The In Vivo Biological Fate of Protein Corona: A Comparative PET Study of the Fate of Soft and Hard Protein Corona in Healthy Animal Models.

Radiolabeling and nuclear imaging techniques are used to investigate the biodistribution patterns of the soft and hard protein corona around poly (lactic-co-glycolic acid) nanoparticles (PLGA NPs) after administration to healthy mice. Soft and hard protein coronas of 131I-labeled BSA or 131I-labeled serum are formed on PLGA NPs functionalized with either polyehtylenimine (PEI) or bovine serum albumin (BSA). The exchangeability of hard and soft corona is assessed in vitro by gamma counting exposing PLGA NPs with corona to non-labeled BSA, serum, or simulated body fluid. PEI PLGA NPs form larger and more stable coronas than BSA PLGA NPs. Soft coronas are more exchangeable than hard ones. The in vivo fate of PEI PLGA NPs coated with preformed 18F-labeled BSA hard and soft coronas is assessed by positron emission tomography (PET) following intravenous administration. While the soft corona shows a biodistribution similar to free 18F BSA with high activity in blood and kidney, the hard corona follows patterns characteristic of nanoparticles, accumulating in the lungs, liver, and spleen. These results show that in vivo fates of soft and hard corona are different, and that soft corona is more easily exchanged with proteins from the body, while hard corona is largely retained on the nanoparticle surface.

Positron Emission Tomography Studies of the Biodistribution, Translocation, and Fate of Poly Allyl Amine-Based Carriers for Sirna Delivery by Systemic and Intratumoral Administration.

Polyamine-based vectors offer many advantages for gene therapy, but they are hampered by a limited knowledge on their biological fate and efficacy for nucleic acid delivery. The 18 F radiolabeled siRNA is complexed with poly(allyl amine) hydrochloride (PAH), PEGylated PAH (PAHPEG ), or oleic acid-modified PAH (PAHOleic ) to form polyplexes, and injected them intravenously into healthy rodents. The biodistribution patterns obtained by positron emission tomography (PET) imaging vary according to the polymer used for complexation. Free siRNA is quickly eliminated through the bladder. PAH and oleic acid modify PAH polyplexes accumulate in the lungs and liver. No elimination through the bladder is observed for PAH and PAHOleic within 2 h after administration. PAHPEG polyplexes accumulate in kidneys and are eliminated through the bladder. Polyplexes prepared with 18 F-labeled oleic acid-modified PAH and non-labeled siRNA show similar biodistribution to those prepared with labeled siRNA, but with more accumulation in the lungs due to the presence of non-complexed polymer. Intravenous administration of PAHOleic polyplexes in tumor models results in a limited availability of siRNA. When PAHOleic polyplexes are administered intratumorally in tumor bearing rodents, ≈40% of the radioactivity is retained in the tumor after 180 min while free siRNA is completely eliminated.

Electrochemical Exfoliation of Graphene Oxide: Unveiling Structural Properties and Electrochemical Performance.

An electrochemical exfoliation method for the production of graphene oxide and its characterization by electrochemical techniques are presented here. Graphite rods are used as working electrode in a three-electrode electrochemical cell, and electro-exfoliation is achieved by applying anodic polarization in a sulfuric acid solution. The electrochemical process involved two steps characterized by an intercalation at lower potential and an exfoliation at higher potential. The electrochemical behavior of the produced GO is studied through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). X ray Photoelectronic Spectroscopy (XPS), Raman spectroscopy, Transmission Electron Microscopy (TEM), and Atomic Force Microscopy (AFM) are employed to characterize the structural and chemical properties of the exfoliated GO. The results demonstrate that the electrochemical exfoliation method yields GO materials with varying degrees of oxidation, defect density, and crystallite size, depending on the applied potential and acid concentration. The graphene oxide samples exhibited distinct electrochemical properties, including charge transfer resistance, interfacial capacitance, and relaxation times for the charge transfer, as revealed by CV and EIS measurements with a specifically selected redox probe. The comprehensive characterization performed provides valuable insights into the structure-property relationships of the GO materials synthesized through electrochemical exfoliation of graphite.

Importance of the Structural and Physicochemical Properties of Silica Nanoshells in the Photothermal Effect of Silica-Coated Au Nanoparticles Suspensions.

In this work, monodisperse silica-coated gold nanoparticles (NPs) were synthesized and used for obtaining aqueous colloidal dispersions with an optimum relationship between colloidal stability and photothermal activity. The idea behind this design was to produce systems with the advantages of the presence of a silica shell (biocompatibility, potential for surface modification, and protecting effect) with a minimal loss of optical and thermal properties. With this aim, the photothermal properties of NPs with silica shells of different thicknesses were analyzed under conditions of high radiation extinction. By using amorphous, gel-like silica coatings, thicknesses higher than 40 nm could be obtained without an important loss of the light absorption capacity of the colloids and with a significant photothermal response even at low NP concentrations. The effects produced by changes in the solvent and in the NP concentration were also analyzed. The results show that the characteristics of the shell control both, the photothermal effect and the optical properties of the colloidal dispersions. As the presence of a silica shell strongly enhances the possibilities of adding cargo molecules or probes, these colloids can be considered of high interest for biomedical therapies, sensing applications, remote actuation, and other technological applications.

Complexation and organization of doxorubicin on polystyrene sulfonate chains: impacts on doxorubicin dimerization and quenching.

Anthracycline doxorubicin hydrochloride (DX) is a positively charged fluorescent drug, which in water self-associates into non-fluorescent antiparallel dimers upon increasing concentration and/or ionic strength. The positive charge of DX allows for complexation with negatively charged polymers and drug carriers. The fluorescence of DX following complexation with polyanion polystyrene sulfonate (PSS) is studied here. The fluorescence emission of DX decreases in the presence of PSS, being almost completely quenched when the ratio (R) of PSS monomers-to-DX molecules is larger than 10. Increasing R values over 30 results in a progressive recovery of fluorescence. The circular dichroism of PSS-DX complexes shows inverted characteristic bands of DX dimers suggesting the presence of parallel dimers at a concentration of DX below dimerization in water. Molecular dynamics studies corroborate a preferential orientation of DX into parallel dimers when interacting with PSS and show that DX molecules interact with a binding pocket of PSS monomers rather than with one single monomer. Increasing the ionic strength results in a recovery of fluorescence without an apparent release of DX from the PSS-DX complex as shown by DOSY NMR. PSS acts as a template for concentrating DX, triggering dimerisation and orienting DX molecules with their charged groups facing the negatively charged PSS monomers.

In Vivo Tracking of the Degradation of Mesoporous Silica through 89 Zr Radio-Labeled Core-Shell Nanoparticles.

While mesoporous silica nanoparticles (MSNs) are extensively studied as high-potential drug delivery platforms, the successful clinical translation of these nanocarriers strongly depends on their biodistribution, biodegradation, and elimination patterns in vivo. Here, a novel method is reported to follow the in vivo degradation of MSNs by tracking a radioactive label embedded in the silica structure. Core-shell silica nanoparticles (NPs) with a dense core and a mesoporous shell are labeled with low quantities of the positron emitter 89 Zr, either in the dense core or in the mesoporous shell. In vivo positron emission tomography imaging and ex vivo organ measurements reveal a remarkable difference in the 89 Zr biodistribution between the shell-labeled and the core-labeled NPs. Release of the radiotracer from shell-labeled NPs is used as a probe of the extent of silica dissolution, and a prompt release of the radioisotope is observed, with partial excretion already in the first 2 h post injection, and a slower accumulation in bones over time. On the other hand, when 89 Zr is embedded in the nanoparticle core, the biodistribution remains largely unchanged during the first 6 h. These findings indicate that MSNs have fast, hour-scale, degradation kinetics in vivo.

Dual Monitoring of Surface Reactions in Real Time by Combined Surface-Plasmon Resonance and Field-Effect Transistor Interrogation.

By combining surface plasmon resonance (SPR) and electrolyte gated field-effect transistor (EG-FET) methods in a single analytical device we introduce a novel tool for surface investigations, enabling simultaneous measurements of the surface mass and charge density changes in real time. This is realized using a gold sensor surface that simultaneously serves as a gate electrode of the EG-FET and as the SPR active interface. This novel platform has the potential to provide new insights into (bio)adsorption processes on planar solid surfaces by directly relating complementary measurement principles based on (i) detuning of SPR as a result of the modification of the interfacial refractive index profile by surface adsorption processes and (ii) change of output current as a result of the emanating effective gate voltage modulations. Furthermore, combination of the two complementary sensing concepts allows for the comparison and respective validation of both analytical techniques. A theoretical model is derived describing the mass uptake and evolution of surface charge density during polyelectrolyte multilayer formation. We demonstrate the potential of this combined platform through the observation of layer-by-layer assembly of PDADMAC and PSS. These simultaneous label-free and real-time measurements allow new insights into complex processes at the solid-liquid interface (like non-Fickian ion diffusion), which are beyond the scope of each individual tool.

Surfactants as mesogenic agents in layer-by-layer assembled polyelectrolyte/surfactant multilayers: nanoarchitectured "soft" thin films displaying a tailored mesostructure.

Interfacial supramolecular architectures displaying mesoscale organized components are of fundamental importance for developing materials with novel or optimized properties. Nevertheless, engineering the multilayer assembly of different building blocks onto a surface and exerting control over the internal mesostructure of the resulting film is still a challenging task in materials science. In the present work we demonstrate that the integration of surfactants (as mesogenic agents) into layer-by-layer (LbL) assembled polyelectrolyte multilayers offers a straightforward approach to control the internal film organization at the mesoscale level. The mesostructure of films constituted of hexadecyltrimethylammonium bromide, CTAB, and polyacrylic acid, PAA (of different molecular weights), was characterized as a function of the number of assembled layers. Structural characterization of the multilayered films by grazing-incidence small-angle X-ray scattering (GISAXS), showed the formation of mesostructured composite polyelectrolyte assemblies. Interestingly, the (PAA/CTA)n assemblies prepared with low PAA molecular weight presented different mesostructural regimes which were dependent on the number of assembled layers: a lamellar mesophase for the first bilayers, and a hexagonal circular mesophase for n ≥ 7. This interesting observation was explained in terms of the strong interaction between the substrate and the first layers leading to a particular mesophase. As the film increases its thickness, the prevalence of this strong interaction decreases and the supramolecular architecture exhibits a "bulk" mesophase. Finally, we demonstrated that the molecular weight of the polyelectrolyte has a considerable impact on the meso-organization for the (PAA/CTA)n assemblies. We consider that these studies open a path to new rational methodologies to construct "nanoarchitectured" polyelectrolyte multilayers.

Gramicidin ion channels in a lipid bilayer supported on polyelectrolyte multilayer films: an electrochemical impedance study.

Supported membranes on polymer cushions are of fundamental interest as models for cell membranes. The use of polyelectrolyte multilayers (PEMs) assembled by the layer by layer (LbL) technique as supports for a bilayer allows for easy integration of the lipid bilayer on surfaces and devices and for nanoscale tunable spacing of the lipid bilayer. Controlling ionic permeability in lipid bilayers supported on PEMs triggers potential applications in sensing and as models for transport phenomena in cell membranes. Lipid bilayers displaying gramicidin channels are fabricated on top of polyallylamine hydrochloride (PAH) and polystyrene sulfonate (PSS) multilayer films, by the assembly of vesicles of phosphatidylcholine and phosphatidylserine, 50 : 50 M/M, carrying gramicidin (GA). Quartz crystal microbalance with dissipation shows that the vesicles with GA fuse into a bilayer. Atomic force microscopy reveals that the presence of GA alters the bilayer topography resulting in depressions in the bilayer of around 70 nm in diameter. Electrochemical impedance spectroscopy (EIS) studies show that supported bilayers carrying GA have smaller resistances than the bilayers without GA. Lipid layers carrying GA display a higher conductance for K+ than for Na+ and are blocked in the presence of Ca2+.

High Resistivity Lipid Bilayers Assembled on Polyelectrolyte Multilayer Cushions: An Impedance Study.

Supported membranes on top of polymer cushions are interesting models of biomembranes as cell membranes are supported on a polymer network of proteins and sugars. In this work lipid vesicles formed by a mixture of 30% 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 70% 1,2-dioleoyl-sn-glycero-3-phospho-l-serine (DOPS) are assembled on top of a polyelectrolyte multilayer (PEM) cushion of poly(allylamine hydrochloride) (PAH) and poly(styrene sodium sulfonate) (PSS). The assembly results in the formation of a bilayer on top of the PEM as proven by means of the quartz crystal microbalance with dissipation technique (QCM-D) and by cryo-transmission electron microscopy (cryo-TEM). The electrical properties of the bilayer are studied by electrochemical impedance spectroscopy (EIS). The bilayer supported on the PEMs shows a high resistance, on the order of 10(7) Ω cm(2), which is indicative of a continuous, dense bilayer. Such resistance is comparable with the resistance of black lipid membranes. This is the first time that such values are obtained for lipid bilayers supported on PEMs. The assembly of polyelectrolytes on top of a lipid bilayer decreases the resistance of the bilayer up to 2 orders of magnitude. The assembly of the polyelectrolytes on the lipids induces defects or pores in the bilayer which in turn prompts a decrease in the measured resistance.

Force spectroscopy predicts thermal stability of immobilized proteins by measuring microbead mechanics.

Optimal immobilization of enzymes on porous microbeads enables the fabrication of highly active and stable heterogeneous biocatalysts to implement biocatalysis in synthetic and analytical chemistry. However, empirical procedures for enzyme immobilization still prevail over rational ones because there is an unmet need for more comprehensive characterization techniques that aid to understand and trace the immobilization process. Here, we present the use of atomic force spectroscopy (AFS) as an innovative solution to indirectly characterize immobilized proteins on porous materials and monitor the immobilization process in real time. We investigate the mechanical properties of porous agarose microbeads immobilizing proteins by indenting a colloidal probe (silica microparticle) into a single bead. AFS demonstrates that the binding of proteins to the solid matrix of an agarose microbead alters its stiffness. Interestingly, we discovered that irreversible and multivalent immobilizations that make microbeads stiffer also stabilize the immobilized proteins against the temperature. Hence, we propose atomic force spectroscopy as a useful technique to indirectly unravel the stability of the immobilized enzymes investigating the mechanics of the heterogenous biocatalysts as a solid biomaterial beyond the intrinsic mechanics of the proteins.

A quantitative study of the intracellular dynamics of fluorescently labelled glyco-gold nanoparticles via fluorescence correlation spectroscopy.

The dynamic behaviour of gold nanoparticles functionalised with glucose (Glc-Au NPs) has been studied here by means of fluorescence correlation spectroscopy (FCS). Meaningful data on the state of aggregation and dynamics of Glc-Au NPs fluorescently-labelled with HiLyte Fluor647 (Glc-Au-Hi NPs) in the intracellular environment were obtained. Moreover, the work presented here shows that FCS can be used to visualise the presence of single NPs or NP aggregates following uptake and to estimate, locally, NP concentrations within the cell. FCS measurements become possible after applying a "prebleaching" methodology, when the immobile NP fraction has been effectively removed and thus significant FCS data has been recorded. In this study, Glc-Au-Hi NPs have been incubated with HepG2 cells and their diffusion time in the intracellular environment has been measured and compared with their diffusion value in water and cell media.

Modulating the physicochemical and structural properties of gold-functionalized protein nanotubes through thiol surface modification.

Biomolecules are advantageous scaffolds for the synthesis and ordering of metallic nanoparticles. Rotavirus VP6 nanotubes possess intrinsic affinity to metal ions, a property that has been exploited to synthesize gold nanoparticles over them. The resulting nanobiomaterials have unique properties useful for novel applications. However, the formed nanobiomaterials lack of colloidal stability and flocculate, limiting their functionality. Here we demonstrate that it is possible to synthesize thiol-protected gold nanoparticles over VP6 nanotubes, which resulted in soluble nanobiomaterials. With this strategy, it was possible to modulate the size, colloidal stability, and surface plasmon resonance of the synthesized nanoparticles by controlling the content of the thiolated ligands. Two types of water-soluble ligands were tested, a small linear ligand, sodium 3-mercapto-1-propanesulfonate (MPS), and a bulky ligand, 5-mercaptopentyl ß-D-glucopyranoside (GlcC5SH). The synthesized nanobiomaterials had a higher stability in suspension, as determined by Z-potential measurements. To the extent of our knowledge, this is the first time that a rational strategy is developed to modulate the particular properties of metal nanoparticles in situ synthesized over a protein bioscaffold through thiol coating, achieving a high spatial and structural organization of nanoparticles in a single integrative hybrid structure.

Nanogels: Smart tools to enlarge the therapeutic window of gene therapy.

Gene therapy can potentially treat a great number of diseases, from cancer to rare genetic disorders. Very recently, the development and emergency approval of nucleic acid-based COVID-19 vaccines confirmed its strength and versatility. However, gene therapy encounters limitations due to the lack of suitable carriers to vectorize therapeutic genetic material inside target cells. Nanogels are highly hydrated nano-size crosslinked polymeric networks that have been used in many biomedical applications, from drug delivery to tissue engineering and diagnostics. Due to their easy production, tunability, and swelling properties they have called the attention as promising vectors for gene delivery. In this review, nanogels are discussed as vectors for nucleic acid delivery aiming to enlarge gene therapy's therapeutic window. Recent works highlighting the optimization of inherent transfection efficiency and biocompatibility are reviewed here. The importance of the monomer choice, along with the internal structure, surface decoration, and responsive features are outlined for the different transfection modalities. The possible sources of toxicological endpoints in nanogels are analyzed, and the strategies to limit them are compared. Finally, perspectives are discussed to identify the remining challenges for the nanogels before their translation to the market as transfection agents.

Determination of the optimal pH for doxorubicin encapsulation in polymeric micelles.

HYPOTHESIS: The anticancer drug doxorubicin hydrochloride (DX) shows a high solubility in aqueous media thanks to the positive charge in the ammonium group. This feature, however, affects the drug encapsulation in the hydrophobic domains of polymeric micelles (PMs) used for the targeted delivery of the drug. At basic pH, DX deprotonates but also acquires a negative charge in the phenolic groups of the anthracycline structure. Both the efficiency and the rate of encapsulation will be increased by choosing an appropriate pH such that the drug molecule is in neutral form. EXPERIMENTS: An optimal pH for the encapsulation of the DX in PMs based on commercial poloxamers and on the diblock copolymer methoxy-poly(ethylene glycol)17-b-poly(ε-caprolactone)9 was determined by fluorescence spectroscopy, following the time evolution of both the intensity ratio of the first and the second emission bands of DX and its fluorescence lifetime, both sensitive to the environment polarity. Intracellular delivery of PMs encapsulated drug was followed by Confocal Scanning Laser Microscopy (CSLM). Cell viability was assessed with the sulforhodamine B (SRB) assay. FINDINGS: By adjusting pH to 8.1 a high yield of incorporation of DX in the PMs was achieved coupled to an appreciable increase (one order of magnitude) in the drug encapsulation rate. In-vitro tests in selected cancer cell lines showed the slow release of the drug and a delay in the cytotoxic response in comparison to free DX as detected by CSLM and SRB assay. The proposed methodology paves the way for a greener, faster and more efficient encapsulation of DX in PMs.

ROS-Responsive 4D Printable Acrylic Thioether-Based Hydrogels for Smart Drug Release.

Reactive oxygen species (ROS) play a key role in several biological functions like regulating cell survival and signaling; however, their effect can range from beneficial to nondesirable oxidative stress when they are overproduced causing inflammation or cancer diseases. Thus, the design of tailor-made ROS-responsive polymers offers the possibility of engineering hydrogels for target therapies. In this work, we developed thioether-based ROS-responsive difunctional monomers from ethylene glycol/thioether acrylate (EGnSA) with different lengths of the EGn chain (n = 1, 2, 3) by the thiol-Michael addition click reaction. The presence of acrylate groups allowed their photopolymerization by UV light, while the thioether groups conferred ROS-responsive properties. As a result, smart PEGnSA hydrogels were obtained, which could be processed by four-dimensional (4D) printing. The mechanical properties of the hydrogels were determined by rheology, pointing out a decrease of the elastic modulus (G') with the length of the EG segment. To enhance the stability of the hydrogels after swelling, the EGnSA monomers were copolymerized with a polar monomer, 2-hydroxyethyl acrylate (HEA), leading to P[(EGnSA)x-co-HEAy] with improved compatibility in aqueous media, making it a less brittle material. Swelling properties of the hydrogels increased in the presence of hydrogen peroxide, a kind of ROS, reaching values of ≈130% for P[(EG3SA)7-co-HEA93] which confirms the stimuli-responsive properties. Then, the P[(EG3SA)x-co-HEAy] hydrogels were employed as matrixes for the encapsulation of a chemotherapeutic drug, 5-fluorouracil (5FU), which showed sustained release over time modulated by the presence of H2O2. Finally, the effect of the 5-FU release from P[(EG3SA)x-co-HEAy] hydrogels was tested in vitro with melanoma cancer cells B16F10, pointing out B16F10 growth inhibition values in the range of 40-60% modulated by the EG3SA percentage and the presence or absence of ROS agents, thus confirming their excellent ROS-responsive properties for the treatment of localized pathologies.

A study of complexation and biological fate of polyethyleneimine-siRNA polyplexes in vitro and in vivo by fluorescence correlation spectroscopy and positron emission tomography imaging.

A deeper knowledge on the formation and biological fate of polymer based gene vectors is needed for their translation into therapy. Here, polyplexes of polyethyleneimine (PEI) and silencing RNA (siRNA) are formed with theoretical N/P ratios of 2, 4 and 12. Fluorescence correlation spectroscopy (FCS) is used to study the formation of polyplexes from fluorescently labelled PEI and siRNA. FCS proves the presence of free PEI. From the analysis of the autocorrelation functions it was possible to determine the actual stoichiometry of polyplexes. FCS and fluorescence cross correlation spectroscopy (FCCS) are used to follow the fate of the polyplexes intracellularly. Polyplexes disassemble after 1 day inside cells. Positron emission tomography (PET) studies are conducted with radiolabelled polyplexes prepared with siRNA or PEI labelled with 2,3,5,6-tetrafluorophenyl 6-[18F]-fluoronicotinate ([18F]F-PyTFP). PET studies in healthy mice show that [18F]siRNA/PEI and siRNA/[18F]PEI polyplexes show similar biodistribution patterns with limited circulation in the bloodstream and accumulation in the liver. Higher activity for [18F]PEI in the kidney and bladder suggests the presence of free PEI.

Supramolecular citrate poly allylamine hydrochloride nanoparticles for citrate delivery and calcium oxalate nanocrystal dissolution.

HYPOTHESIS: Renal calculi (kidney stones) are mainly made by calcium oxalate and can cause different complications including malfunction of the kidney. The most important urinary stone inhibitors are citrate molecules. Unfortunately, the amount of citrate reaching the kidney after oral ingestion is low. We hypothesized that nanoparticles of polyallylamine hydrochloride (CIT-PAH) carrying citrate ions could simultaneously deliver citrates while PAH would complex oxalate triggering dissolution and removal of CaOx nanocrystals. EXPERIMENTS: We successfully prepared nanoparticles of citrate ions with polyallylamine hydrochloride (CIT-PAH), PAH with oxalate (OX-PAH) and characterize them by Small Angle X ray Scattering (SAXS), Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS) and NMR. Dissolution of CaOx nanocrystals in presence of CIT-PAH have been followed with Wide Angle Xray Scattering (WAXS), DLS and Confocal Raman Microscopy. Raman spectroscopy was used to study the dissolution of crystals in synthetic urine samples. The release of citrate from CIT-PAH was followed by diffusion NMR. Molecular dynamics (MD) simulations were carried out to study the interaction of CIT and OX ions with PAH. FINDINGS: CIT-PAH nanoparticles dissolves CaOx nanocrystals as shown by NMR, DLS, TEM and WAXS in water and by Raman spectroscopy in artificial human urine. WAXS and Raman show that the crystal structure of CaOx disappears in the presence of CIT-PAH. DLS shows that the time required for CaOX dissolution will depend on the concentration of CIT-PAH NPs. NMR proves that citrate ions are released from the CIT PAH NPs during CaOX dissolution, MD simulations showed that oxalates exhibit a stronger interaction for PAH than citrate, explaining the removal of oxalate ions and replacement of the citrate in the polymer nanoparticles.

Biocompatible cellulose nanocrystal-based Trojan horse enables targeted delivery of nano-Au radiosensitizers to triple negative breast cancer cells.

A hybrid cellulose-based programmable nanoplatform for applications in precision radiation oncology is described. Here, sugar heads work as tumor targeting moieties and steer the precise delivery of radiosensitizers, i.e. gold nanoparticles (AuNPs) into triple negative breast cancer (TNBC) cells. This "Trojan horse" approach promotes a specific and massive accumulation of radiosensitizers in TNBC cells, thus avoiding the fast turnover of small-sized AuNPs and the need for high doses of AuNPs for treatment. Application of X-rays resulted in a significant increase of the therapeutic effect while delivering the same dose, showing the possibility to use roughly half dose of X-rays to obtain the same radiotoxicity effect. These data suggest that this hybrid nanoplatform acts as a promising tool for applications in enhancing cancer radiotherapy effects with lower doses of X-rays.

Self-Assembled Oleic Acid-Modified Polyallylamines for Improved siRNA Transfection Efficiency and Lower Cytotoxicity.

Small interference RNA (siRNA) is a tool for gene modulation, which can silence any gene involved in genetic disorders. The potential of this therapeutic tool is hampered by RNA instability in the blood stream and difficulties to reach the cytosol. Polyamine-based nanoparticles play an important role in gene delivery. Polyallylamine hydrochloride (PAH) is a polycation displaying primary amines that can be easily chemically modified to match the balance between cell viability and siRNA transfection. In this work, PAH has been covalently functionalized with oleic acid at different molar ratios by carbodiimide chemistry. The substituted polymers form polyplexes that keep positive surface charge and fully encapsulate siRNA. Oleic acid substitution improves cell viability in the pulmonary cell line A549. Moreover, 6 and 14% of oleic acid substitution show an improvement in siRNA transfection efficiency. CD47 is a ubiquitous protein which acts as "don't eat me signal." SIRPα protein of macrophages recognizes CD47, leading to tumor cell phagocytosis by macrophages. By knocking down CD47 with siRNA, cancer cells become vulnerable to be eliminated by the immune system. PAH-oleic acid substitutes show high efficacy in silencing the CD47 protein, making them a potential candidate for immunotherapy.