Alternating magnetic field mediated release of fluorophores from magnetic nanoparticles by hysteretic heating

Near-Infrared Induced miR-34a Delivery from Nanoparticles in Esophageal Cancer Treatment

Current nucleic acid delivery methods have not achieved efficient, non-toxic delivery of miRNAs with tumor-specific selectivity. In this study, a new delivery system based on light-inducible gold-silver-gold, core-shell-shell (CSS) nanoparticles is presented. This system delivers small nucleic acid therapeutics with precise spatiotemporal control, demonstrating the potential for achieving tumor-specific selectivity and efficient delivery of miRNA mimics. The light-inducible particles leverage the photothermal heating of metal nanoparticles due to the local surface plasmonic resonance for controlled chemical cleavage and release of the miRNA mimic payload. The CSS morphology and composition result in a plasmonic resonance within the near-infrared (NIR) region of the light spectrum. Through this method, exogenous miR-34a-5p mimics are effectively delivered to human squamous cell carcinoma TE10 cells, leading to apoptosis induction without adverse effects on untransformed keratinocytes in vitro. The CSS nanoparticle delivery system is tested in vivo in Foxn1nu athymic nude mice with bilateral human esophageal TE10 cancer cells xenografts. These experiments reveal that this CSS nanoparticle conjugates, when systemically administered, followed by 850 nm light emitting diode irradiation at the tumor site, 6 h post-injection, produce a significant and sustained reduction in tumor volume, exceeding 87% in less than 72 h.

Controlled Degradation of Polycaprolactone Polymers through Ultrasound Stimulation

This study describes the development of an ultrasound-responsive polymer system that provides on-demand degradation when exposed to high-intensity focused ultrasound (HIFU). Diels-Alder cycloadducts were used to crosslink polycaprolactone (PCL) polymers and underwent a retro Diels-Alder reaction when stimulated with HIFU. Two Diels-Alder polymer compositions were explored to evaluate the link between reverse reaction energy barriers and polymer degradation rates. PCL crosslinked with isosorbide was also used as a non-Diels-Alder-based control polymer. An increase of HIFU exposure time and amplitude correlated with an increase of PCL degradation for Diels-Alder-based polymers. Ultrasound imaging during HIFU allowed for real-time visualization of the on-demand degradation through cavitation-based mechanisms. The temperature surrounding the sample was monitored with a thermocouple during HIFU stimulation; a minimal increase in temperature was observed. PCL polymers were characterized using Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), optical profilometry, and mechanical testing. PCL degradation byproducts were identified by mass spectrometry, and their cytocompatibility was evaluated in vitro. Overall, this study demonstrated that HIFU is an effective image-guided, external stimulus to control the degradation of Diels-Alder-based PCL polymers on-demand.

Delivery of Therapeutic miR-148b Mimic via Poly(β Amino Ester) Polyplexes for Post-transcriptional Gene Regulation and Apoptosis of A549 Cells

In this study, we utilized selectively modified, biodegradable polymer-based polyplexes to deliver custom, exogenous miR-148b mimics to induce apoptosis in human lung cancer (A549) cells. The gene regulatory effects of the payload miRNA mimics (miR-148b-3p) were first evaluated through bioinformatic analyses to uncover specific gene targets involved in critical carcinogenic pathways. Hyperbranched poly(β amino ester) polyplexes (hPBAE) loaded with custom miR-148b mimics were then developed for targeted therapy. When evaluated in vitro, these hPBAE-based polyplexes sustained high intracellular uptake, low cytotoxicity, and efficient escape from endosomes to deliver functionally intact miRNA mimics to the cytosol. High-resolution confocal microscopy revealed successful intracellular uptake, cell viability was assessed through qualitative fluorescence microscopy and fluorescence-based DNA quantification, and successful cytosolic delivery of intact miRNA mimics was evaluated using real-time polymerase chain reaction (RT-PCR) to demonstrate target gene knockdown. The hPBAE-miRNA mimic polyplexes were shown to induce apoptosis among A549 cells through direct modulation of intracellular protein expression, targeting multiple potential carcinogenic pathways at the gene level. These results indicated that spatially controlled miR-148b mimic delivery can promote efficient cancer cell death in vitro and may lead to an enhanced therapeutic design for in vivo application.

Ultrasound-Responsive Hydrogels for On-Demand Protein Release

The development of tunable, ultrasound-responsive hydrogels that can deliver protein payload on-demand when exposed to focused ultrasound is described in this study. Reversible Diels-Alder linkers, which undergo a retro reaction when stimulated with ultrasound, were used to cross-link chitosan hydrogels with entrapped FITC-BSA as a model protein therapeutic payload. Two Diels-Alder linkage compositions with large differences in the reverse reaction energy barriers were compared to explore the influence of linker composition on ultrasound response. Selected physicochemical properties of the hydrogel construct, its basic degradation kinetics, and its cytocompatibility were measured with respect to Diels-Alder linkage composition. Focused ultrasound initiated the retro Diels-Alder reaction, controlling the release of the entrapped payload while also allowing for real-time visualization of the ongoing process. Additionally, increasing the focused ultrasound amplitude and time correlated with an increased rate of protein release, indicating stimuli responsive control.

Reversible Diels-Alder Reactions with a Fluorescent Dye on the Surface of Magnetite Nanoparticles

Diels–Alder reactions on the surface of nanoparticles allow a thermoreversible functionalization of the nanosized building blocks. We report the synthesis of well-defined magnetite nanoparticles by thermal decomposition reaction and their functionalization with maleimide groups. Attachment of these dienophiles was realized by the synthesis of organophosphonate coupling agents and a partial ligand exchange of the original carboxylic acid groups. The functionalized iron oxide particles allow a covalent surface attachment of a furfuryl-functionalized rhodamine B dye by a Diels–Alder reaction at 60 °C. The resulting particles showed the typical fluorescence of rhodamine B. The dye can be cleaved off the particle surface by a retro-Diels–Alder reaction. The study showed that organic functions can be thermoreversibly attached onto inorganic nanoparticles.

Quadruple abnormal protein aggregates in brainstem pathology and exogenous metal-rich magnetic nanoparticles (and engineered Ti-rich nanorods). The substantia nigrae is a very early target in young urbanites and the gastrointestinal tract a key brainstem portal

Fine particulate air pollution (PM_2.5) exposures are linked with Alzheimer's and Parkinson's diseases (AD,PD). AD and PD neuropathological hallmarks are documented in children and young adults exposed lifelong to Metropolitan Mexico City air pollution; together with high frontal metal concentrations (especially iron)-rich nanoparticles (NP), matching air pollution combustion- and friction-derived particles. Here, we identify aberrant hyperphosphorylated tau, ɑ synuclein and TDP-43 in the brainstem of 186 Mexico City 27.29 ± 11.8y old residents. Critically, substantia nigrae (SN) pathology seen in mitochondria, endoplasmic reticulum and neuromelanin (NM) is co-associated with the abundant presence of exogenous, Fe-, Al- and Ti-rich NPs.The SN exhibits early and progressive neurovascular unit damage and mitochondria and NM are associated with metal-rich NPs including exogenous engineered Ti-rich nanorods, also identified in neuroenteric neurons. Such reactive, cytotoxic and magnetic NPs may act as catalysts for reactive oxygen species formation, altered cell signaling, and protein misfolding, aggregation and fibril formation. Hence, pervasive, airborne and environmental, metal-rich and magnetic nanoparticles may be a common denominator for quadruple misfolded protein neurodegenerative pathologies affecting urbanites from earliest childhood. The substantia nigrae is a very early target and the gastrointestinal tract (and the neuroenteric system) key brainstem portals. The ultimate neural damage and neuropathology (Alzheimer's, Parkinson's and TDP-43 pathology included) could depend on NP characteristics and the differential access and targets achieved via their portals of entry. Thus where you live, what air pollutants you are exposed to, what you are inhaling and swallowing from the air you breathe,what you eat, how you travel, and your occupational longlife history are key. Control of NP sources becomes critical.