Self-fluorescent antibiotic MoOx–hydroxyapatite: a nano-theranostic platform for bone infection therapies

Nowadays, the repair of large-size bone defects represents a huge medical challenge. A line of attack is the construction of advanced biomaterials having multifunctional properties. In this work, we show the creation of biocompatible MoOx-hydroxyapatite nanoparticles (nano-HA/MoOx) that simultaneously exhibit self-activated fluorescence and antibiotic skills. Along this text, we demonstrate that the insertion of molybdenum, an essential trace element, into the non-stoichiometric calcium deficient hydroxyapatite lattice generates intrinsic electronic point defects that exacerbate its epifluorescence blue emission and provokes new red emissions, preserving, always, its bioactivity. Furthermore, these point defects, acting as electron acceptors, stimulate the materials´ biological redox status and promote the death of pathogen microorganisms after their direct contact. A putative mechanism, by which bacteria lose electrons from their metabolic circuit that alter the function of their cytoplasmic membrane and potentially die, agrees with our results. Our findings highlight the importance of tuning the electronic communications between biomaterial interfaces and biological units, and support the use of self-fluorescent MoOx-hydroxyapatite nanoparticles as fundamental building blocks for new real-time imaging platforms against bone infection.Fil: Placente, Damián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Ruso, Juan Manuel. Universidad de Santiago de Compostela; EspañaFil: Baldini, Monica Diana. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Laiuppa, Juan Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Ciencias Biológicas y Biomédicas del Sur. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Instituto de Ciencias Biológicas y Biomédicas del Sur; ArgentinaFil: Sieben, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería Química. Instituto de Electroquímica y Corrosión; ArgentinaFil: Santillán, Graciela Edith. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Ciencias Biológicas y Biomédicas del Sur. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia. Instituto de Ciencias Biológicas y Biomédicas del Sur; ArgentinaFil: Messina, Paula Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Multiscale inorganic hierarchically materials: towards an improved orthopaedic regenerative medicine

Bone is a biologically and structurally complex multifunctional tissue. It dynamically responds to biochemical, mechanical and electrical signals by remodelling itself so that maximum strength and toughness are along the lines of the greatest applied stress. The challenge is to develop an orthopaedic biomaterial that emulates the micro- and nano-structural elements and compositions of bone to locally match the properties of the host tissue resulting in a biologically fixed implant. Looking for the ideal implant, the convergence of life and materials sciences occurs. Researchers in many different fields apply their expertise to improve implantable devices and regenerative medicine. Materials of all kinds, but especially hierarchical nano-materials, are being exploited. The application of nano-materials with hierarchical design to calcified tissue reconstructive medicine involve intricate systems including scaffolds with multifaceted shapes that provides temporary mechanical function; materials with nano-topography modifications that guarantee their integration to tissues and that possesses functionalized surfaces to deliver biologic factors to stimulate tissue growth in a controlled, safe, and rapid manner. Also materials that should degrade on a timeline matched to the time it takes to grow tissues are prepared. These implantable device systems are multifunctional and require specific design techniques coupled with several material manufacturing processes that can be integrated to achieve the design that can address the required multifunctionality. For such reasons, even though the concept shift from synthetic implants and tissue grafts to regenerative-medicine-based tissue reconstruction has been assured for well over a decade, the reality has yet to emerge. In this paper, we review the recent approaches to create enhanced bioactive materials. Their design and manufacturing processes as well as the challenges to integrate them to engineer hierarchical inorganic materials for their practical application in calcified tissue reparation are evaluated.Fil: Ruso, Juan Manuel. Universidad de Santiago de Compostela; EspañaFil: Sartuqui, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Messina, Paula Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; Argentin

Quantitative analysis of complex nanocomposites based on straight skeletonization

Bones are complex nanocomposites composed mainly by hydroxyapatite nanocrystals. Different factors characterize its morphology: composition, length, orientation, roughness. To increase our understanding of the tissue morphology at this fundamental lever of organization, a new method based on the straight skelonization of the images obtained by electronic microscopy is proposed. The method detects and measures the length and angularity of any straight edge of over the image. The technique resolved several test patterns independent of size and angle of rotation. Several samples obtained from different substrates were analyzed with the method. The results were consistent with those values obtained from conventional methods. Although still limited as a laboratory application, shape analysis has the potential to provide insight into the mechanisms of crystal growing and may provide a basis for specifications or guidelines for the manufacturing of biomaterial for bone tissue engineering. Our proposed automated computational method for the analysis and quantification digital images of bone tissue at microscale provide a rapid and accurate of the mechanical properties of the tissue.Fil: Tahoces, Pablo G.. Universidad de Santiago de Compostela; EspañaFil: Messina, Paula Verónica. Universidad Nacional del Sur; ArgentinaFil: Ruso, Juan Manuel. Universidad de Santiago de Compostela; Españ

Soft Actuated Hybrid Hydrogel with Bioinspired Complexity to Control Mechanical Flexure Behavior for Tissue Engineering

Hydrogels exhibit excellent properties that enable them as nanostructured scaffolds for soft tissue engineering. However, single-component hydrogels have significant limitations due to the low versatility of the single component. To achieve this goal, we have designed and characterized different multi-component hydrogels composed of gelatin, alginate, hydroxyapatite, and a protein (BSA and fibrinogen). First, we describe the surface morphology of the samples and the main characteristics of the physiological interplay by using fourier transform infrared (FT-IR), and confocal Raman microscopy. Then, their degradation and swelling were studied and mechanical properties were determined by rheology measurements. Experimental data were carefully collected and quantitatively analyzed by developing specific approaches and different theoretical models to determining the most important parameters. Finally, we determine how the nanoscale of the system influences its macroscopic properties and characterize the extent to which degree each component maintains its own functionality, demonstrating that with the optimal components, in the right proportion, multifunctional hydrogels can be developedThe authors acknowledge Ministerio de Ciencia e Innovación (PID2019-111327GB-100) and Xunta de Galicia (ED41E2018/08)S

The design and green nanofabrication of noble hydrogel systems with encapsulation of doped bioactive hydroxyapatite toward sustained drug delivery

Finding a bioactive hybrid material with the potential for a controlled drug release has been one of the major targets of tissue engineering in the recent years. In this line, the present work describes a new approach for producing singular hydrogel microparticles (HMPs) with different morphologies and compositions by combining experimental and computational methods. Calcium-Alginate microparticles (Ca-ALG) and core–shell Alginate-Chitosan microspheres (Ca-ALG-CHI) were synthesized with the presence of drug-doped Hydroxyapatite (HA) in their inner matrix. The methodology relies on the use of a microfluidic system to obtain crosslinked HMPs with homogeneous sizes and morphologies, integrating external and internal gelation. The impact of the water-to-oil volume ratio, as well as variations in the collecting baths, morphology, and dispersion, were considered. The drug models chosen were Propranolol hydrochloride and Cloxacillin sodium salt monohydrate. Avrami's parameters were used to study and address the adsorption kinetics of each drug onto the bioactive HA, and the Korsmeyer-Peppas model was used to analyze the posterior desorption profiles. The conception and development of this type of hydrogel microparticles with improved functionalities are essential for the creation of granular hydrogels, which are an innovative, green, sustained and highly promising solution for different therapies in regenerative medicine areasThe authors acknowledge Ministerio de Ciencia e Innovacion (PID2019-111327GB-100). N. H. thanks Proyecto FONDECYT de Iniciación (11170849) and FONDAP (15130011)S

Lysozyme allosteric interactions with β-blocker drugs

Effective and reliable prediction of allosteric molecular interactions involved in protein-ligand systems are essential to understand pharmacological modulation and toxicology processes that are driven by multiple factors covering from the atomistic to cellular level. Even though the interactions taking place within a defined biophysical environment are usually intricate and complex, having a preliminary knowledge of the structural determinant and biochemical function of target enzyme in the physiological or unbound state represent a step forward in the characterization of the forces involved these processes under interaction conditions as induced by drugs. In the present work, we tackle the study of relevant binding interactions between two well-recognized betablocker drugs and the lysozyme biological target from an experimental-computational perspective. In this way, molecular docking, machine learning and perturbation analysis combined with UV–vis and fluorescence measurements will allow us to determine the allosteric regulation and functional dynamics of lysozyme by binding propranolol and acebutololThe authors acknowledge Ministerio de Ciencia e Innovación (PID2019-111327GB-100)S

Conformational binding mechanism of lysozyme induced by interactions with penicillin antibiotic drugs

In this study we present an in-depth and detailed analysis of the binding process between two antibiotics (cloxacillin and dicloxacillin) and a blood serum protein (lysozyme). Our objectives have been several: to determine, at the atomic level, the structural and conformational changes that take place in both molecular structures once the complex is formed; to investigate the effect that the substitution of a hydrogen atom for a chlorine atom has on the bonding process; and to relate these local modifications with macromolecular parameters. Achieving these goals requires a multi-pronged approach and effective resource management. In our case, we have combined different experimental (isothermal titration calorimetry, UV–vis and fluorescence spectroscopy) and computational techniques (molecular docking and network models), in order to obtain comprehensive and contrasted information of the interaction process. Both approaches have showed an excellent correlation, confirming that there is a single binding site, that both penicillins are moderate binders and hydrogen bond and van der Waals forces are predominant. On the other hand, the small discrepancies between the two techniques highlighted the pressing need to approach the study of these systems from both atomic and macromolecular perspectivesThe authors acknowledge Ministerio de Ciencia e Innovación (PID2019-111327GB-100)S

Advanced Materials Based on Nanosized Hydroxyapatite

The development of new materials based on hydroxyapatite has undergone a great evolution in recent decades due to technological advances and development of computational techniques. The focus of this review is the various attempts to improve new hydroxyapatite-based materials. First, we comment on the most used processing routes, highlighting their advantages and disadvantages. We will now focus on other routes, less common due to their specificity and/or recent development. We also include a block dedicated to the impact of computational techniques in the development of these new systems, including: QSAR, DFT, Finite Elements of Machine Learning. In the following part we focus on the most innovative applications of these materials, ranging from medicine to new disciplines such as catalysis, environment, filtration, or energy. The review concludes with an outlook for possible new research directionsThis research was funded by MINISTERIO DE CIENCIA E INNOVACIÓN (PID2019-111327GB-100).S

Towards improved magnetic fluid hyperthermia: major-loops to diminish variations in local heating

This is the accepted manuscript of the following citation: Munoz-Menendez, C., Serantes, D., Ruso, J., & Baldomir, D. (2017). Towards improved magnetic fluid hyperthermia: major-loops to diminish variations in local heating. Physical Chemistry Chemical Physics, 19(22), 14527-14532. doi: 10.1039/c7cp01442bIn the context of using magnetic nanoparticles for heat-mediated applications, the need of an accurate knowledge of the local (at the nanoparticle level) heat generation in addition to the usually studied global counterpart has been recently highlighted. Such a need requires accurate knowledge of the links among the intrinsic particle properties, system characteristics and experimental conditions. In this work we have investigated the role of the particles' anisotropy polydispersity in relation to the amplitude (Hmax) of the AC magnetic field using a Monte Carlo technique. Our results indicate that it is better to use particles with large anisotropy for enhancing global heating, whereas for achieving homogeneous local heating it is better to use lower anisotropy particles. The latter ensures that most of the system undergoes major-loop hysteresis conditions, which is the key-point. This is equivalent to say that low-anisotropy particles (i.e. with less heating capability) may be better for accurate heat-mediated applications, which goes against some research trends in the literature that seek for large anisotropy (and hence heating) valuesThe authors thank the Centro de Supercomputacio ´n de Galicia (CESGA) for the computational facilities. This work was co-financed by the Spanish MINECO (Project MAT2013-47078-C22-P), Xunta de Galicia, Spain (Project GRC 2014/013, ‘Programa de axudas a ´ etapa predoutoral’ and financial support of D.S. under Plan I2C) and ‘Fondo Social Europeo 2014/2020’S

New Mechanistic Insights on Carbon Nanotubes’ Nanotoxicity Using Isolated Submitochondrial Particles, Molecular Docking, and Nano-QSTR Approaches

Single-walled carbon nanotubes can induce mitochondrial F0F1-ATPase nanotoxicity through inhibition. To completely characterize the mechanistic effect triggering the toxicity, we have developed a new approach based on the combination of experimental and computational study, since the use of only one or few techniques may not fully describe the phenomena. To this end, the in vitro inhibition responses in submitochondrial particles (SMP) was combined with docking, elastic network models, fractal surface analysis, and Nano-QSTR models. In vitro studies suggest that inhibition responses in SMP of F0F1-ATPase enzyme were strongly dependent on the concentration assay (from 3 to 5 µg/mL) for both pristine and COOH single-walled carbon nanotubes types (SWCNT). Besides, both SWCNTs show an interaction inhibition pattern mimicking the oligomycin A (the specific mitochondria F0F1-ATPase inhibitor blocking the c-ring F0 subunit). Performed docking studies denote the best crystallography binding pose obtained for the docking complexes based on the free energy of binding (FEB) fit well with the in vitro evidence from the thermodynamics point of view, following an affinity order such as: FEB (oligomycin A/F0-ATPase complex) = −9.8 kcal/mol > FEB (SWCNT-COOH/F0-ATPase complex) = −6.8 kcal/mol ~ FEB (SWCNT-pristine complex) = −5.9 kcal/mol, with predominance of van der Waals hydrophobic nano-interactions with key F0-ATPase binding site residues (Phe 55 and Phe 64). Elastic network models and fractal surface analysis were performed to study conformational perturbations induced by SWCNT. Our results suggest that interaction may be triggering abnormal allosteric responses and signals propagation in the inter-residue network, which could affect the substrate recognition ligand geometrical specificity of the F0F1-ATPase enzyme in order (SWCNT-pristine > SWCNT-COOH). In addition, Nano-QSTR models have been developed to predict toxicity induced by both SWCNTs, using results of in vitro and docking studies. Results show that this method may be used for the fast prediction of the nanotoxicity induced by SWCNT, avoiding time- and money-consuming techniques. Overall, the obtained results may open new avenues toward to the better understanding and prediction of new nanotoxicity mechanisms, rational drug design-based nanotechnology, and potential biomedical application in precision nanomedicineThis research was funded by FCT/MCTES through national funds (Michael González-Durruthy, Riccardo Concu, and M. Natália D.S. Cordeiro), grant UID/QUI/50006/2020, as well as by Xunta de Galicia (Juan M. Ruso), grant ED41E2018/08S