1,3,5-tricarboxamides (N-BTAs) composed of chiral and achiral alkyl substituents were synthesised and their solid-state behaviour and self-assembly in dilute alkane solutions were investigated. A combination of differential scanning calorimetry (DSC), polarisation optical microscopy (POM) and X-ray diffraction revealed that the chiral N-BTA derivatives with branched 3,7-dimethyloctanoyl chains were liquid crystalline and the mesophase was assigned as Col(ho). In contrast, N-BTA derivatives with linear tetradecanoyl or octanoyl chains lacked a mesophase and were obtained as crystalline compounds. Variable-temperature infrared spectroscopy showed the presence of threefold, intermolecular hydrogen bonding between neighbouring molecules in the mesophase of the chiral N-BTAs. In the crystalline state at room temperature a more complicated packing between the molecules was observed. Ultraviolet and circular dichroism spectroscopy on dilute solutions of N-BTAs revealed a cooperative self-assembly behaviour of the N-BTA molecules into supramolecular polymers with preferred helicity when chiral alkyl chains were present. Both the sergeants-and-soldiers as well as the majority-rules principles were operative in stacks of N-BTAs. In fact, the self-assembly of N-BTAs resembles closely that of their carbonyl (C=O)-centred counterparts, with the exception that aggregation is weaker and amplification of chirality is less pronounced. The differences in the self-assembly of N- and C=O-BTAs were analysed by density functional theory (DFT) calculations. These reveal a substantially lower interaction energy between the monomeric units in the supramolecular polymers of N-BTAs. The lower interaction energy is due to the higher energy penalty for rotation around the Ph--NH bond compared to the Ph--CO bond and the diminished magnitude of dipole-dipole interactions. Finally, we observed that mixed stacks are formed in dilute solution when mixing N-BTAs and C=O BTAs.

16.
Nanomaterials (Basel) ; 10(3)2020 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-32192152

RESUMO

Gold nanoprisms possess remarkable optical properties that make them useful for medical biotechnology applications such as diagnosis and photothermal therapy. However, shape-selective synthesis of gold nanoprisms is not trivial and typically requires either toxic surfactants or time-consuming purification protocols, which can limit their applicability. Here, we show how triangular gold nanoprisms of different sizes can be purified by precipitation using the non-toxic glutathione ligand, thereby removing the need for toxic surfactants and bottleneck purification techniques. The protocol is amenable for direct scaling up as no instrumentation is required in the critical purification step. The new purification method provides a two-fold increased yield in gold nanoprisms compared to electrophoretic filtration, while providing nanoprisms of similar localized surface plasmon resonance wavelength. Crucially, the gold nanoprisms isolated using this methodology show fewer non-specific interactions with cells and lower cellular internalization, which paves the way for a higher selectivity in therapeutic applications.

17.
Chemistry ; 15(9): 2071-80, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19142935

RESUMO

Molecular organization: Chiral benzene tricarboxamides with methyl substituents at defined positions self-assemble into supramolecular polymers of preferred helicity by three-fold alpha-helical-type hydrogen bonding. The odd-even effect is operative and all derivatives are liquid crystalline showing a Col(ho) phase (see figure).Asymmetric benzene-1,3,5-tricarboxamides (aBTAs) comprising two n-octyl and one chiral methyl-alkyl side chain were synthesised and characterised. The influence of the position and the configuration of the chiral methyl group (methyl at the alpha, beta or gamma position) in the aliphatic side chains on the liquid-crystalline properties and the aggregation behaviour of the aBTAs was systematically studied and compared to symmetrical benzene-1,3,5-tricarboxamides (sBTAs). Solid-state characterisation (polarised optical microscopy, IR spectroscopy, X-ray diffraction and differential scanning calorimetry) revealed that all aBTAs show threefold, alpha-helical-type intermolecular hydrogen bonding between neighbouring molecules and exhibit a columnar hexagonal organisation from room temperature to well above 200 degrees C. Moving the chiral methyl group closer to the amide group stabilises the liquid-crystalline state, as evidenced by a higher clearing temperature and corresponding enthalpy. The self-assembly of dilute solutions of the aBTAs in methylcyclohexane ( approximately 10(-5) mol L(-1)) was investigated with circular dichroism (CD) spectroscopy. The sign of the Cotton effect demonstrated a pronounced odd-even effect, whereas the value of the molar ellipticity, Deltaepsilon, in the aBTAs was independent of the position of the methyl group. Subsequent temperature-dependent CD measurements showed that the aggregation of all aBTAs can quantitatively be described by the nucleation-growth model and that the stability of the aggregates increases when the chiral methyl group is closer to the amide moiety. The results presented herein illustrate that even small changes in the molecular structure of substituted benzene-1,3,5-tri-carboxamides affect their solid-state properties and their self-assembly behaviour in dilute solutions.

18.
Langmuir ; 25(15): 8794-801, 2009 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-20050050

RESUMO

The importance of the role of alkane solvents in the self-assembly process of pi-conjugated molecules is well recognized but hardly understood. Here we present our results on the X-ray diffraction studies that we conducted to gain insight into the supramolecular structure of mixtures of a bipyridine-based molecule (1) with alkanes. Independent of the alkane used (linear or branched), above x(w) > 0.06 (with x(w) being the weight fraction of 1) the mixtures show lyotropic liquid-crystalline behavior. The nature of the lyomesophase depends only on x(w) and not on the nature of the alkane (linear or branched). A columnar rectangular phase is present when x(w) > 0.66. Upon dilution of 1, a columnar hexagonal phase is assigned first (0.50 < x(w) < 0.65), and finally a columnar nematic phase is observed when x(w) < 0.50. Concentration-dependent SAXD measurements revealed that the dilution of 1 can be viewed as a swelling process. First, solvent molecules occupy space between the columns formed by 1, which are not disrupted. This process can quantitatively be described by a 2D swelling model. Only at lower concentrations does 3D swelling start as the columns start breaking into shorter fragments.

19.
Macromol Biosci ; 19(4): e1800397, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30645022

RESUMO

The coating of polypeptidic micelles with sodium alginate is described as a strategy to improve the stability of micelles for drug delivery. Bedaquiline, approved in 2012 for the treatment of multidrug resistant tuberculosis, has been used as an example of hydrophobic drug to study the loading efficiency, the release of the encapsulated drug in different media, and the in vitro antimicrobial activity of the system. Alginate coating prevents the burst release of the drug from micelles upon dilution and leads to a sustained release in all tested media. In view of possible oral administration, the alginate coated micelles show better stability in gastric and intestinal simulated media. Notably, the encapsulated bedaquiline shows increased in vitro activity against Mycobacterium tuberculosis compared to free bedaquiline.


Assuntos
Alginatos , Diarilquinolinas , Micelas , Mycobacterium tuberculosis/crescimento & desenvolvimento , Alginatos/química , Alginatos/farmacologia , Cápsulas , Preparações de Ação Retardada/química , Preparações de Ação Retardada/farmacologia , Diarilquinolinas/química , Diarilquinolinas/farmacologia
20.
Curr Med Chem ; 25(35): 4602-4615, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29022501

RESUMO

BACKGROUND: Alzheimer's disease (AD) is a public health priority all over the world. The difficulty of fighting the disease consists mostly in the complexity of symptoms and causes, in the still poor knowledge of its mechanisms and in the existence of a latent, asymptomatic, preclinical stage. Although many drugs are continuously screened in clinical studies for the treatment of Alzheimer's disease, the unexpected lack of patient response and sometimes the important adverse effects make it a potential field of application for personalized medicine. OBJECTIVE: This perspective review proposes nanotechnology as a valuable tool for the application of personalized medicine to AD. METHODS: The aim of personalized medicine is the development of more patient-precise treatments based mostly on the knowledge of individual genetics as well as of disease progress, and of pharmacokinetics and metabolic response to available drugs. The optimization of new and more sensitive detection techniques is an important tool for obtaining the pool of data needed for prediction and understanding of patient response. RESULTS: Research in bionanosensors is already providing examples with high sensitivity for core and new biomarkers for AD. In therapy the functionalization of nanoparticle surface can add specificity for biological recognition or for improving the bioavailability. This would allow the administration of lower doses with less adverse effects due to the local targeting. CONCLUSION: Taking into account the promising characteristics of nanoparticles as excellent candidate tools for precision medicine development, the establishment of better standard methods for safety assessment and production scale up would be desirable for the nanomaterial fruitful employment.


Assuntos
Doença de Alzheimer/terapia , Nanotecnologia , Medicina de Precisão , Doença de Alzheimer/diagnóstico , Doença de Alzheimer/tratamento farmacológico , Peptídeos beta-Amiloides/química , Peptídeos beta-Amiloides/metabolismo , Barreira Hematoencefálica/metabolismo , Meios de Contraste/química , Humanos , Nanopartículas/química , Nanopartículas/metabolismo , Peptídeos/química , Peptídeos/uso terapêutico
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