Polymeric nanocarriers for nose-to-brain drug delivery in neurodegenerative diseases and neurodevelopmental disorders

Neurodegenerative diseases are progressive conditions that affect the neurons of the central nervous system (CNS) and result in their damage and death. Neurodevelopmental disorders include intellectual disability, autism spectrum disorder, and attention-deficit/hyperactivity disorder and stem from the disruption of essential neurodevelopmental processes. The treatment of neurodegenerative and neurodevelopmental conditions, together affecting ∼120 million people worldwide, is challenged by the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier that prevent the crossing of drugs from the systemic circulation into the CNS. The nose-to-brain pathway that bypasses the BBB and increases the brain bioavailability of intranasally administered drugs is promising to improve the treatment of CNS conditions. This pathway is more efficient for nanoparticles than for solutions, hence, the research on intranasal nano-drug delivery systems has grown exponentially over the last decade. Polymeric nanoparticles have become key players in the field owing to the high design and synthetic flexibility. This review describes the challenges faced for the treatment of neurodegenerative and neurodevelopmental conditions, the molecular and cellular features of the nasal mucosa and the contribution of intranasal nano-drug delivery to overcome them. Then, a comprehensive overview of polymeric nanocarriers investigated to increase drug bioavailability in the brain is introduced.

Self-assembling dendrimers for biomedical applications / 中国药科大学学报

@#Dendrimers, a special class of synthetic polymers known for their well-defined ramified structures and unique multivalent cooperativity, hold great promise for various biomedical applications. However, preparation of defect-free dendrimers of high-generation on a large scale remains challenging because of the tedious and time-consuming synthesis as well as difficult purification. To overcome these limitations, an alternative strategy based on self-assembling approach has been developed to construct supramolecular dendrimers using small amphiphilic dendrimer-building units. By virtue of the amphiphilic nature, these small dendrimer-building units self-assemble and form large non-covalent supramolecular dendritic structures that mimic high-generation covalent dendrimers. Here, we present a brief overview of the supramolecular dendrimers developed in our group for the delivery of nucleic acid therapeutics, anticancer drug and imaging agents.

Pró-Fármacos dendriméricos potencialmente ativos em Malária e Tuberculose: Síntese e avaliação da atividade biológica / Dendrimeric prodrugs potentially active in malaria and tuberculosis: Synthesis and evaluation of biological activity

HIV/AIDS, tuberculose, malária e as doenças tropicais negligenciadas representam uma grande preocupação em Saúde em muitas regiões do mundo. Os fármacos disponíveis para o tratamento apresentam diversos problemas, tais como toxicidade e resistência ao parasita. Mesmo com esse triste panorama, o investimento em pesquisa nessa área é, ainda, pouco significativo. Assim, dentre os métodos de modificação molecular para melhorar propriedades farmacêuticas, farmacocinéticas e/ou farmacodinâmica de compostos bioativos destaca-se a latenciação. Já os dendrímeros vêm despertando interesse em aplicações biológicas, principalmente como transportadores de fármacos, além de atuarem como transportadores de genes, imagem em diagnóstico e compostos com ação per se. Face ao exposto e tendo em vista o caráter promissor dos dendrímeros como sistemas de drug delivery, o objetivo deste trabalho foi a síntese de pró-fármacos dendriméricos potencialmente ativos em malária e tuberculose. Os dendrímeros de Bis-MPA (gerações 0, 1 e 2) foram sintetizados pelo grupo do Professor Scott Grayson, da Tulane University (EUA). No Brasil, foram feitas as funcionalizações destes compostos, através do acoplamento do ácido succínico (que funciona como espaçante) e as moléculas ativas. Selecionaram-se as seguintes substâncias: (1) primaquina, com ação antimalárica e (2) isoniazida, de ação nos primeiros estágios da tuberculose. Foram sintetizados os pró-fármacos dendriméricos de isoniazida nas gerações 0 e 1 (G0-Iso e G1-Iso), e primaquina nas gerações 0, 1 e 2 (G0-Pq, G1-Pq e G2Pq). Importante mencionar que os resultados de Ressonância Magnética e Nuclear de 1H e de 13C demostraram as obtenções dos respectivos produtos, porém contendo impurezas. Já a análise do resultado proveniente da espectrometria de massas do composto G0-Iso revelou a presença de um subproduto ciclizado da isonizaida succinoilada (CIso-Suc), o qual pode ser um potencial pró-fármaco ou apresentar atividade per se. Como não se conhece este composto, o laboratório coordenado pela Profas Elizabeth Igne Ferreira e Jeanine Giarolla manifestou interesse em pesquisa-lo, principalmente quanto suas propriedades físico- químicas, bem como quanto à atividade biológica. Assim, utilizando metodologia analítica previamente estabelecida para o G0-Iso, os estudos de estabilidade química da CIso-Suc, em diferentes valores de pH, demonstraram a capacidade da forma ciclizada em se converter no protótipo Iso-Suc, majoritariamente em pH 7,4 e 8,5. Como perspectivas, destaca-se a avaliação da estabilidade enzimática deste potencial derivado. Ressalta-se, ainda, a a avaliação da respectiva atividade antimicobacteriana. Em relação aos pró-fármacos, as necessidades de aprimoramentos das sínteses são, também, evidenciadas. Uma vez sintetizados e caracterizados, estes últimos derivados serão avaliados quanto à atividade biológica. Ademais, estudos computacionais, sobretudo simulações de docking molecular, foram desenvolvidos com intuito de se entender o modo de interação de alguns compostos com alvos biológicos pré-determinados

HIV/AIDS, tuberculosis, malaria and neglected diseases are a major health concern in many regions of the world. The drugs available present various problems, such as toxicity and parasite resistance. Even with this sad outlook, research investment in this area is still insignificant. Among the molecular modification methods to improve the pharmaceutical, pharmacokinetic and/or pharmacodynamic properties we stands out prodrug design. On the other hand, dendrimers are arousing interest in biological applications, mainly as drug carriers, besides gene delivery, diagnostic imaging, as well as acting as compounds with activity per se. Considering that, added to the promising dendrimer drug delivery features, the aim of this study was to synthesize potentially active dendrimer prodrugs in malaria and tuberculosis. Bis-MPA dendrimers (generations 0, 1 and 2) were synthesized by the group of Professor Scott Grayson of Tulane University (USA). Herein in Brazil, the compounds were functionalized by coupling succinic acid (spacer group), as well as the active molecules. We selected the following substances: (1) primaquine, with antimalarial action and (2) isoniazid, acting in the early stages of tuberculosis. Isoniazid dendrimer prodrugs were synthesized generations 0 and 1 (G0-Iso and G1-Iso), and primaquine in generations 0, 1 and 2 (G0-Pq, G1-Pq and G2-Pq). It is important to mention that the results related to Nuclear and Magnetic Resonance 113C showed chemical structures features, however with impurities. Analysis of the mass spectrometry regarding G0-Iso has revealed the presence of a cyclized by-product of succinylated isonized (CIso-Suc), which may be a potential prodrug or may presentactivity itself. Using the analytical methodology performed for G0-Iso, ICso-Suc demonstrated its ability to convert the Iso-Suc prototype at different pH values, especially at pH 7.4 and 8.5. As perspectives, we highlight the determinations of the chemical stability of ICsoSuc at pH 1.5 and 6.0, as well as the evaluation of the enzymatic stability. We will also investigate the respective antimicobacterial activities. Regarding prodrugs, the needs for synthesis enhancements are also necessary. Once synthesized and characterized, these latter derivatives will be evaluated for biological activity. Moreover, computational studies, especially molecular docking simulations, were developed in order to understand the mode of interaction of some compounds with predetermined biological targets

Application of dendrimer-based siRNA delivery systems / 中国药科大学学报

@#Small interfering RNA-based RNA interference(RNAi)is an emerging treatment which has attracted more and more attention from both academia and industry. Studies on clinical translation of siRNA are popular in biomedical field, where safe and efficient carriers are necessary. As novel drug/gene vectors, dendrimers are widely used in siRNA delivery due to their unique and precise structure, multiple terminal groups and nano-sized chemophysical properties. Here, we present an overall view of current studies on dendrimer-based siRNA delivery systems, with the aim to provide an understanding of future siRNA therapeutics which could be used in clinic.

Sistemas de nanopartículas poliméricas II: estructura, métodos de elaboración, características, propiedades, biofuncionalización y tecnologías de auto-ensamblaje capa por capa (layer-by-layer self-assembly) / Polymeric nanoparticle systems: structure, elaboration methods, characteristics, properties, biofunctionalization and self-assembly layer by layer technologies

Los materiales poliméricos han sido ampliamente investigados para aplicaciones biomédicas, teniendo especial relevancia cuando se encuentran en forma de micro- y nano-partículas. Últimamente se ha ampliado su campo de aplicación al ser conjugados con péptidos y ácidos nucleicos, por lo tanto, el interés en el estudio de este tipo de materiales, así como también en la formulación de nanoestructuras funcionalizadas como materiales, dispositivos y vehículos de transporte de agentes terapéuticos ha aumentado. Las recientes investigaciones en nanosistemas se inspiran en fenómenos naturales que estimulan la integración de señales moleculares y la mimetización de procesos a nivel celular, de tejidos y órganos. Tecnológicamente, la capacidad de obtener nanoestructuras esféricas mediante la combinación de materiales que presenten propiedades distintas a las que ningún otro material individual posee por sí solo, es lo que hace que las nanocápsulas sean particularmente atractivas. Las potenciales ventajas de los sistemas de nanopartículas de tipo polimérico se destacan a lo largo de cada parte de este artículo de revisión. El presente artículo aborda los aspectos más relevantes sobre la estructura, composición y algunos métodos de elaboración de los sistemas nanoparticulados. Además, expone algunos de los trabajos más recientes, centrados en sistemas de nanopartículas basados en polímeros dirigidos a la administración de agentes, publicados en artículos especializados de investigación y revisiones durante los últimos años.

Polymeric materials have been extensively investigated for biomedical applications including micro- and nanoparticles. Modern advances have broadened horizons for application with peptides and nucleic acids. Therefore, interests increased in the formulation of materials, devices and vehicles for transporting therapeutic agents in functionalized nanostructures. Recent nano-systems are inspired by natural phenomena that stimulate the integration of molecular signals and the mimicking of natural cellular processes, at tissue and organ levels. Technologically, the ability to obtain spherical nanostructures, which combine different properties, that no other single material possesses on its own, makes nanocapsules particularly attractive. Potential advantages over polymer nanoparticulate systems are highlighted throughout each part of this review article. Here, we address the most relevant aspects of structure, composition and methods of formulation of nanoparticulate systems. In addition, we outline some of the more recent works focusing on nanosized preparations, based on agent-directed polymers, found in specialized research articles that have emerged in the recent years.

Absorption enhancing effects and safety of PAMAM dendrimers on liquiritin / 中国中药杂志

PAMAM dendrimer is one of the most widely studied dendrimers in recent years, which has a large number of functional groups on the surface and cavities inside, specific three-dimensional structure and good biocompatibility, permeability and stability. It has been widely applied in drug and gene carrier fields and may become a new absorption enhancer. In order to study the absorption enhancing effects of PAMAM dendrimers, liquiritin was selected as the model drug, with the protection of spleen and liver, detoxification and other functions, but it had not been widely used in clinical application because of its difficult absorption, first pass effect, and low bioavailability. This topic was based on the two main determinants (solubility and permeability) of intestinal absorption in the body, researched the physicochemical properties of liquiritin, analyzed the transport volume of liquiritin with or without PAMAM dendrimers by using Caco-2 cell model, and analyzed the cytotoxicity of PAMAM dendrimers on Caco-2 cells by MTT experiments. These results showed that 0.1% of the G4 generation PAG can promote the absorption of liquiritin safely and effectively, and it was suitable for further development into a new type of pharmaceutical excipients.

Cytotoxicity of non-viral gene vector polyamide amine dendrimers-hyaluronic acid polymer / 中国药理学与毒理学杂志

OBJECTIVE To study the cytotoxicity of polyamide amine dendrimers (PAMAM)-hyaluronic acid(HA)as a non-viral gene delivery vector in vitro. METHODS PAMAM-HA was synthesized by our laboratory. Cytotoxicities of various polymers on HeLa cells,Bel-7402 cells and HepG2 cells were evaluated by MTT assay. Apoptotic rates were determined by flow cytometry. RESULTS The cytotoxicity of PAMAM-HA polymer increased with the concentration of polymer(50-800 mg · L-1),the time of action(24-72 h), the number of generations of PAMAM(G4,G5) and decrease in the molecular mass(3850,17 200)and the graft density(5%-25%)of HA. After incubation with PAMAM G4-HA3850-5%or PAMAM G5-HA3850-5%for 24 h,the apoptotic rate of hepatoma cells—Bel-7402 cells was 4.5%and 9.9%,respectively. After incubation with complexes of PAMAM G4-HA3850-5%/DNA or PAMAM G5-HA3850-5%/DNA for 24 h,the viability of HeLa cells was more than 80%,which was lower than that of PAMAM G4/DNA和PAMAM G5/DNA. CONCLUSION Cytotoxicity of PAMAM modified by HA of different grafting density and quantity can be reduced ,suggesting the PAMAM is a promising non-viral gene vector.

Inhibitory effect of PAMAM/sh-miR-34a nanocomplexes on malignant melanoma cells / 第二军医大学学报

Objective To use polyamidoamine dendrimers (PAMAM) loaded with sh miR 34a for constructing PAMAM/ sh-miR-34a nanocomplexes and to observe its inhibitory effect on the proliferation, invasion and metastasis of malignant melanoma A375 cells. Methods Particle size analyzer was used to investigate the potential and size of the constructed PAMAM/sh-miR-34a nanocomplex, and sh-miR-34a enrichment capability was determined by gel electrophoresis assay. The intracellular uptake of PAMAM/sh-miR-34a by A375 cells was investigated using sh-miR-34a labeled by rhodamine. CCK8 method was used to determine the inhibitory effect of the nanocomplex against A375 cell proliferation. Transwell assay was used to determine the inhibition effect of nanocomplex against A375 cell migration and invasion. Western blotting analysis was used to examine the inhibitory effect of PAMAM/sh-miR-34a on the protein expression of pAkt, pRb, and pERKl/2 in A375 cells. Results PAMAM loaded with sh-miR-34a could form stable nanocomplexes. The intracellular uptake of PAMAM/sh-miR-34a by A375 cells was the highest when N/P = 20 (P<0. 05). PAMAM effectively mediated sh-miR-34a entry into A375 cells, inhibiting the cell proliferation- invasion and metastasis and blocking the protein expression of pAkt, pRb. and pERKl/2 in A375 cells. Conclusion PAMAM can enwrap sh-miR-34a and inhibit malignant melanoma A375 cells

A Hydrogen Peroxide Sensor Based on Palladium Nanoparticles Loading to Poly(amidoamine) Dendrimers Functionalized Carbon Nanotubes / 分析化学

The fourth generation poly( amidoamine) dendrimers ( G4. 0 PAMAM) functionalized multiwalled carbon nanotube ( G4 . 0-MWCNTs ) was prepared by amidation between carboxylated multiwalled carbon nanotube (MWCNTs) and G4. 0 PAMAM. Then a novel hydrogen peroxide (H2O2) sensor was fabricated by electrodepositing Pd nanoparticles (NPs) on a glassy carbon electrode (GCE) modified with G4. 0-MWCNTs composites. The modified electrode was characterized by field emission scanning electron microscopy ( FESEM) , cyclic voltammetry ( CV) and electrochemical impedance spectroscopy ( EIS) . A large amounts of highly dispersion PdNPs could be well loaded on the surface of the G4. 0-MWCNTs, and the modified electrode exhibited excellent electrocatalytic activity towards the reduction of H2 O2 . Under the optimized conditions, the reduction peak currents of H2 O2 were linear to their concentrations in the range from 1. 0 × 10-9 mol/L to 1. 0×10-3 mol/L and the limit of detection of 2. 3×10-8 mol/L was obtained. The recovery of standard addition for human serum samples was 96 . 7%-103 . 1%.

Dendrimers: a Review on Synthetic Approaches.

This review article is focused on different synthetic strategies used in dendrimer synthesis at commercial and laboratory scale. These synthetic strategies includes their own advantages and disadvantages. This review will cover divergent (from core to surface) and convergent (from surface to core) approaches used in dendrimer synthesis and the problems associated with these synthetic strategies. This article also covers the important applications of dendrimers in the field of pharmaceutical sciences. This data of review is collected from various articles, research papers and patents available on dendrimers.

Dendrimers and their Applications as Novel Drug Delivery Carriers.

Dendrimers are novel synthetic polymeric systems having improved physical and chemical properties due to their unique three dimensional architecture. Dendrimers have a well defined size, shape, molecular weight and monodispersity. These are compatible with drug moieties as well as bioactive molecules like DNA, heparin and other polyanions. The nanoscopic size and recognition abilities make dendrimers as ideal building blocks for self-assembly and self-organization systems. The cavities inside the dendritic structure can be modified to incorporate hydrophobic and hydrophilic drugs. The terminal groups are modified to attach antibodies and bioactive substances for targeting purpose along with providing miscibility, reactivity and solubility. Currently, dendrimers are of great interest for delivering drug molecules via different routes as a nanocarrier. Toxicity problems associated with cationic dendrimers are overcome by PEGylation, which neutralizes the charge on them. Dendrimers possess suitable properties to establish itself as a potential carrier for delivery of therapeutic agents irrespective of certain synthetic and regulatory constraints. This review contains various structural aspects and properties of dendrimers along with their pharmaceutical application as a potential novel drug delivery carrier.

Biological properties of water-soluble phosphorhydrazone dendrimers

Dendrimers are hyperbranched and perfectly defined macromolecules, constituted of branches emanating from a central core in an iterative fashion. Phosphorhydrazone dendrimers constitute a special family of dendrimers, possessing one phosphorus atom at each branching point. The internal structure of these dendrimers is hydrophobic, but hydrophilic terminal groups can induce the solubility of the whole structure in water. Indeed, the properties of these compounds are mainly driven by the type of terminal groups their bear; this is especially true for the biological properties. For instance, positively charged terminal groups are efficient for transfection experiments, as drug carriers, as anti-prion agents, and as inhibitor of the aggregation of Alzheimer's peptides, whereas negatively charged dendrimers have anti-HIV properties and can influence the human immune system, leading to anti-inflammatory properties usable against rheumatoid arthritis. This review will give the most representative examples of the biological properties of water-soluble phosphorhydrazone dendrimers, organized depending on the type of terminal groups they bear.

Dendrímeros são macromoléculas extremamente ramificadas e perfeitamente definidas constituídas de ramificações que partem de um foco central de uma forma iterativa. Dendrímeros de fosforidrazona constituem uma família especial de dendrímeros, que possuem um átomo de fósforo em cada ponto da ramificação. A estrutura interna destes dendrímeros é hidrofóbica, mas grupos hidrofílicos terminais podem induzir a solubilidade em água de toda estrutura. De fato, as propriedades destes compostos são principalmente orientadas pelos grupos terminais que apresentam, especialmente para as propriedades biológicas. Por exemplo, grupos terminais carregados positivamente são eficientes para experimentos de transfecção, como transportadores de fármacos, agentes antipríons e como inibidores da agregação de peptídeos do Alzheimer, enquanto que dendrímeros carregados negativamente têm propriedades anti-HIV e podem influenciar o sistema imune humano, levando propriedades antiinflamatórias úteis contra artrite reumatoide. Essa revisão dará os exemplos mais representativos das propriedades biológicas de dendrímeros de fosforidrazona solúveis em água, organizados de acordo com os grupos terminais que possuem.

Synthesis and MALDI-ToF characterization of dendronized poly(ethylene glycol)s

Well-defined hybrids of linear poly(ethylene glycol)s (PEGs) and dendritic polyesters were prepared via the dendronization of the alcohol end groups of the mono and difunctional linear PEGs. Though useful for rudimentary product characterization, GPC and NMR could not verify the overall structural purity of these linear-dendritic hybrids. On the other hand, the detailed data provided by MALDI-ToF mass spectrometry enabled confirmation of the high structural purity of the dendronized PEGs at each step of the dendronization procedure. The well-defined number of functionalities on these dendronized PEGs, renders them particularly useful for research in the biomedical sphere where functionality and purity are of the utmost importance. The MALDI-ToF mass spectrometric approach described herein represents a valuable technique for detailed monitoring of these dendronization reactions, as well as a variety of other polymer end group modifications.

Híbridos bem definidos de poli(etilenoglicol) lineares (PEGs) e poliésteres dendriméricos foram preparados via "dendronização" de álcool e grupos de PEGs lineares mono e bifuncionais. Embora úteis para a caracterização rudimentar de produtos, Cromatografia por Permeação em Gel e RMN podem não demonstrar a pureza estrutural global desses híbridos lineares dendríticos. Por outro lado, informações detalhadas provenientes de espectrometria de massas MALDI-ToF permitiram a confirmação de elevada pureza estrutural de PEGs "dendronizados" em cada passo do processo de "dendronização". O número de funcionalidades bem definidas destes PEGs "dendronizados", torna-os particularmente úteis para pesquisa na área biomédica, na qual funcionalidade e pureza são de grande importância. A abordagem de espectrometria de massas MALDI-ToF descrita aqui representa uma técnica valiosa para o monitoramento detalhado destas reações de "dendronização", bem como diversas modificações de outros polímeros e grupos.

Dendrimers as anti-inflammatory agents

Dendrimers constitute an intriguing class of macromolecules which find applications in a variety of areas including biology. These hyperbranched macromolecules with tailored backbone and surface groups have been extensively investigated as nanocarriers for gene and drug delivery, by molecular encapsulation or covalent conjugation. Dendrimers have provided an excellent platform to develop multivalent and multifunctional nanoconjugates incorporating a variety of functional groups including drugs which are known to be anti-inflammatory agents. Recently, dendrimers have been shown to possess anti-inflammatory properties themselves. This unexpected and intriguing discovery has provided an additional impetus in designing novel active pharmaceutical agents. In this review, we highlight some of the recent developments in the field of dendrimers as nanoscale anti-inflammatory agents.

Dendrímeros constituem uma classe intrigante de macromoléculas que apresentam aplicações em diversas áreas incluindo biologia. Essas macromoléculas extremamente ramificadas com esqueleto planejado e grupos de superfície foram extensivamente investigadas como nanotransportadores de genes e de fármacos, por encapsulamento molecular ou conjugação covalente. Dendrímeros têm proporcionado uma plataforma excelente de desenvolvimento nanoconjugados multivalentes e multifuncionais incorporando uma variedade de grupos funcionais, incluindo fármacos que são conhecidos por atuarem agentes antiinflamatórios. Recentemente, os dendrímeros mostraram propriedades antiinflamatórias. Esta inesperada e intrigante descoberta tem proporcionado um impulso adicional no planejamento de novos agente farmacêuticos ativos. Nesta revisão, nós destacamos alguns dos desenvolvimentos recentes no campo dos dendrímeros como agentes antiinflamatórios em nanoescala.

Cancer therapeutics- opportunities, challenges and advances in drug delivery.

This review highlights the characteristics of the cancer that provide opportunities for drug delivery carriers to target cancer. These opportunities include EPR effect, high interstitial pressure of tumour, low pH of endosomes of tumor cells, overexpressed receptors, angiogenesis etc. Chemotherapy is one of the most important treatments currently available among the various approaches. The present status of chemotherapy is far from being satisfactory. Its efficacy is limited and patients have to suffer from serious side effects, some of which are life-threatening. The newer approaches to cancer treatment not only supplement the conventional chemotherapy but also aim to prevent damage to the normal tissues and overcome drug resistance. The innovative approaches of cancer treatment require new concepts of drug delivery in cancer. This concept requires the unique surface morphology which ultimately determines the fate of new drug delivery systems. The Innovative methods must also shoot out the associated problems of cancer like multidrug resistance by tumor cells. Progress in developing various controlled and targeted drug delivery systems has reviewed here with an emphasis on dendrimeric drug delivery system. Dendrimeric system appears to be promising in cancer chemotherapy especially via ligand/receptor mediated endocytosis as it posses numerous properties (especially surface property) to target cancer.

Progress in research of polyamidoamine dendrimers as gene carriers / 国际生物医学工程杂志

Polyamidoamine (PAMAM) dendrimers is considered a better genetic carrier for its ability to form with DNA a nano-sized polyelectrolyte complex of high stability and dissolubility. The mechanism of PAMAMmediated gene endocytosis has been fairly clear and the researches in vitro have confirmed that PAMAM had high transfection efficiency and low cytotoxicity. The researches in vivo have further confirmed that PAMAM had a potential application foreground in the field of gene therapy including in the prevention and treatment of ewing's sarcoma and pulmonary fibrosis, in heart transplantation, and in the preparation of falciparum malaria vaccine.