Transport of saquinavir across human brain-microvascular endothelial cells by poly(lactide-co-glycolide) nanoparticles with surface poly-(γ-glutamic acid)

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.

Brain drug delivery and neurodegenerative diseases: Polymeric PLGA-based nanoparticles as a forefront platform

The discovery of effective drugs for the treatment of neurodegenerative disorders (NDs) is a deadlock. Due to their complex etiology and high heterogeneity, progresses in the development of novel NDs therapies have been slow, raising social/economic and medical concerns. Nanotechnology and nanomedicine evolved exponentially in recent years and presented a panoply of tools projected to improve diagnosis and treatment. Drug-loaded nanosystems, particularly nanoparticles (NPs), were successfully used to address numerous drug glitches, such as efficacy, bioavailability and safety. Polymeric nanoparticles (PNPs), mainly based on polylactic-co-glycolic acid (PLGA), have been already validated and approved for the treatment of cancer, neurologic dysfunctions and hormonal-related diseases. Despite promising no PNPs-based therapy for neurodegenerative disorders is available up to date. To stimulate the research in the area the studies performed so far with polylactic-co-glycolic acid (PLGA) nanoparticles as well as the techniques aimed to improve PNPs BBB permeability and drug targeting were revised. Bearing in mind NDs pharmacological therapy landscape huge efforts must be done in finding new therapeutic solutions along with the translation of the most promising results to the clinic, which hopefully will converge in the development of effective drugs in a foreseeable future.

Natural bio-based monomers for biomedical applications: a review

In recent years, synthetic and semi-synthetic polymer materials have been widely used in various applications. Especially concerning biomedical applications, their biocompatibility, biodegradability, and non-toxicity have increased the interest of researchers to discover and develop new products for the well-being of humanity. Among the synthetic and semi-synthetic materials, the use of natural bio-based monomeric materials presents a possible novel avenue for the development of new biocompatible, biodegradable, and non-toxic products. The purpose of this article is to review the information on the role of natural bio-based monomers in biomedical applications. Increased eco-friendliness, biocompatibility, biodegradability, non-toxicity, and intrinsic biological activity are some of the attributes which make itaconic, succinic, citric, hyaluronic, and glutamic acids suitable potential materials for biomedical applications. Herein, we summarize the most recent advances in the field over the past ten years and specifically highlight new and interesting discoveries in biomedical applications. Natural origin acid-based bio-monomers for biomedical applications.

Enhancement of saquinavir absorption and accumulation through the formation of solid drug nanoparticles

Background

Nanotechnology is now considered a promising drug delivery method for orally administered hydrophobic drugs to their sites of action. The effect of nanodispersion on cellular transport and accumulation of saquinavir (SQV) was investigated.

Methods

The transport of five solid drug nanoparticle (SDN) SQV formulations along Caco-2 cell monolayers (CCM) was compared to that of standard SQV. The SDNs were prepared using SQV mesylate (20%), Pluronic F127 (10%) plus five other excipients (HPMC, PVP, PVA, Lecithin S75 and Span 80) in different proportions. Cellular accumulation in CEM parental and CEMVBL (P-gp overexpressing) cells was conducted to ascertain the effect of nanodispersion on P-gp mediated efflux of SQV. All SDN formulations were dissolved in water, whereas SQV in DMSO to improve solubility. Quantification was via HPLC.

Results

From transport results, an SDN sample composed of SQV mesylate/Pluronic F127 plus HPMC (70%) and had a 24% increase in apparent absorption compared to standard SQV, largely driven by a 38% reduction in basolateral to apical permeation. Additionally, the formulation and two others (SQV mesylate/Pluronic F127 alone; and + HPMC (65%)/Lecithin [5%]) accumulated more significantly in CEM cells, suggesting enhanced delivery to these cells. Moreover, accumulation and transport of the three SDNs compared well to that of SQV despite being dissolved in water, suggestive of improved dissolution. The inclusion of PVA resulted in increased efflux.

Conclusion

The use of HPMC and Pluronic F127 produced SQV SDNs with improved permeation in Caco-2 cells and improved accumulation in CEM cells, but negative effects with PVA.

Harnessing nanostructured systems for improved treatment and prevention of HIV disease

Combination antiretroviral therapy effectively controls human immunodeficiency virus (HIV) viral replication, delaying the progression to acquired immune deficiency syndrome and improving and extending quality of life of patients. However, the inability of antiretroviral therapeutics to target latent virus and their poor penetration of viral reserve tissues result in the need for continued treatment for the life of the patient. Side effects from long-term antiretroviral use and the development of drug resistance due to patient noncompliance are also continuing problems. Nanostructured systems of antiretroviral therapeutics have the potential to improve targeted delivery to viral reservoirs, reduce drug toxicity, and increase dosing intervals, thereby improving treatment outcomes and enhancing patient adherence. Despite these advantages, very few nanostructured antiretroviral delivery systems have made it to clinical trials due to challenges in preclinical and clinical development. In this context, we review the current challenges in HIV disease management, and the recent progress in leveraging the unique performance of nanostructured systems in therapeutic delivery for improved treatment and prevention of this incurable human disease.

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.

Peptides and proteins used to enhance gold nanoparticle delivery to the brain: preclinical approaches

An exciting and emerging field in nanomedicine involves the use of gold nanoparticles (AuNPs) in the preclinical development of new strategies for the treatment and diagnosis of brain-related diseases such as neurodegeneration and cerebral tumors. The treatment of many brain-related disorders with AuNPs, which possess useful physical properties, is limited by the blood–brain barrier (BBB). The BBB highly regulates the substances that can permeate into the brain. Peptides and proteins may represent promising tools to improve the delivery of AuNPs to the central nervous system (CNS). In this review, we summarize the potential applications of AuNPs to CNS disorders, discuss different strategies based on the use of peptides or proteins to improve the delivery of AuNPs to the brain, and examine the intranasal administration route, which bypasses the BBB. We also analyze the potential neurotoxicity of AuNPs and the perspectives and new challenges concerning the use of peptides and proteins to enhance the delivery of AuNPs to the brain. The majority of the work described in this review is in a preclinical stage of experimentation, or in select cases, in clinical trials in humans. We note that the use of AuNPs still requires substantial study before being translated into human applications. However, for further clinical research, the issues related to the potential use of AuNPs must be analyzed.

Targeting microbubbles-carrying TGFβ1 inhibitor combined with ultrasound sonication induce BBB/BTB disruption to enhance nanomedicine treatment for brain tumors

The clinical application of chemotherapy for brain cancer tumors remains a challenge due to difficulties in the transport of therapeutic agents across the blood-brain barrier/blood-tumor barrier (BBB/BTB). In this study, we developed des-octanoyl ghrelin-conjugated microbubbles (GMB) loaded with TGFβ1 inhibitor (LY364947) (GMBL) to induce BBB/BTB disruption for ultrasound (US) sonication with GMBL. The in-vitro stability study showed that GMB was pretty stable over one month. The in-vivo study showed that the accumulation of superparamagnetic iron oxide nanoparticles (SPION) in the sonicated tumor was significantly higher for focused US sonication in the presence of GMBL, indicating that GMBL/US can locally disrupt BBB/BTB to promote vascular permeability of nanoparticles. In addition, the combination of folate-conjugated polymersomal doxorubicin (FPD) and GMBL/US (FPD+GMBL/US) achieved the best anti-glioma effect and significant improvement in the overall survival time for brain tumor-bearing mice. When combined with focused US, GMBL facilitated local BBB/BTB disruption and simultaneously released LY364947 to decrease the pericyte coverage of the endothelium at the targeted brain tumor sites, resulting in enhanced accumulation and antitumor activity of FPD. The overall results indicate that GMBL/US owns a great potential for non-invasive targeting delivery of nanomedicine across the BBB to treat central nervous system (CNS) diseases.

Gemini quaternary ammonium-incorporated biodegradable multiblock polyurethane micelles for brain drug delivery

Gemini quaternary ammonium (GQA) incorporated biodegradable multiblock polyurethane (BMPUs) micelles could transport drug across blood–brain barrier and improve brain drug accumulation.

Angiopep-pluronic F127-conjugated superparamagnetic iron oxide nanoparticles as nanotheranostic agents for BBB targeting

Pluronic® F127-modified water-dispersible poly(acrylic acid)-bound iron oxide (PF127-PAAIO) nanoparticles have been prepared as diagnostic agents. A blood-brain-barrier penetrating peptide, angiopep-2 (ANG), was further conjugated onto the surface of the PF127-PAAIO (ANG-PF127-PAAIO) for brain targeting. The ANG-PF127-PAAIO shows negligible cell cytotoxicity, better cellular uptake, and higher T₂-weighted image enhancement than the PF127-PAAIO in U87 cells. Using an ex vivo blood-brain barrier (BBB) model, we showed that the ANG-PF127-PAAIO shows better permeability to bypass the BBB. This is because the ANG-PF127-PAAIO has a dual-targeting ability, recognition of the low-density lipoprotein receptor-related protein and clathrin-mediated receptor on the U87 surface. Thus, the ANG-PF127-PAAIO is a potential nanotheranostic agent for brain dysfunction.

Nanotechnology: a magic bullet for HIV AIDS treatment

Human immunodeficiency virus (HIV) infection has become devastating in last a few years. Nearly 7400 new infection cases are coming every day. Highly active antiretroviral therapy (HAART), which involves combination of at least three antiretroviral (ARV) drugs, has been used to extend the life span of the HIV-infected patients. HAART has played an important role to reduce mortality rate in the developed countries but in the developing countries condition is still worst with millions of people being infected by this disease. For the improvement of the situation, nanotechnology-based drug system has been explored for the HIV therapeutics. Nanosystems used for HIV therapeutics offer some unique advantage like enhancement of bioavailability, water solubility, stability, and targeting ability of ARV drugs. Main nanotechnology-based systems explored for HIV therapeutics are liposomes, nanoparticles, niosomes, polymeric micelles, and dendrimers. Present manuscript reviews conventional method of HIV therapeutics and recent advances in the field of nanotechnology-based systems for treatment of HIV-AIDS.

Polymersomes conjugated with des-octanoyl ghrelin and folate as a BBB-penetrating cancer cell-targeting delivery system

Chemotherapy for brain cancer tumors remains a big challenge for clinical medicine due to the inability to transport sufficient drug across the blood-brain barrier (BBB) and the poor penetration of drug into the tumors. To effectively treat brain tumors and reduce side effects on normal tissues, both des-octanoyl ghrelin and folate conjugated with polymersomal doxorubicin (GFP-D) was developed in this study to help transport across the BBB and target the tumor as well. The size measurements revealed that this BBB-penetrating cancer cell-targeting GFP-D was about 85 nm. In-vitro experiments with a BBB model and C6 glioma cells demonstrated that GFP-D owned a robust penetrating-targeting function for drug delivery. In C6 cell viability tests, GFP-D exhibited an inhibitory effect significantly different from the unmodified polymersomal doxorubicin (P-D). In-vivo antitumor experiments showed that GFP-D performed a much better anti-glioma effect and presented a significant improvement in the overall survival of the tumor-bearing mice as compared to the treatments with free doxorubicin (Dox), liposomal doxorubicin (L-D), P-D, or single ligand conjugated P-D. In addition, Cy 5.5 was used as a probe to investigate the delivery property of this penetrating-targeting delivery system. The overall experimental results indicate that this BBB-penetrating cancer cell-targeting GFP is a highly potential nanocarrier for the treatment of brain tumors.

Cationic solid lipid nanoparticles with cholesterol-mediated surface layer for transporting saquinavir to the brain

Cholesterol-mediated cationic solid lipid nanoparticles (CSLNs) were formulated with esterquat 1 (EQ 1) and stearylamine as positively charged external layers on hydrophobic internal cores of cacao butter. These CSLNs were employed to deliver saquinavir (SQV) to the brain. The permeability of SQV across the blood-brain barrier (BBB) using SQV-loaded CSLNs (SQV-CSLNs) was estimated with an in vitro model of a monolayer of human brain-microvascular endothelial cells (HBMECs) regulated by human astrocytes. The results revealed that the average diameter of SQV-CSLNs diminished when the weight percentage of cholesterol and EQ 1 increased. The morphological images indicated a uniform size of SQV-CSLNs with compact lipid structure. In addition, an increasing weight percentage of cholesterol and EQ 1 enhanced the zeta potential of SQV-CSLNs. The fluorescent staining demonstrated that HBMECs could internalize SQV-CSLNs. An increase in the weight percentage of cholesterol and EQ 1 also promoted the uptake of SQV-CSLNs by HBMECs. Moreover, a high content of cholesterol and EQ 1 in SQV-CSLNs increased the BBB permeability of SQV. The cholesterol-mediated SQV-CSLNs can be an efficacious drug delivery system for brain-targeting delivery of antiviral agents.

Direct colorimetric biosensing of mercury(II) ion based on aggregation of poly-(γ-glutamic acid)-functionalized gold nanoparticles

A simple and sensitive method for colorimetric detection of mercury ion (Hg(2+)) has been developed by using a poly (γ-glutamic acid) functionalized gold nanoparticles (PGA-AuNPs) system. Electrostatic self-assembly technique was used to assemble negatively charged PGA on the surface of positively charged CTAB-capped AuNPs. With the increase of Hg(2+) concentration, the color of the solution would progress from light red to purple blue. The results showed that the absorbance ratio (A750/A580) was linear with the Hg(2+) concentration in the range of 0.01-10 μM and from 50 to 300 μM, with the correlation coefficients of 0.998 and 0.991, respectively. The reported probe is suitable for real-time detection of Hg(2+) in water with the limit of detection (LOD) of 1.9 nM obtained by UV-vis spectrum, and exhibits selectivity toward one order of magnitude over other metal ions. This approach was applied successfully to the determination of Hg(2+) in tap water and mineral water, and the recoveries were from 90% to 103% and from 103.53% to 113%, respectively. The proposed method is rapid, low-cost and free of complex equipment, making it possible to analyze Hg(2+) in various water samples.

TATVHL peptide-grafted alginate/poly(γ-glutamic acid) scaffolds with inverted colloidal crystal topology for neuronal differentiation of iPS cells

The neuronal differentiation of induced pluripotent stem (iPS) cells in scaffolding biomaterials is an emerging issue in nervous regeneration and repair. This study presents the production of neuron-lineage cells from iPS cells in inverted colloidal crystal (ICC) scaffolds comprising alginate, poly(γ-glutamic acid) (γ-PGA), and TATVHL peptide. The ability of iPS cells to differentiate toward neurons in the constructs was demonstrated by flow-cytometeric sorting and immunochemical staining. The results revealed that hexagonally arrayed microspheres molded alginate/γ-PGA hydrogel into ICC topology with adequate interconnected pores. An increase in the quantity of surface TATVHL peptide enhanced the atomic ratio of nitrogen and the adhesion efficiency of iPS cells in constructs. However, the effect of TATVHL peptide on the viability of iPS cells was insignificant. The adhesion and viability of iPS cells in ICC constructs was higher than those in freeform ones. TATVHL peptide raised the percentage of β III tubulin-identified cells differentiating from iPS cells, indicating that TATVHL peptide stimulated the neuronal development in alginate/γ-PGA ICC constructs. TATVHL peptide-grafted alginate/γ-PGA ICC scaffolds can be promising for establishing nerve tissue from iPS cells.

Differentiation of induced pluripotent stem cells toward neurons in hydrogel biomaterials

Regeneration of nerve tissue is one of the most significant challenges in contemporary surgical therapy for nervous system injury. This study presents the neuronal differentiation of induced pluripotent stem (iPS) cells in hydrogels comprising alginate and poly(γ-glutamic acid) (γ-PGA) with surface neuron growth factor (NGF). Differentiating iPS cells in NGF-grafted alginate/γ-PGA constructs were identified by immunochemical staining of anti-SSEA-1 and anti-β III tubulin. The results revealed that the pore diameter of hydrogels increased with an increasing weight ratio of alginate to γ-PGA. The porosity slightly decreased with an increasing weight ratio of alginate to hydrogel. In addition, an increase in the weight ratio of alginate to hydrogel raised the swelling ratio. Morphological images of differentiating iPS cells in NGF-grafted alginate/γ-PGA constructs exhibited neuronal characteristics. The surface NGF enhanced the intensity of β III tubulin and inhibited the intensity of SSEA-1 expressed by differentiating iPS cells in cultured constructs, indicating the differentiation of iPS cells toward neurons. NGF-grafted alginate/γ-PGA hydrogels can be efficient biomaterials in the production of neurons from iPS cells for animal study and preclinical trial.

Polymeric nanocarriers for controlled and enhanced delivery of therapeutic agents to the CNS

Polymeric nanocarriers are versatile structures that can be engineered to obtain high drug loading, good delivery yields and tunable release kinetics. Moreover, the particle surface can be modified for selective targeting of organs or tissues. In particular, polymeric nanocarriers can be conjugated with functional groups promoting translocation through the blood–brain barrier, thus providing a promising system to deliver therapeutic agents and/or diagnostic probes to the brain. Here we review recent literature on the preparation and characterization of polymeric nanoparticles as potential agents for drug delivery to the CNS, with an emphasis on materials chemistry and functionalization strategies for improved selectivity and delivery. Finally, we underline the immunotoxicological aspects of this class of nanostructured materials in view of potential clinical applications.

Methylmethacrylate-sulfopropylmethacrylate nanoparticles with surface RMP-7 for targeting delivery of antiretroviral drugs across the blood-brain barrier

This study investigates the capability of methylmethacrylate-sulfopropylmethacrylate (MMA-SPM) nanoparticles (NPs) with grafted RMP-7 (RMP-7/MMA-SPM NPs) to deliver stavudine (D4T), delavirdine (DLV), and saquinavir (SQV) across the blood-brain barrier (BBB). The permeability coefficients of the three drugs across the BBB were evaluated by a co-culture model containing human brain-microvascular endothelial cells and human astrocytes. An increase in the concentration of ammonium persulfate (APS), the polymerization initiator, enhanced the particle size of drug-loaded RMP-7/MMA-SPM NPs. When the concentration of APS was 0.6%, the average particle diameter was smaller than 50 nm. These spherical drug carriers were uniform in size and displayed a dominant topography of discrete hillocks and deep pits in deposited film. Smaller RMP-7/MMA-SPM NPs yielded a larger drug loading efficiency. The order of drug in the loading efficiency and in the particle uptake was, respectively, D4T>DLV>SQV and D4T>SQV>DLV. Endocytosis of RMP-7/MMA-SPM NPs and tight junction mediation can improve the permeability of D4T, DLV, and SQV across the BBB.