RESUMEN
Fabrication of scaffolds via 3D printing is a promising approach for tissue engineering. In this study, we combined 3D printing with cryogenic crosslinking to create biocompatible gelatin/oxidized alginate (Gel/OxAlg) scaffolds with large pore sizes, beneficial for bone tissue regeneration. To enhance the osteogenic effects and mechanical properties of these scaffolds, we evaluated the impact of hydroxyapatite (HAp) on the rheological characteristics of the 2.86% (1:1) Gel/OxAlg ink. We investigated the morphological and mechanical properties of scaffolds with low, 5%, and high 10% HAp content, as well as the resulting bio- and osteogenic effects. Scanning electron microscopy revealed a reduction in pore sizes from 160 to 180 µm (HAp-free) and from 120 to 140 µm for both HAp-containing scaffolds. Increased stability and higher Young's moduli were measured for 5% and 10% HAp (18 and 21 kPa, respectively) compared to 11 kPa for HAp-free constructs. Biological assessments with mesenchymal stem cells indicated excellent cytocompatibility and osteogenic differentiation in all scaffolds, with high degree of mineralization in HAp-containing constructs. Scaffolds with 5% HAp exhibited improved mechanical characteristics and shape fidelity, demonstrated positive osteogenic impact, and enhanced bone tissue formation. Increasing the HAp content to 10% did not show any advantages in osteogenesis, offering a minor increase in mechanical strength at the cost of significantly compromised shape fidelity.
RESUMEN
We report the synthesis, structures, and magnetic and luminescence properties of a series of new mono- and dinuclear Er3+ complexes derived from sterically demanding aryloxide and fluorinated alkoxide ligands: [4-tBu-2,6-(Ph2CH)2C6H2O]3Er(THF) (1), [(C6F5)3CO]3Er(Me3SiOH) (2), [(C6F5)3CO]3Er[(Me3Si)2NH] (3), [(C6F5)3CO]3Er(C6H5CH3) (4), [(C6F5)3CO]3Er(o-Me2NC6H4CH3) (5) and {[Ph(CF3)2CO]2Er(µ2-OC(CF3)2Ph)}2 (6). In compounds 1, 2, and 4, the Er3+ ion is four-coordinated and adopts a distorted trigonal pyramidal geometry, while in 3, 5, and 6, the coordination geometry of Er3+ is impacted by the presence of several relatively short Erâ¯F distances, making them rather 6-coordinated. All compounds behave as field-induced Single Molecule Magnets (SMMs) and exhibit an Er3+ characteristic near infrared (NIR) emission associated with the 4I13/2 â 4I15/2 transition with a remarkably long lifetime going up to 73 µs, which makes them multifunctional luminescent SMMs. The deconvolution of the NIR emission spectra allowed us to provide a direct probe of the crystal field splitting in these compounds, which was correlated with magnetic data.
RESUMEN
Terminology is pivotal for facilitating clear communication and minimizing ambiguity, especially in specialized fields such as chemistry. In materials science, a subset of chemistry, the term "pore" is traditionally linked to the International Union of Pure and Applied Chemistry (IUPAC) nomenclature, which categorizes pores into "micro", "meso", and "macro" based on size. However, applying this terminology in closely-related areas, such as 3D bioprinting, often leads to confusion owing to the lack of consensus on specific definitions and classifications tailored to each field. This review article critically examines the current use of pore terminology in the context of 3D bioprinting, highlighting the need for reassessment to avoid potential misunderstandings. We propose an alternative classification that aligns more closely with the specific requirements of bioprinting, suggesting a tentative size-based division of interconnected pores into 'parvo'-(d < 25 µm), 'medio'-(25 < d < 100 µm), and 'magno'-(d > 100 µm) pores, relying on the current understanding of the pore size role in tissue formation. The introduction of field-specific terminology for pore sizes in 3D bioprinting is essential to enhance the clarity and precision of research communication. This represents a step toward a more cohesive and specialized lexicon that aligns with the unique aspects of bioprinting and tissue engineering.
RESUMEN
Bis(carbazolide) complexes M[3,6-tBu2 -1,8-(RC≡C)2 Carb]2 (THF)n (R=SiMe3 , n=0, M=Ca, Yb; R=Ph, n=1, M=Ca, Yb; n=0, M=Yb) were synthesized through transamination reaction of M[N(SiMe3 )2 ]2 (THF)2 with two molar equivalents of carbazoles. The complexes feature M(η2 -C≡C)4 structural motif composed of M(II) ions encapsulated by four acetylene fragments due to atypical for alkaline- and rare-earth metals η2 -interactions with triple C≡C bond. This interaction is evidenced experimentally by X-ray diffraction, Raman spectroscopy in the solid state and by NMR-spectroscopy in the solution. According to QTAIM analysis there are 4 bond critical points (3;-1) between the metal atom and each of the triple bonds, which are connected by a strongly curved, almost T-shaped bond pathway.
RESUMEN
Gelatin-based hydrogels have emerged as a popular scaffold material for tissue engineering applications. The introduction of variable crosslinking methods has shown promise for fabricating stable cell-laden scaffolds. In this work, we examine promising composite biopolymer-based inks for extrusion-based 3D bioprinting, using a dual crosslinking approach. A combination of carefully selected printable hydrogel ink compositions and the use of photoinduced covalent and ionic crosslinking mechanisms allows for the fabrication of scaffolds of high accuracy and low cytotoxicity, resulting in unimpeded cell proliferation, extracellular matrix deposition, and mineralization. Three selected bioink compositions were characterized and the respective cell-laden scaffolds were bioprinted. Temporal stability, morphology, swelling, and mechanical properties of the scaffolds were thoroughly studied and the biocompatibility of the constructs was assessed using rat mesenchymal stem cells while focusing on osteogenesis. Experimental results showed that the composition of 1% alginate, 4% gelatin, and 5% (w/v) gelatine methacrylate, was found to be optimal among the examined, with shape fidelity of 88%, large cell spreading area and cell viability at around 100% after 14 days. The large pore diameters that exceed 100 µm, and highly interconnected scaffold morphology, make these hydrogels extremely potent in bone tissue engineering and bone organoid fabrication.
RESUMEN
Information related to the diverse and dynamic metabolite composition of the small intestine is crucial for the diagnosis and treatment of various diseases. However, our current understanding of the physiochemical dynamics of metabolic processes within the small intestine is limited due to the lack of in situ access to the intestinal environment. Here, we report a demonstration of a battery-free ingestible biosensing system for monitoring metabolites in the small intestine. As a proof of concept, we monitor the intestinal glucose dynamics on a porcine model. Battery-free operation is achieved through a self-powered glucose biofuel cell/biosensor integrated into a circuit that performs energy harvesting, biosensing, and wireless telemetry via a power-to-frequency conversion scheme using magnetic human body communication. Such long-term biochemical analysis could potentially provide critical information regarding the complex and dynamic small intestine metabolic profiles.
Asunto(s)
Comunicación , Tracto Gastrointestinal , Humanos , Porcinos , Animales , Suministros de Energía Eléctrica , Glucosa , TelemetríaRESUMEN
A series of new half-sandwich bis(alkyl) rare-earth metal complexes coordinated by a sterically demanding 1,3,6,8-tetra-tert-butyl-carbazol-9-yl ligand [tBu4Carb]La(CH2C6H5)2(THF) (1-La), [tBu4Carb]Ln(o-NMe2C6H4CH2)2 (Ln = Sc (2-Sc), Y (2-Y), La (2-La), [tBu4Carb]Ln(CH2SiMe3)2(THF) (Ln = Sc (3-Sc), Y (3-Y)), were synthesized. 1-La, 2-La, and 2-Y were prepared by an alkane elimination protocol, while 2-Sc, 3-Sc, and 3-Y became accessible only when salt metathesis reactions of tBu4CarbK with R2Ln(THF)n+[BPh4]- were employed. X-ray analysis revealed that in all complexes the carbazolyl ligand exhibits π-coordination with metal ions. 2-Sc and 3-Sc when activated with [Ph3C][B(C6F5)4] demonstrate excellent activity in α-olefin (octene-1, nonene-1, decene-1 and 1,1-diphenyl-but-1-ene) polymerization. When H2 was used as a chain transfer agent (1 bar, rt) in the presence of 3-Sc/[Ph3C][B(C6F5)4] or 2-Y, 2-La olefin hydrogenation occurred with quantitative conversion.
RESUMEN
A series of NHC-stabilized amido compounds (NHC)nM[N(SiMe3)2]2 (M = Yb(II), Sm(II), Ca(II); n = 1, 2) showed remarkable catalytic efficiency in addition of PhPH2 and PH3 to alkenes under mild conditions and low catalyst loading. The effect of σ-donor capacity of NHCs on catalytic activity in hydrophosphination of styrene with PhPH2 and PH3 was revealed. For the series of three-coordinate complexes 1-4M, a tendency to increase the catalytic activity with growth of σ-donating strength of the carbene ligand was clearly demonstrated. The complex (NHC)2Sm[N(SiMe3)2]2 (NHC = 1,3-diisopropyl-2H-imidazole-2-ylidene) (5Sm) proved to be the most efficient catalyst, which enabled hardly realizable transformations such as PhPH2 addition across internal CâC bonds of norbornene and cis- and trans-stilbenes, providing the highest reaction rate for addition of PH3 to styrene. Excellent regio- and chemoselectivities of alkylation of PH3 with styrenes allow for a selective and good-yield synthesis of desired organophosphinesâeither primary, secondary, or tertiary. Stepwise alkylation of PH3 with various substituted styrenes can be efficiently applied as an approach to nonsymmetric secondary phosphines. The rate equation of the addition of styrene to PH3 promoted by 5Sm was found: rate = k[styrene]1[5Sm]1.
RESUMEN
A series of bis(alkyl) complexes {(tBu)C[N(2,6-Me2C6H3)]2}Ln(CH2SiMe3)2(THF)n (Ln = Y, n = 1 (1); Ln = Sc, n = 1 (2)), {2-[Ph2P(O)]C6H4NC(tBu)N(2,6-Me2C6H3)}Sc(CH2SiMe3)2 (3), {2-[Ph2P(NPh)]C6H4NC(tBu)N(2,6-Me2C6H3)}Sc(CH2SiMe3)2 (4) coordinated by bidentate (N,N) and tridentate (N,N,O; N,N,N) amidinate ligands are synthesized using an alkane elimination approach. Yttrium complex 1 demonstrated a half-life of â¼2.5 days at room temperature in benzene-D6 (C6D6) solution, whereas scandium complexes proved to be much more stable (25 d (2), 30 d (3) and 42 d (4)). Complexes 1-4 as a part of ternary catalytic systems 1-4/TB, HNB/AlR3 (AlR3 = AliBu3, AliBu2H; TB = [Ph3C][B(C6F5)4], HNB = [PhNHMe2][B(C6F5)4]) demonstrated high catalytic activity in isoprene polymerization and enable 80%-100% conversion of 1000 equivalents of monomer into polymer at 25 °C within 3-180 min. The isolated polyisoprenes feature predominantly cis-1,4-regularity (69.2%-87.3%) and polydispersities Mw/Mn = 2.26-8.92. Moreover, the binary (2/TB) and ternary (1-4/TB/10 AliBu3) systems initiate 1-heptene polymerization providing 40%-100% conversion of 500 equivalents of monomer in 24 h at 25 °C giving polymer samples with Mn = 1.55-190.2 × 103 and Mw/Mn = 1.55-3.87.
RESUMEN
The reactions of 2-imino-2,3-dihydrobenzoxazole LH with M[N(SiMe3)2]2(THF)2 (M = Yb and Ca) and Y(CH2SiMe3)3(THF)2 proceed with the opening of the dihydrobenzoxazole ring and the elimination of HN(SiMe3)2 or SiMe4. Besides, in the case of Yb[N(SiMe3)2]2(THF)2, an electron transfer from Yb(II) to L takes place and Yb(III) complex 1 is coordinated by a dianionic phenolate ligand containing a pendant radical-anionic diazabutadiene fragment form. When LH is reacted with Ca[N(SiMe3)2]2(THF)2, C-H bond activation of a methyl fragment by imino nitrogen occurs and affords a dimeric calcium complex 2. In 2, the phenolate ligand is dianionic due to the presence of the amido-imino fragment [R-NîC(CH3)-C(îCH2)-NR']- (R = 2,4-tBu2-C6H2O; R' = 2,6-iPr2C6H3). In situ generated ate-complex {Na(Et2O)n}{Ca[N(SiMe3)2]3} also enables C-H bond activation, however the dianionic phenolate ligand in the resulting complex 3 contains an amido-imino fragment [R-N-C(îCH2)-C(CH3)îNR']- featuring the sequence of N-C and NîC bonds opposite to that in 2. The reaction of Y(CH2SiMe3)3(THF)2 with LH affords mono(alkyl) yttrium complex 4. 4 contains a dianionic amido-imino phenolate ligand resulting from the migration of one alkyl group to the CîN bond [R-N-C(Me)(CH2SiMe3)-C(Me)îNR']. 4 undergoes slow intramolecular C-H bond activation of the residual CH3 group to afford a yttrium complex coordinated by a trianionic diamido-phenolate ligand [R-N-C(Me)(CH2SiMe3)-C(îCH2)NR'].
RESUMEN
We report the synthesis, structures, and magnetic investigations of two new octahedral dysprosium complexes, based on the original N-heterocyclic carbene (NHC) tridentate bis(phenoxide) ligand, of the respective formulas mer-[DyL(THF)2Cl] (1) and mer-[DyL(THF)3][BPh4] (2), where L = 1,3-bis(3,5-di-tert-butyl-2-oxidophenyl)-5,5-dimethyl-3,4,5,6-tetrahydropyrimidin-1-ium chloride and THF = tetrahydrofuran. The short Dy-O distances in the axial direction in association with the weak donor ability of the NHC moiety provide a suitable environment for slow relaxation of magnetization, overcoming the previous single-molecule magnets based on NHC ligands.
RESUMEN
The catalytic activity in amine-borane dehydrogenation is shown for the first time for Ln(II) species using complexes [{(p-tBu-C6H4)2CH}2M·L] (M = Yb, Sm, L = (DME)2, TMEDA). The protonation of M(II)-C bonds with HNR1R2BH3 affords amidoborane complexes [M(NR1R2BH3)2L], which under excess HNMe2BH3 transform to [NMe2BH2NMe2BH3]- derivatives, both serving as the dehydrocoupling intermediates.
RESUMEN
We report the synthesis and structures of three luminescent dysprosium(iii) complexes based on fluorinated alkoxide ligands of formulas [Dy(L1)2(THF)4][BPh4]·0.5THF (1), [Dy(L2)2(THF)5][BPh4]·2.5THF (2) and [Dy(L3)2(THF)5][BPh4]·2THF (3) (L1 = (CF3)3CO-, L2 = C6F5C6F4O-, L3 = C6F5C(CH3)O-). Despite the different dysprosium ion geometries (octahedral vs. distorted pentagonal bipyramidal), these systems exhibit a single-molecule magnet (SMM) behavior, but with distinct relaxation dynamics. Moreover, a typical dysprosium-based luminescence is observed for the three complexes, which make them bifunctional magneto-luminescent SMMs. Remarkably, complex 3 exhibits a high anisotropy barrier of 1469 cm-1 and a blocking temperature of 22 K, making it one of the most performant alkoxide-based SMMs with the highest blocking temperature for a luminescent SMM.
RESUMEN
One of the factors hindering the development of enzymatic biosensors and biofuel cells in real-life applications is the time-dependant degradation of the biocatalysts on electrode surfaces. In this work, we present a new practical approach for extending the operation lifetimes of bioelectrocatalytic assemblies based on bilirubin oxidase (BOD). As evident by both spectroscopic and electrochemical measurements, an adsorption of carbon-coated magnetic nanoparticles (ccMNPs) onto a BOD/carbon nanotubes-deposited surface yields a stable bioelectrocathode system for mediatorless oxygen reduction. As compared to electrodes, which were stored without a preliminary interaction with the ccMNPs, an 80% increase in the active enzymatic content and the electrocatalytic performance was evident for the modified assemblies over a course of one month. As the full removal of the protective particles before the measurement requires only a single step applying an external magnetic force, the method is shown to be simple, reproducible, and easy to implement. Combined with the high efficiency in preserving the enzymatic stability and bioelectrocatalytic currents, the findings suggest a promising methodology for enhancing the lifetimes of bioelectronic applications.
Asunto(s)
Electrodos , Enzimas Inmovilizadas/metabolismo , Nanopartículas de Magnetita , Oxidorreductasas actuantes sobre Donantes de Grupo CH-CH/metabolismo , Fuentes de Energía Bioeléctrica , Estabilidad de Enzimas , ProteolisisRESUMEN
First Ln(ii) ring-expanded NHC complexes (er-NHC)Ln[N(SiMe3)2]2 (Ln = Sm, Yb) are synthesized and proved to be highly efficient pre-catalysts for the intermolecular hydrophosphination of such indolent substrates as 1-alkenes, cyclohexene and norbornene.
RESUMEN
We report the synthesis, structure and magnetic properties investigations of a series of new dysprosium heteroleptic mono- and dinuclear complexes based on the association of chloride and different diazabutadiene (DAD2R = [2,6-iPr2C6H3N-CR[double bond, length as m-dash]CR-NC6H3iPr2-2,6]; R = H, Me) ligands showing different redox states. While using dianionic DAD2R ligands affords the formation of dichloro-bridged dinuclear complexes [Dy2(DAD2R)(µ-Cl)2(THF)2] (R = H (1), Me (2)), two different mononuclear complexes of general formula [DyCl2(DAD2R)(THF)2] (R = H (3), Me (4)) could be obtained with either a radical monoanionic and a monoanionic DAD2R state, respectively. Remarkably, all the complexes exhibit a slow relaxation of their magnetization where the relaxation dynamics depends on both the nuclearity of the system and the DAD2R redox state.
RESUMEN
We report here the synthesis, structure, magnetic and photoluminescent properties of three new bifunctional Schiff-base complexes [Dy(L1 )2 (py)2 ][B(Ph)4 ]â py (1), [Dy(L1 )2 Cl(DME)] â 0.5DME (2) and [Dy(L2 )2 Cl] â 2.5(C7 H8 ) (3) (HL1 =Phenol, 2,4-bis(1,1-dimethylethyl)-6-[[(2-methoxy-5-methylphenyl)imino]methyl]; HL2 =Phenol, 2,4-bis(1,1-dimethylethyl)-6-[[(2-methoxyphenyl)imino]methyl]). The coordination environment of the Dy3+ ion and the direction of the anisotropic axis may be controlled by the combination of the substituent groups of the Schiff bases, the nature of the counter-ions (Cl- vs. BPh4 - ) and the coordinative solvent molecules. A zero-field slow relaxation of the magnetization is evidenced for all complexes but strong differences in the relaxation dynamics are observed depending on the Dy3+ site geometry. In this sense, complex 1 exhibits an anisotropy barrier of 472â cm-1 , which may be favourably compared to other related examples due to the shortening of the Dy-O bond in the axial direction. Besides, the three complexes exhibit a ligand-based luminescence making them as bifunctional magneto-luminescent systems.
RESUMEN
We report the synthesis, photoluminescence and magnetic properties of two octahedral dysprosium complexes [DyR2(py)4][BPh4]·2py (1) and [DyR2(THF)4][BPh4] (2) (R = carbazolyl, py = pyridine, THF = tetrahydrofuran) exhibiting a quasi linear N-Dy-N angle in the axial direction, suitable for providing a coordination environment allowing the zero-field slow relaxation of magnetization.
RESUMEN
We report the investigation of synthesis, structure and magnetic properties of a series of homoleptic Ln(iii) complexes coordinated by radical-anionic iminopyridine ligands of general formula [Ln(IPy)3]·solv (IPy = iminopyridine; Ln = Tb, Dy, Er, Y, Gd). The dysprosium analogue exhibits a zero-field Single-Molecule Magnet (SMM) behavior.
RESUMEN
Through a careful chemical and bioelectronic design we have created a system that uses self-assembly of enzyme-nanoparticle hybrids to yield bioelectrocatalytic functionality and to enable the harnessing of electrical power from biomass. Here we show that mixed populations of hybrids acting as catalyst carriers for clean energy production can be efficiently stored, self-assembled on functionalized stationary surfaces, and magnetically re-collected to make the binding sites on the surfaces available again. The methodology is based on selective interactions occurring between chemically modified surfaces and ligand-functionalized hybrids. The design of a system with minimal cross-talk between the particles, outstanding selective binding of the hybrids at the electrode surfaces, and direct anodic and cathodic electron transfer pathways leads to mediator-less bioelectrocatalytic transformations which are implemented in the construction of a fast self-assembling, membrane-less fructose/O2 biofuel cell.