PExM: polyplex expansion microscopy for cell trafficking studies.

Nanomedicine is a field at the intersection of nanotechnology and medicine, promising due to its potential to revolutionize healthcare. Despite its long trajectory, there is still a long road ahead for its full development, and smart design of nanomedicines is still a challenge. Among other problems, this is due to the scarcity of tools available for the precise visualization and comprehension of nano-bio interactions, impeding progress towards the clinical phase. One of the developed tools that stands out to be a strong nanoscopy technique for studying nano-delivery systems within cellular environments is expansion microscopy (ExM). This technique was used for tissue and cell expansion and most recently for lipid molecule expansion inside cells. Herein, we present for the first time polyplex expansion microscopy (PExM); a comprehensive examination of ExM as an already developed technique, but adapted for expanding polymer based nanocarriers, in particular polyplexes within cells, allowing the analysis of their trafficking. With our method set up, PExM will be extensively used for the study of polyplex nanoparticle cell trafficking, becoming a high-resolution technique which can also be applied to primary amine containing polymeric nanoparticles without requiring expensive super-resolution microscopes.

Nucleic acid-loaded poly(beta-aminoester) nanoparticles for cancer nano-immuno therapeutics: the good, the bad, and the future.

Immunotherapy has emerged as a promising approach to cancer treatment, offering improved survival rates and enhanced patients' quality of life. However, realizing the full potential of immunotherapy in clinical practice remains a challenge, as there is still plenty of room for modulating the complexity of the human immune system in favor of an antitumor immunogenicity. Nanotechnology, with its unique properties, holds promise in augmenting the efficacy of cancer immunotherapies in biotherapeutic protection and site- and time-controlled delivery of the immune modulator biologicals. Polymeric nanoparticles are promising biomaterials among different nanocarriers thanks to their robustness, versatility, and cost-efficient design and production. This perspective paper overviews critical concepts in nanometric advanced delivery systems applied to cancer immunotherapy. We focus on a detailed exploration of the current state of the art and trends in using poly(beta-aminoester) (pBAE) polymers for nucleic acid-based antitumor immunotherapies. Through different examples of the use of pBAE polymers reported in the literature, we revise the main advantages these polymers offer and some challenges to overcome. Finally, the paper provides insights and predictions on the path toward the clinical implementation of cancer nano-immunotherapies, highlighting the potential of pBAE polymers for advancements in this field.

Liver-targeted nanoparticles delivering nitric oxide reduce portal hypertension in cirrhotic rats.

Nitric oxide (NO) is a small vasodilator playing a key role in the pathogenesis of portal hypertension. Here, we assessed the potential therapeutic effect of a NO donor targeted to the liver by poly(beta-amino ester) nanoparticles (pBAE NPs) in experimental cirrhosis. Retinol-functionalized NO donor pBAE NPs (Ret pBAE NPs) were synthetized with the aim of actively targeting the liver. Administration of Ret pBAE NPs resulted in uptake and transfection by the liver and spleen. NPs were not found in other organs or the systemic circulation. Treatment with NO donor Ret pBAE NPs (30 mg/ kg body weight) significantly decreased aspartate aminotransferase, lactate dehydrogenase and portal pressure (9.75 ± 0.64 mmHg) compared to control NPs (13.4 ± 0.53 mmHg) in cirrhotic rats. There were no effects on mean arterial pressure and cardiac output. Liver-targeted NO donor NPs reduced collagen fibers and steatosis, activation of hepatic stellate cells and mRNA expression of profibrogenic and proinflammatory genes. Finally, Ret pBAE NPs displayed efficient transfection in human liver slices. Overall, liver-specific NO donor NPs effectively target the liver and mitigated inflammation and portal hypertension in cirrhotic rats. The use of Ret pBAE may prove to be an effective therapeutic strategy to treat advanced liver disease.

Engineering oncogene-targeted anisamide-functionalized pBAE nanoparticles as efficient lung cancer antisense therapies.

Non-small cell lung cancer (NSCLC) is one of the leading causes of worldwide death, mainly due to the lack of efficient and safe therapies. Currently, NSCLC standard of care for consist on the use of traditional chemotherapeutics, non-selectively distributed through the whole body, thus causing severe side effects while not achieving high efficacy outcomes. Consequently, the need of novel therapies, targeted to modify specific subcellular routes aberrantly expressed only in tumor cells is still urgent. In this context, the delivery of siRNAs that can know-down overexpressed oncogenes, such as mTOR, could become the promised targeted therapy. However, siRNA effective delivery remains a challenge due to its compromised stability in biological fluids and its inability to cross biological and plasmatic membranes. Therefore, polymeric nanoparticles that efficiently encapsulate siRNAs and are selectively targeted to tumor cells could play a pivotal role. Accordingly, we demonstrate in this work that oligopeptide end-modified poly(beta aminoester) (OM-pBAE) polymers can efficiently complex siRNA in small nanometric particles using very low polymer amounts, protecting siRNA from nucleases attack. These nanoparticles are stable in the presence of serum, advantageous fact in terms of in vivo use. We also demonstrated that they efficiently transfect cells in vitro, in the presence of serum and are able to knock down target gene expression. Moreover, we demonstrated their antitumor efficacy by encapsulating mTOR siRNA, as a model antisense therapy, which showed specific lung tumor cell growth inhibition in vitro and in vivo. Finally, through the addition of anisamide functionalization to the surface of the nanoparticles, we proved that they become selective to lung tumor cells, while not affecting healthy cells. Therefore, our results are a first step in the discovery of a tumor cell-targeted efficient silencing nanotherapy for NSCLC patients survival improvement.

Novel α-mannose-functionalized poly(ß-amino ester) nanoparticles as mRNA vaccines with increased antigen presenting cell selectivity in the spleen.

mRNA vaccination has emerged as a prominent therapy for the future of medicine. Despite the colossal advance in this technology and worldwide efficacy proof (ca. COVID vaccines), mRNA carriers still lack cell/tissue specificity, leading to possible side effects, and reduced efficacy among others. Herein we make use of the ubiquitous affinity of antigen-presenting cells (APC)s for glycosides to achieve specific targeting. To achieve this goal, we designed a new generation of α-mannosyl functionalized oligopeptide-terminated poly(ß-aminoester). Fine formulation of these polymers with mRNA resulted in nanoparticles decorated with surface-exposed α-mannoses with sizes around 180 nm and positive surface charge. Notably, these particles maintained their properties after freeze-drying and subsequent redispersion. Finally, our mRNA carriers preferentially targeted and transfected APCs in vitro and in vivo. In conclusion, we demonstrated, at a preclinical level, that the mannose functionalization enables more selective targeting of APCs and, thus, these polymer and nanoparticles are candidates for a new generation of mRNA immunotherapy vaccines.

Ammonium trifluoroborate-modified poly(ß-aminoesters): A case study for PET-guided in vivo pharmacokinetic studies of a non-viral gene delivery system.

Nucleic acid-based therapies have become a game-changing player in our way of conceiving pharmacology. Nevertheless, the inherent lability of the phosphodiester bond of the genetic material with respect to the blood nucleases severely hampers its delivery in naked form, therefore making it necessary to use delivery vectors. Among the potential non-viral vectors, polymeric materials such as the poly(ß-aminoesters) (PBAEs) stand out as promising gene carriers thanks to their ability to condense nucleic acids in the form of nanometric polyplexes. To keep advancing these systems into their translational preclinical phases, it would be highly valuable to gain accurate insights of their in vivo pharmacokinetic profile. We envisaged that positron emission tomography (PET)-guided imaging could provide us with both, an accurate assessment of the biodistribution of PBAE-derived polyplexes, as well shed light on their clearance process. In this sense, taking advantage of the efficient [19F]-to-[18F]­fluorine isotopic exchange presented by the ammonium trifluoroborate (AMBF3) group, we have designed and synthesized a new 18F-PET radiotracer based on the chemical modification of a linear poly(ß-aminoester). As proof of concept, the incorporation of the newly developed 18F-PBAE into a model nanoformulation was shown to be fully compatible with the formation of the polyplexes, their biophysical characterization, and all their in vitro and in vivo functional features. With this tool in hand, we were able to readily obtain key clues about the pharmacokinetic behavior of a series of oligopeptide-modified PBAEs (OM-PBAEs). The observations described in this study allow us to continue supporting these polymers as an outstanding non-viral gene delivery vector for future applications.

Biomineralization in Three-Dimensional Scaffolds Based on Bacterial Nanocellulose for Bone Tissue Engineering: Feature Characterization and Stem Cell Differentiation.

Bacterial nanocellulose (BNC) has a negative surface charge in physiological environments, which allows the adsorption of calcium ions to initiate the nucleation of different calcium phosphate phases. The aim of this study was to investigate different methods of mineralization in three-dimensional microporous bacterial nanocellulose with the intention of mimicking the composition, structure, and biomechanical properties of natural bone. To generate the 3D microporous biomaterial, porogen particles were incorporated during BNC fermentation with the Komagataeibacter medellinensis strain. Calcium phosphates (CPs) were deposited onto the BNC scaffolds in five immersion cycles, alternating between calcium and phosphate salts in their insoluble forms. Scanning electron microscopy (SEM) showed that the scaffolds had different pore sizes (between 70 and 350 µm), and their porous interconnectivity was affected by the biomineralization method and time. The crystals on the BNC surface were shown to be rod-shaped, with a calcium phosphate ratio similar to that of immature bone, increasing from 1.13 to 1.6 with increasing cycle numbers. These crystals also increased in size with an increasing number of cycles, going from 25.12 to 35.9 nm. The main mineral phase observed with X-ray diffraction was octacalcium dihydrogen hexakis phosphate (V) pentahydrate (OCP). In vitro studies showed good cellular adhesion and high cell viability (up to 95%) with all the scaffolds. The osteogenic differentiation of human bone marrow mesenchymal stem cells on the scaffolds was evaluated using bone expression markers, including alkaline phosphatase, osteocalcin, and osteopontin. In conclusion, it is possible to prepare 3D BNC scaffolds with controlled microporosity that allow osteoblast adhesion, proliferation, and differentiation.

Unravelling the role of individual components in pBAE/polynucleotide polyplexes in the synthesis of tailored carriers for specific applications: on the road to rational formulations.

Oligopeptide end-modified poly(ß-amino ester)s (OM-pBAEs) offer a means for the effective implementation of gene therapeutics in the near future. A fine-tuning of OM-pBAEs to meet application requirements is achieved by the proportional balance of oligopeptides used and provide gene carriers with high transfection efficacy, low toxicity, precise targeting, biocompatibility, and biodegradability. Understanding the influence and conformation of each building block at molecular and biological levels is therefore pivotal for further development and improvement of these gene carriers. Herein, we unmask the role of individual OM-pBAE components and their conformation in OM-pBAE/polynucleotide nanoparticles using a combination of fluorescence resonance energy transfer, enhanced darkfield spectral microscopy, atomic force microscopy, and microscale thermophoresis. We found that modifying the pBAE backbone with three end-terminal amino acids produces unique mechanical and physical properties for each combination. Higher adhesion properties are seen with arginine and lysine-based hybrid nanoparticles, while histidine provides an advantage in terms of construct stability. Our results shed light on the high potential of OM-pBAEs as gene delivery vehicles and provide insights into the influence of the nature of surface charges and the chemical nature of the pBAE modifications on their paths towards endocytosis, endosomal escape, and transfection.

Effect of surface functionalization and loading on the mechanical properties of soft polymeric nanoparticles prepared by nano-emulsion templating.

Drug and gene delivery systems based on polymeric nanoparticles offer a greater efficacy and a reduced toxicity compared to traditional formulations. Recent studies have evidenced that their internalization, biodistribution and efficacy can be affected, among other factors, by their mechanical properties. Here, we analyze by means of Atomic Force Microscopy force spectroscopy how composition, surface functionalization and loading affect the mechanics of nanoparticles. For this purpose, nanoparticles made of Poly(lactic-co-glycolic) (PLGA) and Ethyl cellulose (EC) with different functionalizations and loading were prepared by nano-emulsion templating using the Phase Inversion Composition method (PIC) to form the nano-emulsions. A multiparametric nanomechanical study involving the determination of the Young's modulus, maximum deformation and breakthrough force was carried out. The obtained results showed that composition, surface functionalization and loading affect the nanomechanical properties in a different way, thus requiring, in general, to consider the overall mechanical properties after the addition of a functionalization or loading. A graphical representation method has been proposed enabling to easily identify mechanically equivalent formulations, which is expected to be useful in the development of soft polymeric nanoparticles for pre-clinical and clinical use.

Efficient extracellular vesicles freeze-dry method for direct formulations preparation and use.

Despite the great knowledge achieved in the field of extracellular vesicles (EVs), the short lifetime of EVs liquid formulation still hampers the transfer of EVs technology to clinical applications. In this context, freeze-dried EVs would be advantageous thanks to the enhanced stability of solid formulations. Although some previous attempts have already been reported, the efficiency of EVs lyophilization methodologies used remains insufficient, and the characterization of the resulting EVs is still incomplete. The current work aims to describe an alternative and easy-to-be-applied methodology for EVs lyophilization. The use of sucrose as lyoprotectant at 8.5%wt improved the cryopreservation efficiency. After the subsequent cycles of freeze-drying, properties such as size, morphology, purity, EVs specific markers, biocompatibility and the maintenance of their functionality were confirmed in freeze-dried EVs samples. To sum up, we have designed a methodology for the lyophilization of extracellular vesicles that enables the preservation of the physicochemical properties and functionality of EVs.

Complex pBAE Nanoparticle Cell Trafficking: Tracking Both Position and Composition Using Super Resolution Microscopy.

Nanomedicine emerged some decades ago with the hope to be the solution for most unmet medical needs. However, tracking materials at nanoscale is challenging to their reduced size, below the resolution limit of most conventional techniques. In this context, we propose the use of direct stochastic optical reconstruction microscopy (dSTORM) to study time stability and cell trafficking after transfection of oligopeptide end-modified poly(ß-aminoester) (OM-pBAE) nanoparticles. We selected different combinations of cationic end oligopeptides (arginine - R; histidine - H; and lysine - K) among polymer libraries, since the oligopeptide combination demonstrated to be useful for different applications, such as vaccination and gene silencing. We demonstrate that their time evolution as well as their cell uptake and trafficking are dependent on the oligopeptide. This study opens the pave to broad mechanistic studies at nanoscale that could enable a rational selection of specific pBAE nanoparticles composition after determining their stability and cell trafficking.

Role of Survivin in Bladder Cancer: Issues to Be Overcome When Designing an Efficient Dual Nano-Therapy.

Bladder cancer is the 10th most diagnosed cancer, with almost 10 M cancer deaths last year worldwide. Currently, chemotherapy is widely used as adjuvant therapy after surgical transurethral resection. Paclitaxel (PTX) is one of the most promising drugs, but cancer cells acquire resistance, causing failure of this treatment and increasing the recurrence of the disease. This poor chemotherapeutic response has been associated with the overexpression of the protein survivin. In this work, we present a novel dual nano-treatment for bladder cancer based on the hypothesis that the inhibition of survivin in cancer cells, using a siRNA gene therapy strategy, could decrease their resistance to PTX. For this purpose, two different polymeric nanoparticles were developed to encapsulate PTX and survivin siRNA independently. PTX nanoparticles showed sizes around 150 nm, with a paclitaxel loading of around 1.5%, that produced sustained tumor cell death. In parallel, siRNA nanoparticles, with similar sizes and loading efficiency of around 100%, achieved the oligonucleotide transfection and knocking down of survivin expression that also resulted in tumor cell death. However, dual treatment did not show the synergistic effect expected. The root cause of this issue was found to be the cell cycle arrest produced by nuclear survivin silencing, which is incompatible with PTX action. Therefore, we concluded that although the vastly reported role of survivin in bladder cancer, its silencing does not sensitize cells to currently applied chemotherapies.

Preclinical Assessment of a Gene-Editing Approach in a Mouse Model of Mitochondrial Neurogastrointestinal Encephalomyopathy.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is a rare disease caused by recessive mutations in the TYMP gene, which encodes the enzyme thymidine phosphorylase (TP). In this study, the efficient integration of a TYMP transgene into introns of the Tymp and Alb loci of hepatocytes in a murine model of MNGIE was achieved by the coordinated delivery and activity of CRISPR/Cas9 and a TYMP cDNA. CRISPR/Cas9 was delivered either as mRNA using lipid nanoparticle (LNP) or polymeric nanoparticle, respectively, or in an AAV2/8 viral vector; the latter was also used to package the TYMP cDNA. Insertion of the cDNA template downstream of the Tymp and Alb promoters ensured transgene expression. The best in vivo results were obtained using LNP carrying the CRISPR/Cas9 mRNAs. Treated mice showed a consistent long-term (1 year) reduction in plasma nucleoside (thymidine and deoxyuridine) levels that correlated with the presence of TYMP mRNA and functional enzyme in liver cells. In mice with an edited Alb locus, the transgene produced a hybrid Alb-hTP protein that was secreted, with supraphysiological levels of TP activity detected in the plasma. Equivalent results were obtained in mice edited at the Tymp locus. Finally, some degree of gene editing was found in animals treated only with AAV vectors containing the DNA templates, in the absence of nucleases, although there was no impact on plasma nucleoside levels. Overall, these results demonstrate the feasibility of liver-directed genome editing in the long-term correction of MNGIE, with several advantages over other methods.

Synthesis and Characterization of mRNA-Loaded Poly(Beta Aminoesters) Nanoparticles for Vaccination Purposes.

Vaccination has been one of the major successes of modern society and is indispensable in controlling and preventing disease. Traditional vaccines were composed of entire or fractions of the infectious agent. However, challenges remain, and new vaccine technologies are mandatory. In this context, the use of mRNA for immunizing purposes has shown an enhanced performance, as demonstrated by the speedy approval of two mRNA vaccines preventing SARS-CoV-2 infection. Beyond success in preventing viral infections, mRNA vaccines can also be used for therapeutic cancer applications. Nevertheless, the instability of mRNA and its fast clearance from the body due to the presence of nucleases makes its naked delivery not possible. In this context, nanomedicines, and specifically polymeric nanoparticles, are critical mRNA delivery systems. Thus, the aim of this article is to describe the protocol for the formulation and test of an mRNA vaccine candidate based on the proprietary polymeric nanoparticles. The synthesis and chemical characterization of the poly(beta aminoesters) polymers used, their complexation with mRNA to form nanoparticles, and their lyophilization methodology will be discussed here. This is a crucial step for decreasing storage and distribution costs. Finally, the required tests to demonstrate their capacity to in vitro transfect and mature model dendritic cells will be indicated. This protocol will benefit the scientific community working on vaccination because of its high versatility that enables these vaccines to prevent or cure a wide variety of diseases.

Electrostatic Coating of Viral Particles for Gene Delivery Applications in Muscular Dystrophies: Influence of Size on Stability and Antibody Protection.

BACKGROUND: Duchenne Muscular Dystrophy (DMD) is one of the most common muscular dystrophies, caused by mutated forms of the dystrophin gene. Currently, the only treatment available is symptoms management. Novel approximations are trying to treat these patients with gene therapy, namely, using viral vectors. However, these vectors can be recognized by the immune system decreasing their therapeutic activity and making impossible a multidose treatment due to the induction of the humoral immunity following the first dose. OBJECTIVE: Our objective is to demonstrate the feasibility of using a hybrid vector to avoid immune clearance, based on the electrostatic coating of adeno-associated virus (AAVs) vectors with our proprietary polymers. METHODS: We coated model adeno-associated virus vectors by electrostatic interaction of our cationic poly (beta aminoester) polymers with the viral anionic capsid and characterized biophysical properties. Once the nanoformulations were designed, we studied their in vivo biodistribution by bioluminescence analysis and we finally studied the capacity of the polymers as potential coatings to avoid antibody neutralization. RESULTS: We tested two polymer combinations and we demonstrated the need for poly(ethylene glycol) addition to avoid vector aggregation after coating. In vivo biodistribution studies demonstrated that viral particles are located in the liver (short times) and also in muscles (long times), the target organ. However, we did not achieve complete antibody neutralization shielding using this electrostatic coating. CONCLUSIONS: The null hypothesis stands: although it is feasible to coat viral particles by electrostatic interaction with a proprietary polymer, this strategy is not appropriate for AAVs due to their small size, so other alternatives are required as a novel treatment for DMD patients.

Extracellular Vesicles and Their Current Role in Cancer Immunotherapy.

Extracellular vesicles (EVs) are natural particles formed by the lipid bilayer and released from almost all cell types to the extracellular environment both under physiological conditions and in presence of a disease. EVs are involved in many biological processes including intercellular communication, acting as natural carriers in the transfer of various biomolecules such as DNA, various RNA types, proteins and different phospholipids. Thanks to their transfer and targeting abilities, they can be employed in drug and gene delivery and have been proposed for the treatment of different diseases, including cancer. Recently, the use of EVs as biological carriers has also been extended to cancer immunotherapy. This new technique of cancer treatment involves the use of EVs to transport molecules capable of triggering an immune response to damage cancer cells. Several studies have analyzed the possibility of using EVs in new cancer vaccines, which represent a particular form of immunotherapy. In the literature there are only few publications that systematically group and collectively discuss these studies. Therefore, the purpose of this review is to illustrate and give a partial reorganization to what has been produced in the literature so far. We provide basic notions on cancer immunotherapy and describe some clinical trials in which therapeutic cancer vaccines are tested. We thus focus attention on the potential of EV-based therapeutic vaccines in the treatment of cancer patients, overviewing the clinically relevant trials, completed or still in progress, which open up new perspectives in the fight against cancer.

Cancer immunotherapies revisited: state of the art of conventional treatments and next-generation nanomedicines.

Nowadays, the landscape of cancer treatments has broadened thanks to the clinical application of immunotherapeutics. After decades of failures, cancer immunotherapy represents an exciting alternative for those patients suffering from a wide variety of cancers, especially for those skin cancers, such as the early stages of melanoma. However, those cancers affecting internal organs still face a long way to success, because of the poor biodistribution of immunotherapies. Here, nanomedicine appears as a hopeful strategy to modulate the biodistribution aiming at target organ accumulation. In this way, efficacy will be improved, while reducing the side effects at the same time. In this review, we aim to highlight the most promising cancer immunotherapeutic strategies. From monoclonal antibodies and their traditional use as targeted therapies to their current use as immune checkpoint inhibitors; as well as adoptive cell transfer therapies; oncolytic viruses, and therapeutic cancer vaccination. Then, we aim to discuss the important role of nanomedicine to improve the performance of these immunotherapeutic tools to finally review the already marketed nanomedicine-based cancer immunotherapies.

Blood-brain barrier dysfunction in hemorrhagic transformation: a therapeutic opportunity for nanoparticles and melatonin.

Stroke is the second leading cause of death worldwide, estimated that one-sixth of the world population will suffer it once in their life. The most common type of this medical condition is the ischemic stroke (IS), produced by a thrombotic or embolic occlusion of a major cerebral artery or its branches, leading to the formation of a complex infarct region caused by oxidative stress, excitotoxicity, and endothelial dysfunction. Nowadays, the immediate treatment for IS involves thrombolytic agents or mechanical thrombectomy, depending on the integrity of the blood-brain barrier (BBB). A common stroke complication is the hemorrhagic transformation (HT), which consists of bleeding into the ischemic brain area. Currently, better treatments for IS are urgently needed. As such, the neurohormone melatonin has been proposed as a good candidate due to its antioxidant, anti-inflammatory, and neuroprotective effects, particularly against lipid peroxidation and oxidative stress during brain ischemia. Here, we proposed to develop intravenous or intranasal melatonin nanoformulation to specifically target the brain in patients with stroke. Nowadays, the challenge is to find a formulation able to cross the barriers and reach the target organ in an effective dose to generate the pharmacological effect. In this review, we discuss the current literature about stroke pathophysiology, melatonin properties, and its potential use in nanoformulations as a novel therapeutic approach for ischemic stroke.

Glycyrrhetinic Acid-Functionalized Mesoporous Silica Nanoparticles for the Co-Delivery of DOX/CPT-PEG for Targeting HepG2 Cells.

A pH-triggered mesoporous silica nanoparticle (MSN)-based nano-vehicle for the dual delivery of doxorubicin (DOX)/camptothecin-PEG (CPT-PEG) has been prepared. To enhance its selectivity, the nanoparticles were decorated with glycyrrhetinic acid (GA) to target HepG2 cells. The highly insoluble CPT was derivatized with a reductive-cleavable PEG chain to improve its loading within the MSN. The preparation of these particles consisted of four steps. First, CPT-PEG was loaded within the pores of the MSN. Then, dihydrazide polyethylene glycol chains were introduced onto the surface of an aldehyde-functionalized MSN by means of a hydrazone bond. Afterwards, DOX was covalently attached to the other end of the dihydrazide polyethylene glycol chains. Finally, the resulting nanoparticles were decorated with GA by formation of an imine bond between the amino group of DOX and a benzaldehyde-GA derivative. The system was stable at physiological conditions and the release of both drugs was negligible. However, at acidic pH, a burst release of DOX and a gradual release of CPT-PEG takes place. GA-decorated drug delivery systems (DDS) selectively internalizes into HepG2. In vitro tests demonstrated that this system shows a great cytotoxicity towards HepG2 cells. Furthermore, glutathione cleavage of CPT prodrug assures the formation of free CPT leading to a synergistic effect in combination with DOX.

Functionalized PLGA nanoparticles prepared by nano-emulsion templating interact selectively with proteins involved in the transport through the blood-brain barrier.

During the last few decades, extensive efforts has been made to design nanocarriers to transport drugs into the central nervous system (CNS). However, its efficacy is limited due to the presence of the Blood-Brain Barrier (BBB) which greatly reduces drug penetration making Drug Delivery Systems (DDS) necessary. Polymeric nanoparticles (NPs) have been reported to be appropriate for this purpose and in particular, poly(lactic-co-glycolic acid) (PLGA) has been used for its ability to entrap small molecule drugs with great efficiency and the ease with which it functionalizes NPs. Despite the fact that their synthetic identity has been studied in depth, the biological identity of such manufactured polymers still remains unknown as does their biodistribution and in vivo fate. This biological identity is a result of their interaction with blood proteins, the so-called "protein corona" which tends to alter the behavior of polymeric nanoparticles in the body. The aim of the present research is to identify the proteins bounded to polymeric nanoparticles designed to selectively interact with the BBB. For this purpose, four different PLGA NPs were prepared and analyzed: (i) "PLGA@Drug," in which a model drug was encapsulated in its core; (ii) "8D3-PLGA" NPs where the PLGA surface was functionalized with a monoclonal anti-transferrin receptor antibody (8D3 mAb) in order to specifically target the BBB; (iii) "8D3-PLGA@Drug" in which the PLGA@Drug surface was functionalized using the same antibody described above and (iv) bare PLGA NPs which were used as a control. Once the anticipated protein corona NPs were obtained, proteins decorating both bare and functionalized PLGA NPs were isolated and analyzed. Apart from the indistinct interaction with PLGA NPs with the most abundant serum proteins, specific proteins could also be identified in the case of functionalized PLGA NPs. These findings may provide valuable insight into designing novel vehicles based on PLGA NPs for crossing the BBB.