Publications

Noninvasive cell-type-specific manipulation of neural signaling is critical in basic neuroscience research and in developing therapies for neurological disorders. Magnetic nanotechnologies have emerged as non-invasive neuromodulation approaches with high spatiotemporal control. We recently developed a wireless force-induced neurostimulation platform utilizing micro-sized magnetic discs (MDs) and low-intensity alternating magnetic fields (AMFs). When targeted to the cell membrane, MDs AMFs-triggered mechanoactuation enhances specific cell membrane receptors resulting in cell depolarization. Although promising, it is critical to understand the role of mechanical forces in magnetomechanical neuromodulation and their transduction to molecular signals for its optimization and future translation.

Gene editing has emerged as a therapeutic approach to manipulate the genome for killing cancer cells, protecting healthy tissues, and improving immune response to a tumor. The gene editing tool achaete-scute family bHLH transcription factor 1 CRISPR guide RNA (ASCL1-gRNA) is known to restore neuronal lineage potential, promote terminal differentiation, and attenuate tumorigenicity in glioblastoma tumors. Here, we fabricated a polymeric nonviral carrier to encapsulate ASCL1-gRNA by electrostatic interactions and deliver it into glioblastoma cells across a 3D in vitro model of the blood–brain barrier (BBB). To mimic rabies virus (RV) neurotropism, gene-loaded poly(β-amino ester) nanoparticles are surface functionalized with a peptide derivative of rabies virus glycoprotein (RVG29). The capability of the obtained NPs, hereinafter referred to as RV-like NPs, to travel across the BBB, internalize into glioblastoma cells, and deliver ASCL1-gRNA is investigated in a 3D BBB in vitro model through flow cytometry and CLSM microscopy. The formation of nicotinic acetylcholine receptors in the 3D BBB in vitro model is confirmed by immunochemistry. These receptors are known to bind to RVG29. Unlike Lipofectamine which primarily internalizes and transfects endothelial cells, RV-like NPs are capable to travel across the 3D BBB in vitro model, preferentially internalizing glioblastoma cells, and delivering ASCL1-gRNA at an efficiency of 10%, causing noncytotoxic effects.

The galvanotaxis response of Paramecium tetraurelia was explored as a preliminary model for in vitro electrostimulation of other eukaryotic cells. Interestingly, electrodes coated with 3,4-ethylenedioxythiophene (EDOT)–pyrrole (Py) copolymer induced galvanotaxis in a similar manner and with even greater efficiency than conventional electrodes. Furthermore, in the absence of agar bridges, there was no release of toxic species into the cell medium or any deleterious effects on cell viability after several cycles of electrostimulation for 1 min. The intrinsic cytotoxicity of the copolymer was also investigated in Paramecium tetraurelia and mammalian cell lines. The copolymer did not show any toxic effects at concentrations below 1 mg/ml. Finally, it was discovered that galvanotaxis can be increased by up to 150 % concerning the control (with electrostimulation of 3V for 60s) in Paramecium cells treated with 10 μg/mL copolymer particles for 1 h and that showed endocytosis. Galvanotaxis is voltage-dependent, as it only increases by 100 % at 1.5 V, suggesting a sensitive physiological level effect on the Ca2+ currents and voltage-dependent Ca2+ channels of the cilia.

Noninvasive manipulation of cell signaling is critical in basic neuroscience research and in developing therapies for neurological disorders and tissue engineering and regenerative medicine approaches. In this work, biomimetic synthesized conductive copolymer 3,4-ethylenedioxythiophene (EDOT)-Pyrrole nanoparticles (RB02 NPs) were used for wireless and localized stimulation of neurons. ¹H nuclear magnetic resonance was used to monitor the polymerization. RB02 NPs were characterized by Raman spectroscopy, Fourier transform infrared spectroscopy, and dynamic light scattering. The electrochemical properties were characterized by galvanostatic charge–discharge, voltammetry, and electrochemical impedance spectroscopy. For electrical stimulation of neurons, RB02 NPs were charged by applying 1 V to a NP suspension using platinum electrodes. The effect of NPs on ND7/23 neuron hybrid cell line viability was assessed by live/dead staining using flow cytometry. ND7/23 differentiation was evaluated by cell cytoskeleton staining and quantification of morphological parameters such as the dendrite number and length. Primary cortex neuron stimulation was studied by calcium ion influx detectable through the dynamic fluorescence changes of Fluo-4. RB02 NPs presented no toxicity toward ND7/23 cells. Furthermore, charged NPs enhanced cell differentiation at short times after addition (<6 h). Charged RB02 NPs largely increased the cortex neuronal activity. Altogether, biocompatible copolymer EDOT-Pyrrole nanoparticles present great potential for remote control of neural activities.

Minimally invasive manipulation of cell signaling is critical in basic neuroscience research and in developing therapies for neurological disorders. Here, a wireless chemomagnetic neuromodulation platform for the on-demand control of primary striatal neurons that relies on nanoscale heating events is described. Iron oxide magnetic nanoparticles (MNPs) are functionally coated with thermoresponsive poly (oligo (ethylene glycol) methyl ether methacrylate) (POEGMA) brushes loaded with dopamine. Dopamine loaded MNPs-POEGMA are co-cultured with primary striatal neurons. When alternating magnetic fields (AMF) are applied, MNPs undergo hysteresis power loss and dissipate heat. The local heat produced by MNPs initiates a thermodynamic phase transition on POEGMA brushes resulting in polymer collapse and dopamine release. AMF-triggered dopamine release enhances the response of dopamine ion channels expressed on the cell membranes enhancing the activity ≈50% of striatal neurons subjected to the treatment. Chemomagnetic actuation on dopamine receptors is confirmed by blocking D1 and D2 receptors. The reversible thermodynamic phase transition of POEGMA brushes allow the on-demand release of dopamine in multiple microdoses. AMF-triggered dopamine release from MNPs-POEGMA causes neither cell cytotoxicity nor promotes cell reactive oxygen species production. This research represents a fundamental step forward for the chemomagnetic control of neural activity using hybrid magnetic nanomaterials with tailored physical properties.

Photoresponsive soft materials are everywhere in the nature, from human’s retina tissues to plants, and have been the inspiration for engineers in the development of modern biomedical materials. Light as an external stimulus is particularly attractive because it is relatively cheap, noninvasive to superficial biological tissues, can be delivered contactless and offers high spatiotemporal control. In the biomedical field, soft materials that respond to long wavelength or that incorporate a photon upconversion mechanism are desired to overcome the limited UV–visible light penetration into biological tissues. Upon light exposure, photosensitive soft materials respond through mechanisms of isomerization, crosslinking or cleavage, hyperthermia, photoreactions, electrical current generation, among others. In this review, we discuss the most recent applications of photosensitive soft materials in the modulation of cellular behavior, for tissue engineering and regenerative medicine, in drug delivery and for phototherapies.

Noninvasive manipulation of cell signaling is critical in basic neuroscience research and in developing therapies for neurological disorders and psychiatric conditions. Here, the wireless force-induced stimulation of primary neuronal circuits through mechanotransduction mediated by magnetic microdiscs (MMDs) under applied low-intensity and low-frequency alternating magnetic fields (AMFs), is described. MMDs are fabricated by top-down lithography techniques that allow for cost-effective mass production of biocompatible MMDs with high saturation and zero magnetic magnetic moment at remanence. MMDs are utilized as transducers of AMFs into mechanical forces. When MMDs are exposed to primary rat neuronal circuits, their magneto-mechanical actuation triggers the response of specific mechanosensitive ion channels expressed on the cell membranes activating ≈50% of hippocampal and ≈90% of cortical neurons subjected to the treatment. Mechanotransduction is confirmed by the inhibition of mechanosensitive transmembrane channels with Gd³⁺. Mechanotransduction mediated by MMDs cause no cytotoxic effect to neuronal cultures. This technology fulfills the requirements of cell-type specificity and weak magnetic fields, two limiting factors in the development of noninvasive neuromodulation therapies and clinical equipment design. Moreover, high efficiency and long-lasting stimulations are successfully achieved. This research represents a fundamental step forward for magneto-mechanical control of neural activity using disc-shaped micromaterials with tailored magnetic properties.

The widespread occurrence of nosocomial infections and the emergence of new bacterial strands calls for the development of antibacterial coatings with localized antibacterial action that are capable of facing the challenges posed by increasing bacterial resistance to antibiotics. The Layer-by-Layer (LbL) technique, based on the alternating assembly of oppositely charged polyelectrolytes, can be applied for the non-covalent modification of multiple substrates, including medical implants. Polyelectrolyte multilayers fabricated by the LbL technique have been extensively researched for the development of antibacterial coatings as they can be loaded with antibiotics, antibacterial peptides, nanoparticles with bactericide action, in addition to being capable of restricting adhesion of bacteria to surfaces. In this review, the different approaches that apply LbL for antibacterial coatings, emphasizing those that can be applied for implant modification are presented.

The increasing demand for organ replacements in a growing world with an aging population as well as the loss of tissues and organs due to congenital defects, trauma and diseases has resulted in rapidly evolving new approaches for tissue engineering and regenerative medicine (TERM). The extracellular matrix (ECM) is a crucial component in tissues and organs that surrounds and acts as a physical environment for cells. Thus, ECM has become a model guide for the design and fabrication of scaffolds and biomaterials in TERM. However, the fabrication of a tissue/organ replacement or its regeneration is a very complex process and often requires the combination of several strategies such as the development of scaffolds with multiple functionalities and the simultaneous delivery of growth factors, biochemical signals, cells, genes, immunomodulatory agents, and external stimuli. Although the development of multifunctional scaffolds and biomaterials is one of the most studied approaches for TERM, all these strategies can be combined among them to develop novel synergistic approaches for tissue regeneration. In this review we discuss recent advances in which multifunctional scaffolds alone or combined with other strategies have been employed for TERM purposes.