Preparation of size tunable amphiphilic poly(amino acid) nanoparticles

Synthesis and characterization of novel poly cysteine methacrylate nanoparticles and their morphology and size studies

Polymer nanoparticles (PNPs) have significantly advanced the field of biomedicine, showcasing the remarkable potential for precise drug delivery, administration of nutraceuticals, diagnostics/imaging applications, and the fabrication of biocompatible materials, among other uses. Despite these promising developments, the invention faces notable challenges related to biodegradability, bioactivity, target-site specificity, particle size, carrier efficiency, and controlled release. Addressing these concerns is essential for optimizing the functionality and impact of PNPs in biomedical applications. Here, new poly cysteine methacrylate nanoparticles (PCMANPs), ca. (200 nm) in size have been synthesized from the cysteine methacrylate (CysMA) monomer using different strategies, including emulsion and inverse emulsion polymerization techniques. The monomer was synthesized using the Michael addition reaction, involving the addition of 3-(acryloyloxy)-2-hydroxypropyl methacrylate to the sulfhydryl group (-SH) of the cysteine (Cys) active site, with the aid of dimethyl phenyl phosphine (DMPP) as a nucleophilic agent as previously reported. To enhance nano-polymerization, a thorough exploration of various initiators, including ammonium persulfate (APS) and 4,4'-azobis (4-cyanovaleric acid) (ACVA), alongside surfactants, such as polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), and sodium dodecyl sulfate (SDS), was conducted. Additionally, critical parameters, such as reaction time, temperature, and solvents, were systematically investigated due to their substantial influence on the shape, size, stability, and morphology of the synthesized polymer nanoparticles. This comprehensive approach aims to optimize the synthesis process, ensuring precise control over the key characteristics of the resulting nanoparticles for enhanced performance in diverse applications. Various characterization techniques, including field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), zeta potential, and zeta sizer dynamic light scattering (DLS) analysis, were utilized to investigate purity, morphology, and particle size of the PNPs. As a result, a spherical, monodispersed (homogenized), and stable PCMANP with defined size and morphology was achieved. This may exhibit a remarkable achievement in the future of drug delivery systems and therapeutic index.

Preparation, Characterization and Drug Delivery Research of γ-Polyglutamic Acid Nanoparticles: A Review

γ-Polyglutamic acid is a kind of biomaterial and environmentally friendly polymer material with the characteristics of water solubility and good biocompatibility. It has a wide range of applications in medicine, food, cosmetics and other fields. This article reviews the preparation, characterization and medical applications of γ-polyglutamic acid nanoparticles. Nanoparticles prepared by using γ- polyglutamic acid not only had the traditional advantages of enhancing drug stability and slow-release effect, but also were simple to prepare without any biological toxicity. The current methods of nanoparticle preparation mainly include the ion gel method and solvent exchange method, which use the total electrostatic force, van der Waals force, hydrophobic interaction force and hydrogen bond force between molecules to embed materials with different characteristics. At present, there are more and more studies on the use of γ-polyglutamic acid to encapsulate drugs, and the research on the mechanism of its encapsulation and sustained release has gradually matured. The development and application of polyglutamic acid nanoparticles have broad prospects.

Poly-γ-glutamic acid nanoparticles as adjuvant and antigen carrier system for cancer vaccination

Vaccination is an innovative strategy for cancer treatment by leveraging various components of the patients' immunity to boost an anti-tumor immune response. Rationally designed nanoparticles are well suited to maximize cancer vaccination by the inclusion of immune stimulatory adjuvants. Also, nanoparticles might control the pharmacokinetics and destination of the immune potentiating compounds. Poly-γ-glutamic acid (γ-PGA) based nanoparticles (NPs), which have a natural origin, can be easily taken up by dendritic cells (DCs), which leads to the secretion of cytokines which ameliorates the stimulation capacity of T cells. The intrinsic adjuvant properties and antigen carrier properties of γ-PGA NPs have been the focus of recent investigations as they can modulate the tumor microenvironment, can contribute to systemic anti-tumor immunity and subsequently inhibit tumor growth. This review provides a comprehensive overview on the potential of γ-PGA NPs as antigen carriers and/or adjuvants for anti-cancer vaccination.

Nanoparticle-encapsulated antioxidant improves placental mitochondrial function in a sexually dimorphic manner in a rat model of prenatal hypoxia

Pregnancy complications associated with prenatal hypoxia lead to increased placental oxidative stress. Previous studies suggest that prenatal hypoxia can reduce mitochondrial respiratory capacity and mitochondrial fusion, which could lead to placental dysfunction and impaired fetal development. We developed a placenta-targeted treatment strategy using a mitochondrial antioxidant, MitoQ, encapsulated into nanoparticles (nMitoQ) to reduce placental oxidative stress and (indirectly) improve fetal outcomes. We hypothesized that, in a rat model of prenatal hypoxia, nMitoQ improves placental mitochondrial function and promotes mitochondrial fusion in both male and female placentae. Pregnant rats were treated with saline or nMitoQ on gestational day (GD) 15 and exposed to normoxia (21% O₂ ) or hypoxia (11% O₂ ) from GD15-21. On GD21, male and female placental labyrinth zones were collected for mitochondrial respirometry assessments, mitochondrial content, and markers of mitochondrial biogenesis, fusion and fission. Prenatal hypoxia reduced complex IV activity and fusion in male placentae, while nMitoQ improved complex IV activity in hypoxic male placentae. In female placentae, prenatal hypoxia decreased respiration through the S-pathway (complex II) and increased N-pathway (complex I) respiration, while nMitoQ increased fusion in hypoxic female placentae. No changes in mitochondrial content, biogenesis or fission were found. In conclusion, nMitoQ improved placental mitochondrial function in male and female placentae from fetuses exposed to prenatal hypoxia, which may contribute to improved placental function. However, the mechanisms (ie, changes in mitochondrial respiratory capacity and mitochondrial fusion) were distinct between the sexes. Treatment strategies targeted against placental oxidative stress could improve placental mitochondrial function in complicated pregnancies.

Maternal antioxidant treatment prevents the adverse effects of prenatal stress on the offspring's brain and behavior

Maternal exposure to stress during pregnancy is associated with an increased risk of psychiatric disorders in the offspring in later life. The mechanisms through which the effects of maternal stress are transmitted to the fetus are unclear, however the placenta, as the interface between mother and fetus, is likely to play a key role. Using a rat model, we investigated a role for placental oxidative stress in conveying the effects of maternal social stress to the fetus and the potential for treatment using a nanoparticle-bound antioxidant to prevent adverse outcomes in the offspring.

Maternal psychosocial stress increased circulating corticosterone in the mother, but not in the fetuses. Maternal stress also induced oxidative stress in the placenta, but not in the fetal brain. Blocking oxidative stress using an antioxidant prevented the prenatal stress-induced anxiety phenotype in the male offspring, and prevented sex-specific neurobiological changes, specifically a reduction in dendrite lengths in the hippocampus, as well as reductions in the number of parvalbumin-positive neurons and GABA receptor subunits in the hippocampus and basolateral amygdala of the male offspring. Importantly, many of these effects were mimicked in neuronal cultures by application of placental-conditioned medium or fetal plasma from stressed pregnancies, indicating molecules released from the placenta may mediate the effects of prenatal stress on the fetal brain. Indeed, both placenta-conditioned medium and fetal plasma contained differentially abundant microRNAs following maternal stress, and their predicted targets were enriched for genes relevant to nervous system development and psychiatric disorders.

The results highlight placental oxidative stress as a key mediator in transmitting the maternal social stress effects on the offspring's brain and behavior, and offer a potential intervention to prevent stress-induced fetal programming of affective disorders.

•

Social stress in pregnancy induces oxidative stress but is prevented by antioxidant.

•

Prenatal stress induces behavioural, neuroanatomical and neurochemical changes.

•

Maternal antioxidant treatment prevents stress-induced effects in the offspring.

•

Maternal stress alters the balance of microRNAs secreted from the placenta.

•

Placental oxidative stress mediates maternal social stress effects on the offspring.

Placenta-targeted treatment strategies: An opportunity to impact fetal development and improve offspring health later in life

The Developmental Origins of Health and Disease (DOHaD) theory states that a sub-optimal prenatal and early postnatal environment during development leads to an increased risk of long-term development of adult chronic diseases. Developmental programming of disease has the potential to greatly impact the health of our population. Therefore, research has focused on the development of primary treatment strategies and/or therapeutic interventions for individuals who are at increased risk, with the objective to reverse or prevent later life onset of chronic disease in the offspring born from complicated pregnancies. Many studies have focused on systemic treatments and/or interventions in complicated pregnancies to improve offspring outcomes. However, there are limitations to systemic maternal/prenatal treatments, as most of the treatments are able to cross the placenta and have potential adverse off-target effects on the developing fetus. The placenta serves as the primary interface between mother and fetus, and placental dysfunction in complicated pregnancies has been associated with impaired fetal development and negative impact on offspring health. Therefore, recent research has focused on treatment strategies that specifically target the placenta to improve placental function and prevent passage of prenatal therapeutics and/or treatments into the fetal circulation, thus avoiding any potential adverse off-target effects on the fetus. This article reviews the currently available knowledge on treatment strategies and/or therapeutics that specifically target the placenta with the goal of improving pregnancy outcomes with a focus on long-term health of the offspring born of complicated pregnancies.

Sex-Specific Effects of Nanoparticle-Encapsulated MitoQ (nMitoQ) Delivery to the Placenta in a Rat Model of Fetal Hypoxia

Pregnancy complications associated with chronic fetal hypoxia have been linked to the development of adult cardiovascular disease in the offspring. Prenatal hypoxia has been shown to increase placental oxidative stress and impair placental function in a sex-specific manner, thereby affecting fetal development. As oxidative stress is central to placental dysfunction, we developed a placenta-targeted treatment strategy using the antioxidant MitoQ encapsulated into nanoparticles (nMitoQ) to reduce placental oxidative/nitrosative stress and improve placental function without direct drug exposure to the fetus in order to avoid off-target effects during development. We hypothesized that, in a rat model of prenatal hypoxia, nMitoQ prevents hypoxia-induced placental oxidative/nitrosative stress, promotes angiogenesis, improves placental morphology, and ultimately improves fetal oxygenation. Additionally, we assessed whether there were sex differences in the effectiveness of nMitoQ treatment. Pregnant rats were intravenously injected with saline or nMitoQ (100 μl of 125 μM) on gestational day (GD) 15 and exposed to either normoxia (21% O2) or hypoxia (11% O2) from GD15 to 21. On GD21, placentae from both sexes were collected for detection of superoxide, nitrotyrosine, nitric oxide, CD31 (endothelial cell marker), and fetal blood spaces, Vegfa and Igf2 mRNA expression in the placental labyrinth zone. Prenatal hypoxia decreased male fetal weight, which was not changed by nMitoQ treatment; however, placental efficiency (fetal/placental weight ratio) decreased by hypoxia and was increased by nMitoQ in both males and females. nMitoQ treatment reduced the prenatal hypoxia-induced increase in placental superoxide levels in both male and female placentae but improved oxygenation in only female placentae. Nitrotyrosine levels were increased in hypoxic female placentae and were reduced by nMitoQ. Prenatal hypoxia reduced placental Vegfa and Igf2 expression in both sexes, while nMitoQ increased Vegfa and Igf2 expression only in hypoxic female placentae. In summary, our study suggests that nMitoQ treatment could be pursued as a potential preventative strategy against placental oxidative stress and programming of adult cardiovascular disease in offspring exposed to hypoxia in utero. However, sex differences need to be taken into account when developing therapeutic strategies to improve fetal development in complicated pregnancies, as nMitoQ treatment was more effective in placentae from females than males.

DNA damage signalling from the placenta to foetal blood as a potential mechanism for childhood leukaemia initiation

For many diseases with a foetal origin, the cause for the disease initiation remains unknown. Common childhood acute leukaemia is thought to be caused by two hits, the first in utero and the second in childhood in response to infection. The mechanism for the initial DNA damaging event are unknown. Here we have used in vitro, ex vivo and in vivo models to show that a placental barrier will respond to agents that are suspected of initiating childhood leukaemia by releasing factors that cause DNA damage in cord blood and bone marrow cells, including stem cells. We show that DNA damage caused by in utero exposure can reappear postnatally after an immune challenge. Furthermore, both foetal and postnatal DNA damage are prevented by prenatal exposure of the placenta to a mitochondrially-targeted antioxidant. We conclude that the placenta might contribute to the first hit towards leukaemia initiation by bystander-like signalling to foetal haematopoietic cells.

Preeclamptic placentae release factors that damage neurons: implications for foetal programming of disease

Prenatal development is a critical period for programming of neurological disease. Preeclampsia, a pregnancy complication involving oxidative stress in the placenta, has been associated with long-term health implications for the child, including an increased risk of developing schizophrenia and autism spectrum disorders in later life. To investigate if molecules released by the placenta may be important mediators in foetal programming of the brain, we analysed if placental tissue delivered from patients with preeclampsia secreted molecules that could affect cortical cells in culture. Application of culture medium conditioned by preeclamptic placentae to mixed cortical cultures caused changes in neurons and astrocytes that were related to key changes observed in brains of patients with schizophrenia and autism, including effects on dendrite lengths, astrocyte number as well as on levels of glutamate and γ-aminobutyric acid receptors. Treatment of the placental explants with an antioxidant prevented neuronal abnormalities. Furthermore, we identified that bidirectional communication between neurons and astrocytes, potentially via glutamate, is required to produce the effects of preeclamptic placenta medium on cortical cells. Analysis of possible signalling molecules in the placenta-conditioned medium showed that the secretion profile of extracellular microRNAs, small post-transcriptional regulators, was altered in preeclampsia and partially rescued by antioxidant treatment of the placental explants. Predicted targets of these differentially abundant microRNAs were linked to neurodevelopment and the placenta. The present study provides further evidence that the diseased placenta may release factors that damage cortical cells and suggests the possibility of targeted antioxidant treatment of the placenta to prevent neurodevelopmental disorders.

Preparation of PGA-PAE-Micelles for Enhanced Antitumor Efficacy of Cisplatin

Poly-γ-l-glutamic acid (PGA) is an outstanding drug carrier candidate owning to its excellent biodegradability and biocompatibility. The PGA carrier may shield toxic drugs from the body and enable the delivery of poorly soluble or unstable drugs and thereby minimize the side effects and improve drug efficacy. However, the limitation of PGA as a drug carrier is low drug loading efficiency (DLE), which is usually below 30%. In this study, we reported a chemical modification method using l-phenylalanine ethyl ester (PAE). PGA-PAE construct was amphiphilic, which could form micelles in aqueous solution. Cisplatin (CDDP), a commonly used chemotherapy drug whose side effect is well-known, was used as a model molecule to test the drug-loading efficiency of PGA-PAE. In this paper, two sizes of CDDP-loaded PGA-PAE micelles (M(Pt)-1 and M(Pt)-2) were prepared, the average diameter of M(Pt)-1 was 106 ± 6 nm and M(Pt)-2 was 210 ± 9 nm. The DLE of M(Pt)-1 and M(Pt)-2 was 52.8 ± 2.2 and 55.8 ± 1.2%, respectively. Both exhibited excellent biocompatibility, stability, and drug-retaining capability in physiological condition. The in vitro accumulative drug-releasing profile, IC₅₀ for different tumor cell lines HeLa, A549, and HCCC9810, and in vivo pharmacokinetics were similar between these two micelles; however, M(Pt)-1 showed higher tumor tissue retention and longer efficient cancer cell internalization time (up to 20 d). Our results suggested PGA-PAE micelle carriers reduced the toxicity of CDDP and its size at around 100 nm was the better for CDDP high-efficacy.

Development of analytical methods for evaluating the quality of dissociated and associated amphiphilic poly(γ-glutamic acid) nanoparticles

A quantitative method of analyzing nanoparticles (NPs) for drug delivery is urgently required by researchers and industry. Therefore, we developed new quantitative analytical methods for biodegradable and amphiphilic NPs consisting of polymeric γ-PGA-Phe [phenylalanine attached to poly(γ-glutamic acid)] molecules. These γ-PGA-Phe NPs were completely dissociated into separate γ-PGA-Phe molecules by adding sodium dodecyl sulfate (SDS). The dissociated NPs were chromatographically separated to analyze parameters such as the γ-PGA-Phe content in the NPs, the impurities present [using reverse-phase (RP) HPLC with an ultraviolet (UV) detector], and the absolute MW [using size-exclusion chromatography (SEC) with refractive index detection (RI) and multiangle light scattering (MALS) detection, i.e., SEC-RI/MALS]. The chromatographic patterns of the NPs were equivalent to those of the component polymer (γ-PGA-Phe), and excellent chromatographic separation for the quantitative evaluation of NPs was achieved. To the best of our knowledge, this is the first report of the quantitative evaluation of NPs in the field of NP-based delivery systems. Furthermore, these methods were applied to optimize and evaluate the NP manufacturing process. The results showed that impurities were effectively removed from the γ-PGA-Phe during the manufacturing process, so the purity of the final γ-PGA-Phe NPs was enhanced. In addition, the appearance, clarity of solution, particle size, zeta potential, particle matter, osmolarity, and pH of the product were evaluated to ensure that the NPs were of the required quality. Our approach should prove useful for product and process characterization and quality control in the manufacture of NPs. γ-PGA-Phe NPs are known to be a powerful vaccine adjuvant, so they are expected to undergo clinical development into a practical drug-delivery system. The analytical methods established in this paper should facilitate the reliable and practical quality testing of NP products, thus aiding the clinical development of γ-PGA-Phe-based drug-delivery systems. Moreover, since these analytical methods employ commonly used reagents and chromatographic systems, the methods are expected to be applicable to other NP-based drug-delivery products too. Graphical abstract NPs were completely dissociated into separate γ-PGA-Phe polymeric molecules, which yielded a similar chromatogram to that seen for the NPs.

Maternal treatment with a placental-targeted antioxidant (MitoQ) impacts offspring cardiovascular function in a rat model of prenatal hypoxia

Intrauterine growth restriction, a common consequence of prenatal hypoxia, is a leading cause of fetal morbidity and mortality with a significant impact on population health. Hypoxia may increase placental oxidative stress and lead to an abnormal release of placental-derived factors, which are emerging as potential contributors to developmental programming. Nanoparticle-linked drugs are emerging as a novel method to deliver therapeutics targeted to the placenta and avoid risking direct exposure to the fetus. We hypothesize that placental treatment with antioxidant MitoQ loaded onto nanoparticles (nMitoQ) will prevent the development of cardiovascular disease in offspring exposed to prenatal hypoxia. Pregnant rats were intravenously injected with saline or nMitoQ (125 μM) on gestational day (GD) 15 and exposed to either normoxia (21% O₂) or hypoxia (11% O₂) from GD15-21 (term: 22 days). In one set of animals, rats were euthanized on GD 21 to assess fetal body weight, placental weight and placental oxidative stress. In another set of animals, dams were allowed to give birth under normal atmospheric conditions (term: GD 22) and male and female offspring were assessed at 7 and 13 months of age for in vivo cardiac function (echocardiography) and vascular function (wire myography, mesenteric artery). Hypoxia increased oxidative stress in placentas of male and female fetuses, which was prevented by nMitoQ. 7-month-old male and female offspring exposed to prenatal hypoxia demonstrated cardiac diastolic dysfunction, of which nMitoQ improved only in 7-month-old female offspring. Vascular sensitivity to methacholine was reduced in 13-month-old female offspring exposed to prenatal hypoxia, while nMitoQ treatment improved vasorelaxation in both control and hypoxia exposed female offspring. Male 13-month-old offspring exposed to hypoxia showed an age-related decrease in vascular sensitivity to phenylephrine, which was prevented by nMitoQ. In summary, placental-targeted MitoQ treatment in utero has beneficial sex- and age-dependent effects on adult offspring cardiovascular function.

Treating the placenta to prevent adverse effects of gestational hypoxia on fetal brain development

Some neuropsychiatric disease, including schizophrenia, may originate during prenatal development, following periods of gestational hypoxia and placental oxidative stress. Here we investigated if gestational hypoxia promotes damaging secretions from the placenta that affect fetal development and whether a mitochondria-targeted antioxidant MitoQ might prevent this. Gestational hypoxia caused low birth-weight and changes in young adult offspring brain, mimicking those in human neuropsychiatric disease. Exposure of cultured neurons to fetal plasma or to secretions from the placenta or from model trophoblast barriers that had been exposed to altered oxygenation caused similar morphological changes. The secretions and plasma contained altered microRNAs whose targets were linked with changes in gene expression in the fetal brain and with human schizophrenia loci. Molecular and morphological changes in vivo and in vitro were prevented by a single dose of MitoQ bound to nanoparticles, which were shown to localise and prevent oxidative stress in the placenta but not in the fetus. We suggest the possibility of developing preventative treatments that target the placenta and not the fetus to reduce risk of psychiatric disease in later life.

Peptide grafted and self-assembled poly(γ-glutamic acid)-phenylalanine nanoparticles targeting camptothecin to glioma

Aim: To synthesize cRGDfK peptide conjugated poly(γ-glutamic acid)-phenylalanine nanoparticles to improve the therapeutic efficacy of camptothecin (CPT) against glioblastoma multiforme. Methods: Peptide-conjugated, drug-loaded nanoparticles (cRGDfK-conjugated camptothecin-loaded PGA–PA nanoparticles [RCPN]) were prepared and physico-chemically characterized using different techniques. Nanoparticles were evaluated for in vitro anticancer activity, cellular uptake, induction of apoptosis and wound healing cell migration against U87MG human glioblastoma cells. Results: RCPN, with a particle size of <100 nm and 65% CPT encapsulation efficiency, exhibited a dose- and time-dependent cytotoxicity to glioblastoma cells. Compared with native CPT or unconjugated nanoparticles, RCPN induced apoptosis, increased reactive oxygen species generation and inhibited U87MG cell migration. Conclusion: cRGDfK-mediated and amphiphilic copolymer-based nanomedicines represent a new approach for improved delivery of anticancer drugs to and treatment of glioblastoma multiforme.

Bacterial-Derived Polymer Poly-y-Glutamic Acid (y-PGA)-Based Micro/Nanoparticles as a Delivery System for Antimicrobials and Other Biomedical Applications

In the past decade, poly-γ-glutamic acid (γ-PGA)-based micro/nanoparticles have garnered remarkable attention as antimicrobial agents and for drug delivery, owing to their controlled and sustained-release properties, low toxicity, as well as biocompatibility with tissue and cells. γ-PGA is a naturally occurring biopolymer produced by several gram-positive bacteria that, due to its biodegradable, non-toxic and non-immunogenic properties, has been used successfully in the medical, food and wastewater industries. Moreover, its carboxylic group on the side chains can offer an attachment point to conjugate antimicrobial and various therapeutic agents, or to chemically modify the solubility of the biopolymer. The unique characteristics of γ-PGA have a promising future for medical and pharmaceutical applications. In the present review, the structure, properties and micro/nanoparticle preparation methods of γ-PGA and its derivatives are covered. Also, we have highlighted the impact of micro/nanoencapsulation or immobilisation of antimicrobial agents and various disease-related drugs on biodegradable γ-PGA micro/nanoparticles.

Goblet cell targeting nanoparticle containing drug-loaded micelle cores for oral delivery of insulin

Oral administration of insulin remains a challenge due to its poor enzymatic stability and inefficient permeation across epithelium. We herein developed a novel self-assembled polyelectrolyte complex nanoparticles by coating insulin-loaded dodecylamine-graft-γ-polyglutamic acid micelles with trimethyl chitosan (TMC). The TMC material was also conjugated with a goblet cell-targeting peptide to enhance the affinity of nanoparticles with epithelium. The developed nanoparticle possessed significantly enhanced colloid stability, drug protection ability and ameliorated drug release profile compared with graft copolymer micelles or ionic crosslinked TMC nanoparticles. For in vitro evaluation, Caco-2/HT29-MTX-E12 cell co-cultures, which composed of not only enterocyte-like cells but also mucus-secreting cells and secreted mucus layer, were applied to mimic the epithelium. Intracellular uptake and transcellular permeation of encapsulated drug were greatly enhanced for NPs as compared with free insulin or micelles. Goblet cell-targeting modification further increased the affinity of NPs with epithelium with changed cellular internalization mechanism. The influence of mucus on the cell uptake was also investigated. Ex vivo performed with rat mucosal tissue demonstrated that the nanoparticle could facilitate the permeation of encapsulated insulin across the intestinal epithelium. In vivo study preformed on diabetic rats showed that the orally administered nanoparticles elicited a prolonged hypoglycemic response with relative bioavailability of 7.05%.

A novel ligand conjugated nanoparticles for oral insulin delivery

In order to enhance the interaction between nanocarrier and gastrointestinal epithelial cells, we developed nanoparticles (NPs) modified with targeting ligand FQSIYPpIK (FQS), which specifically interact with integrin αvβ3 receptor expressing on the intestinal epithelium. The targeting NPs were prepared by coating the insulin-loaded poly(lactide-co-glycolide)-monomethoxy-poly(polyethylene glycol) micelle cores with FQS modified trimethyl chitosan chloride. In in vitro study, the fabricated NPs showed ameliorated drug release profile and improved enzymatic stability compared with micelles alone. In the integrin αvβ3 receptor over-expressed Caco-2 cells model, FQS modified NPs exhibited significantly accelerated intracellular uptake due to the active ligand-receptor mediation. Meanwhile, the targeting NPs also showed enhanced transport across the Caco-2 monolayer cells via both transcellular and paracellular pathways. Besides, orally administered FQS modified NPs produced a prominent hypoglycemic response and an increase of the serum insulin concentration in diabetic rats. Both in vitro and in vivo results demonstrated the FQS peptide modified NPs as promising intestinal cell-targeting nanocarriers for efficient oral delivery of insulin.

Effect of Hydrophobic Side Chains in the Induction of Immune Responses by Nanoparticle Adjuvants Consisting of Amphiphilic Poly(γ-glutamic acid)

The new generation vaccines are safe but poorly immunogenic, and thus they require the use of adjuvants. Adjuvants that can control the balance and induction level of cellular and humoral immunities are urgently required for the treatment of and/or protection from infectious diseases and cancers. However, there are no adjuvants which can achieve these requirements. In this study, amphiphilic poly(γ-glutamic acid) (γ-PGA) with various kinds of hydrophobic amino acid ethyl esters (AAE) was synthesized (γ-PGA-AAE) and used to prepare antigen-encapsulated nanoparticles (NPs). γ-PGA-graft-Leu (γ-PGA-Leu, where Leu = leucine ethyl ester), γ-PGA-graft-Phe (γ-PGA-Phe, where Phe = phenylalanine ethyl ester), and γ-PGA-graft-Trp (γ-PGA-Trp, where Trp = tryptophan ethyl ester) formed monodispersed NPs that encapsulated ovalbumin (OVA). The type and the induction level of the antigen-specific cellular and humoral immunities could be controlled by the kinds of hydrophobic segments and vaccine formulation (encapsulation or mixture) used. When OVA was encapsulated into NPs, the cellular immunity was dominantly induced, while humoral immunity was dominant when OVA was mixed with NPs. These results are a first report to demonstrate that the balance and induction level of cellular and humoral immunities could be controlled by modifying compositions of NPs and vaccine formulation. Our results suggest that γ-PGA-AAE NPs can provide safe and efficient nanoparticle-based vaccine adjuvants, and the results also provide guidelines in the rational design of amphiphilic polymers as vaccine adjuvants which can control the balance of immune responses.

Size effect of amphiphilic poly(γ-glutamic acid) nanoparticles on cellular uptake and maturation of dendritic cells in vivo

We prepared size-regulated nanoparticles (NPs) composed of amphiphilic poly(γ-glutamic acid) (γ-PGA). In this study, 40, 100 and 200 nm γ-PGA-graft-l-phenylalanine ethylester (γ-PGA-Phe) NPs were employed. The size of NPs significantly influenced the uptake and activation behaviors of antigen-presenting cells (APCs). When 40 nm γ-PGA-Phe NPs were applied to these cells in vitro, they were highly activated compared with 100 and 200 nm NPs, while cellular uptake was size dependent. The size of the γ-PGA-Phe NPs also significantly affected their migration to the lymph nodes and uptake behavior of NPs by dendritic cells (DCs) in vivo. The 40 nm γ-PGA-Phe NPs migrated more rapidly to the lymph nodes and were taken up by a greater number of DCs compared with 100 and 200 nm NPs. On the other hand, when the amount of γ-PGA-Phe NPs taken up per DC was evaluated, it was higher for 100 and 200 nm NPs than for 40 nm NPs, which suggests that the larger γ-PGA-Phe NPs can deliver a large amount of antigen to a single DC compared with smaller NPs. Furthermore, when examined the maturation of DCs in lymph nodes, 40 nm γ-PGA-Phe NPs efficiently stimulated DCs. These results suggest that the activation, uptake behavior by APCs, migration to lymph nodes, and DC maturation can be controlled by the size of γ-PGA-Phe NPs.

Manipulating the antigen-specific immune response by the hydrophobicity of amphiphilic poly(γ-glutamic acid) nanoparticles

The new generation vaccines are safe but poorly immunogenic, and thus they require the use of adjuvants. However, conventional vaccine adjuvants fail to induce potent cellular immunity, and their toxicity and side-effects hinder the clinical use. Therefore, a vaccine adjuvant which is safe and can induce an antigen-specific cellular immunity-biased immune response is urgently required. In the development of nanoparticle-based vaccine adjuvants, the hydrophobicity is one of the most important factors. It could control the interaction between the encapsulated antigens and/or nanoparticles with immune cells. In this study, nanoparticles (NPs) composed of amphiphilic poly(γ-glutamic acid)-graft-L-phenylalanine ethyl ester (γ-PGA-Phe) with various grafting degrees of hydrophobic side chains were prepared to evaluate the effect of hydrophobicity of vaccine carriers on the antigen encapsulation behavior, cellular uptake, activation of dendritic cells (DCs), and induction of antigen-specific cellular immunity-biased immune responses. These NPs could efficiently encapsulate antigens, and the uptake amount of the encapsulated antigen by DCs was dependent on the hydrophobicity of γ-PGA-Phe NPs. Moreover, the activation potential of the DCs and the induction of antigen-specific cellular immunity were correlated with the hydrophobicity of γ-PGA-Phe NPs. By controlling the hydrophobicity of antigen-encapsulated γ-PGA-Phe NPs, the activation potential of DCs was able to manipulate about 5 to 30-hold than the conventional vaccine, and the cellular immunity was about 10 to 40-hold. These results suggest that the hydrophobicity of NPs is a key factor for changing the interaction between NPs and immune cells, and thus the induction of cellular immunity-biased immune response could be achieved by controlling the hydrophobicity of them.

Vaccine delivery using nanoparticles

Vaccination has had a major impact on the control of infectious diseases. However, there are still many infectious diseases for which the development of an effective vaccine has been elusive. In many cases the failure to devise vaccines is a consequence of the inability of vaccine candidates to evoke appropriate immune responses. This is especially true where cellular immunity is required for protective immunity and this problem is compounded by the move toward devising sub-unit vaccines. Over the past decade nanoscale size (<1000 nm) materials such as virus-like particles, liposomes, ISCOMs, polymeric, and non-degradable nanospheres have received attention as potential delivery vehicles for vaccine antigens which can both stabilize vaccine antigens and act as adjuvants. Importantly, some of these nanoparticles (NPs) are able to enter antigen-presenting cells by different pathways, thereby modulating the immune response to the antigen. This may be critical for the induction of protective Th1-type immune responses to intracellular pathogens. Their properties also make them suitable for the delivery of antigens at mucosal surfaces and for intradermal administration. In this review we compare the utilities of different NP systems for the delivery of sub-unit vaccines and evaluate the potential of these delivery systems for the development of new vaccines against a range of pathogens.

Vaccine delivery using nanoparticles

Vaccination has had a major impact on the control of infectious diseases. However, there are still many infectious diseases for which the development of an effective vaccine has been elusive. In many cases the failure to devise vaccines is a consequence of the inability of vaccine candidates to evoke appropriate immune responses. This is especially true where cellular immunity is required for protective immunity and this problem is compounded by the move toward devising sub-unit vaccines. Over the past decade nanoscale size (<1000 nm) materials such as virus-like particles, liposomes, ISCOMs, polymeric, and non-degradable nanospheres have received attention as potential delivery vehicles for vaccine antigens which can both stabilize vaccine antigens and act as adjuvants. Importantly, some of these nanoparticles (NPs) are able to enter antigen-presenting cells by different pathways, thereby modulating the immune response to the antigen. This may be critical for the induction of protective Th1-type immune responses to intracellular pathogens. Their properties also make them suitable for the delivery of antigens at mucosal surfaces and for intradermal administration. In this review we compare the utilities of different NP systems for the delivery of sub-unit vaccines and evaluate the potential of these delivery systems for the development of new vaccines against a range of pathogens.

Structure-dependent immunostimulatory effect of CpG oligodeoxynucleotides and their delivery system

Unmethylated cytosine-phosphate-guanosine (CpG) oligodeoxynucleotides (ODNs) are recognized by Toll-like receptor 9 (TLR9) found in antigen-presenting cells and B cells and can activate the immune system. Using CpG ODNs as an adjuvant has been found to be effective for treating infectious diseases, cancers, and allergies. Because natural ODNs with only a phosphodiester backbone are easily degraded by nuclease (deoxyribonuclease [DNase]) in serum, CpG ODNs with a phosphorothioate backbone have been studied for clinical application. CpG ODNs with a phosphorothioate backbone have raised concern regarding undesirable side effects; however, several CpG ODNs with only a phosphodiester backbone have been reported to be stable in serum and to show an immunostimulatory effect. In recent years, research has been conducted on delivery systems for CpG ODNs using nanoparticles (NPs). The advantages of NP-based delivery of CpG ODN include (1) it can protect CpG ODN from DNase, (2) it can retain CpG ODN inside the body for a long period of time, (3) it can improve the cellular uptake efficiency of CpG ODN, and (4) it can deliver CpG ODN to the target tissues. Because the target cells of CpG ODN are cells of the immune system and TLR9, the receptor of CpG ODN is localized in endolysosomes, CpG ODN delivery systems are required to have qualities different from other nucleic acid drugs such as antisense DNA and small interfering RNA. Studies until now have reported various NPs as carriers for CpG ODN delivery. This review presents DNase-resistant CpG ODNs with various structures and their immunostimulatory effects and also focuses on delivery systems of CpG ODNs that utilize NPs. Because CpG ODNs interact with TLR9 and activate both the innate and the adaptive immune system, the application of CpG ODNs for the treatment of cancers, infectious diseases, and allergies holds great promise.

Formation of unimer nanoparticles by controlling the self-association of hydrophobically modified poly(amino acid)s

Amphiphilic block or graft copolymers have been demonstrated to form a variety of self-assembled nano/microstructures in selective solvents. In this study, the self-association behavior of biodegradable graft copolymers composed of poly(γ-glutamic acid) (γ-PGA) as the hydrophilic segment and L-phenylalanine (Phe) as the hydrophobic segment in aqueous solution was investigated. The association behavior and unimer nanoparticle formation of these γ-PGA-graft-Phe (γ-PGA-Phe) copolymers in aqueous solution were characterized with a focus on the effect of the Phe grafting degree on the intra- and interpolymer association of γ-PGA-Phe. The particle size and number of polymer aggregates (N(agg)) in one particle of the γ-PGA-Phe depended on the Phe grafting degree. The size of γ-PGA-Phe with 12, 27, 35, or 42% Phe grafting (γ-PGA-Phe-12, -27, -35, or -42) was about 8-14 nm and the N(agg) was about 1, supporting the presence of a unimolecular graft copolymer in PBS. The pyrene fluorescence data indicated that γ-PGA-Phe-35 and -42 have hydrophobic domains formed by the intrapolymer association of Phe attached to γ-PGA. These results suggest that the Phe grafting degree is critical to the association behavior of γ-PGA-Phe and that γ-PGA-Phe-35 and -42 could form unimer nanoparticles. Moreover, when γ-PGA-Phe-42 dissolved in DMSO was added to various concentrations of NaCl solution, the particle size and N(agg) could be easily controlled by changing the NaCl concentration during the formation of the particles. These results suggest that biodegradable γ-PGA-Phe is useful for the fabrication of very small nanoparticles. It is expected that γ-PGA-Phe nanoparticles, including unimer particles, will have great potential as multifunctional carriers for pharmaceutical and biomedical applications, such as drug and vaccine delivery systems.