Novel pH-sensitive chitosan-derived micelles loaded with paclitaxel

Curcumin-loaded multifunctional chitosan gold nanoparticles: An enhanced PDT/PTT dual-modal phototherapeutic and pH-responsive antimicrobial agent

Overuse of antibiotics has led to the emergence of multidrug resistant (MDR) bacteria.. Photothermal (PTT) and photodynamic therapy (PDT) have may be effective alternatives for antibiotics in the treatment of bacterial infections. In this study, based on chitosan (CS)-coated gold nanoparticles, a pH stimulus-responsive drug delivery system was developed, which can anchor to the cell membrane for photodynamic therapy and photothermal therapy, and enhance the therapeutic potential of curcumin (Cur). Release experiments showed that AuNPs/CS-Cur nanocomposites released curcumin in a pH-dependent manner, which may facilitate the drug to be delivered to the acidic bacterial infection environment. CS as the outer layer covered on gold nanoparticles could improve the dispersibility of Cur in aqueous solution, gold nanoparticles prevent rapid photobleaching of curcumin, thus ensuring the yield of singlet oxygen under irradiation, and enhance the electrostatic binding with bacteria cell membrane. Under light conditions, AuNPs/CS-Cur can produce a large amount of reactive oxygen species and heat to kill S. aureus and E. coli. Compared with free Cur-mediated PDT, the complex significantly improved the synergistic PTT/PDT photoinactivation ability against S. aureus and E. coli. In addition, AuNPs/CS-Cur had good biocompatibility. Therefore, AuNPs/CS-Cur possessed the characteristics of electrostatic targeting, photodynamic and photothermal antibacterial therapy, which would become an efficient and safe antibacterial nano-platform and provide new ideas for the treatment of bacterial infection.

Natural and Synthetic Micelles for Delivery of Small Molecule Drugs, Imaging Agents and Nucleic Acids

The poor solubility, lack of targetability, quick renal clearance, and degradability of many therapeutic and imaging agents strongly limit their applications inside the human body. Amphiphilic copolymers having self-assembling properties can form core-shell structures called micelles, a promising nanocarrier for hydrophobic drugs, plasmid DNA, oligonucleotides, small interfering RNAs (siRNAs) and imaging agents. Fabrication of micelles loaded with different pharmaceutical agents provides numerous advantages including therapeutic efficacy, diagnostic sensitivity, and controlled release to the desired tissues. Moreover, due to their smaller particle size (10-100 nm) and modified surfaces with different functional groups (such as ligands) help them to accumulate easily in the target location, enhancing cellular uptake and reducing unwanted side effects. Furthermore, the release of the encapsulated agents may also be triggered from stimuli-sensitive micelles at different physiological conditions or by an external stimulus. In this review article, we discuss the recent advancement in formulating and targeting different natural and synthetic micelles including block copolymer micelles, cationic micelles, and dendrimers-, polysaccharide- and protein-based micelles for the delivery of different therapeutic and diagnostic agents. Finally, their applications, outcomes, and future perspectives have been summarized.

Drug Delivery Platforms Containing Thermoresponsive Polymers and Mucoadhesive Cellulose Derivatives: A Review of Patents

Nowadays, the development of mucoadhesive systems for drug delivery has gained keen interest, with enormous potential in applications through different routes. Mucoadhesion characterizes an attractive interaction between the pharmaceutical dosage form and the mucosal surface. Many polymers have shown the ability to interact with mucus, increasing the residence time of local and/or systemic administered preparations, such as tablets, patches, semi-solids, and micro and nanoparticles. Cellulose is the most abundant polymer on the earth. It is widely used in the pharmaceutical industry as an inert pharmaceutical ingredient, mainly in its covalently modified forms: methylcellulose, ethylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, and carboxymethylcellulose salts. Aiming to overcome the drawbacks of oral, ocular, nasal, vaginal, and rectal routes and thereby maintaining patient compliance, innovative polymer blends have gained the interest of the pharmaceutical industry. Combining mucoadhesive and thermoresponsive polymers allows for simultaneous in situ gelation and mucoadhesion, thus enhancing the retention of the system at the site of administration and drug availability. Thermoresponsive polymers have the ability to change physicochemical properties triggered by temperature, which is particularly interesting considering the physiological temperature. The present review provides an analysis of the main characteristics and applications of cellulose derivatives as mucoadhesive polymers and their use in blends together with thermoresponsive polymers, aiming at platforms for drug delivery. Patents were reviewed, categorized, and discussed, focusing on the applications and pharmaceutical dosage forms using this innovative strategy. This review manuscript also provides a detailed introduction to the topic and a perspective on further developments.

Multifunctional polymeric micellar nanomedicine in the diagnosis and treatment of cancer

Polymeric micelles are a prevalent topic of research for the past decade, especially concerning their fitting ability to deliver drug and diagnostic agents. This delivery system offers outstanding advantages, such as biocompatibility, high loading efficiency, water-solubility, and good stability in biological fluids, to name a few. The multifunctional polymeric micellar architect offers the added capability to adapt its surface to meet the looked-for clinical needs. This review cross-talks the recent reports, proof-of-concept studies, patents, and clinical trials that utilize polymeric micellar family architectures concerning cancer targeted delivery of anticancer drugs, gene therapeutics, and diagnostic agents. The manuscript also expounds on the underlying opportunities, allied challenges, and ways to resolve their bench-to-bedside translation for allied clinical applications.

Construction of an environmentally friendly octenylsuccinic anhydride modified pH-sensitive chitosan nanoparticle drug delivery system to alleviate inflammation and oxidative stress

An environmentally friendly octenylsuccinic anhydride modified pH-sensitive chitosan-octenylsuccinic anhydride (OSA-CS) was synthesized. The critical micelle concentration (CMC) of the modified chitosan was 27 μg/mL, the graft polymers can form solubilized curcumin (CUR) and quercetin (QUE) nanoparticles. The drug-loaded nanoparticles had high encapsulation efficiency and drug loading content, the self-assembly of graft polymers formed spherical uniform nanoparticles with an approximate diameter of 150-180 nm. The nanoparticles were stable under storage conditions and in serum. The results revealed that OSA-CS exhibited excellent biocompatibility, no cytotoxicity. Additionally, the results of pH sensitivity and drug release experiments showed that the nanoparticles were highly sensitive to weakly acidic conditions (pH 6.0) and showed a faster release rate, while they were reasonably stable at physiological conditions (pH 7.4). The drug-loaded nanoparticles exhibited higher cellular uptake in vitro, and exhibited stronger anti-inflammatory and antioxidant efficacy. Therefore, OSA-CS-based nanoparticles are a promising hydrophobic drug delivery system for pH-response targeting therapy.

Ultrasensitive (Co)polymers Based on Poly(methacrylamide) Structure with Fining-Tunable pH Responsive Value

Novel pH responsive copolymers with tertiary amine groups were prepared by free radical polymerization with 2-(dialkylamino)ethyl methacrylate monomers. These polymers were pH sensitive with the ability to be responsively fine-tuned in aqueous solution, which was proven through titration, transmittance measurements, and proton nuclear magnetic resonance spectroscopy. The polymers were soluble in water at low pH values, induced by electrostatic repulsion between amine groups, and aggregated above their pKa value due to the hydrophobic effect of the alkyls. The pH responsive values were precisely tuned from 7.4 to 4.8 by increasing the hydrophobic monomer ratio. Our work provides a novel approach for the development of ultrasensitive pH-responsive polymers for application in biomedical materials.

Novel amphiphilic folic acid-cholesterol-chitosan micelles for paclitaxel delivery

In order to decrease the toxicity of paclitaxel (PTX) and increase the efficiency, we developed an amphiphilic PTX injection system using a biodegradable and biocompatible polymer synthesized by folic acid, cholesterol, and chitosan (FACC). This FACC-based polymer had a low critical concentration (64.13μg/ml) and could self-assemble in aqueous condition to form nanoscale micelles. The particle sizes of FACC-PTX micelles were 253.2±0.56 nm, the encapsulation efficiency and loading capacity of these FACC-PTX micelles were 65.1±0.23% and 9.1±0.16%, respectively. The cumulative release rate was about 85% at pH 5.0 which was higher than that at pH 7.4 (76%). This pH-dependent release behavior was highly suggesting that PTX release from FACC-PTX micelles might be higher in a weak acidic tumor microenvironment and lower toxic for normal cells. The anti-cancer effectiveness of FACC-PTX micelles was investigated by in vitro cytotoxicity and targeting study. The results revealed that FACC micelles have non-toxic on cells as evidenced by high cell viability found (86% to 100%) in the cells cultured with various concentrations of FACC micelles (1 to 500 μg/ml). Targeting study indicated that the cytotoxic efficacy of FACC-PTX micelles was significantly higher than that with Taxol® in the Hela cells (folate receptor-positive cells). These findings indicated that the anticancer efficiency of PTX can be enhanced by adding some cancer cell positive receptor into drug carrier and the FACC micelle was a potential tumor targeting carrier for PXT delivery.

Dual-sensitive chitosan derivative micelles for site-specific drug release in the treatment of chicken coccidiosis

Here, we report a “dual-sensitive” drug delivery platform packaged with anti-coccidia drug diclazuril (DIC) applied in the field of intestinal-targeted administration.

A New Water-Soluble Nanomicelle Formed through Self-Assembly of Pectin-Curcumin Conjugates: Preparation, Characterization, and Anticancer Activity Evaluation

Curcumin is a dominating active component of Curcuma longa and has been studied widely because of its prominent biological activities. The extremely low aqueous solubility, stability, and bioavailability of curcumin limit its application in the field of medicine. In this study, we developed pectin-curcumin (PEC-CCM) conjugates that could self-assemble water-soluble nanomicelles in aqueous solution. The structure of PEC-CCM conjugates was characterized by ultraviolet-visible spectra, fluorescence spectra, Fourier transform infrared spectroscopy, and ¹H nuclear magnetic resonance spectroscopy. The thermal property of PEC-CCM conjugates was investigated by thermogravimetric analysis. It was found that PEC-CCM conjugates had formed nanomicelles in aqueous medium via self-assembly. These nanomicelles were observed as small spheres or ellipsoids and aggregated with a size range of 70-190 nm by transmission electron microscopy analysis. In a solution of nanomicelles, the stability of curcumin was improved, and its antioxidant property was preserved. The anticancer activity of PEC-CCM conjugates was quantified by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay using a hepatic cancer cell line (HepG2), a breast cancer cell line (MCF-7), a cervical cancer cell line (HeLa), and a human normal kidney cell line (293A). It was found that the curcumin of PEC-CCM conjugates had a more significant inhibitory effect on cancer cells and was less cytotoxic to normal cells than free curcumin was. PEC-CCM conjugates have great potential for some food and pharmaceutical applications.

A novel pH-sensitive carrier for the delivery of antitumor drugs: histidine-modified auricularia auricular polysaccharide nano-micelles

The study was aimed to design a novel pH-sensitive carrier to deliver antitumor drugs to increase treatment efficiency. Histidine (His)was used to modify auricularia auricular polysaccharide (AAP) by esterification. Proton nuclear magnetic resonance spectrometry was developed to characterize the His-AAP carrier and the His-AAP Paclitaxel (PTX) micelles were prepared by self-assembled organic solvent evaporation. The formation of His-AAP PTX micelles was confirmed by dynamic light-scattering, transmission electron microscopy and high performance liquid chromatography. It was found that the His-AAP PTX micelles possessed a spherical morphology with an average diameter of 157.2 nm and an 80.3% PTX encapsulation efficiency. In vitro release at pH 7.4, 6.5, 5.0 reached 70%, 71%, and 88%, respectively. The cell viability assay and confocal laser scanning microscope were used to evaluate the cytotoxicity and cell uptake of the His-AAP PTX micelles. Compared with Taxol, the IC50 of the His-AAP PTX micelles were lower after incubating for 24 h, 48 h, or 72 h (0.216 versus 0.199, 0.065 versus 0.060, and 0.023 versus 0.005, respectively). In a test of tumor-bearing mice, the His-AAP PTX micelles significantly inhibited tumor growth. These results showed that His-AAP PTX micelles are a highly promising therapeutic system for anticancer therapy.

Synthesis and evaluation of pH-sensitive, self-assembled chitosan-based nanoparticles as efficient doxorubicin carriers

A novel pH-responsive polymer based on amphiphilic N-acetyl histidine and arginine-grafted chitosan was synthesized using N-acetyl histidine as hydrophobic segment and arginine as hydrophilic segment by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide-mediated coupling reactions as anticancer drug delivery system for doxorubicin. The structure of the synthesized polymer was confirmed by Fourier transform infrared and ¹H nuclear magnetic resonance analysis. Due to self-association behavior, N-acetyl histidine and arginine-grafted chitosan structured nanoparticles with in size range of 204 nm. N-acetyl histidine and arginine-grafted chitosan with different substitution degree of N-acetyl histidine were initially prepared and characterized. The critical micelle concentration decreased with increasing substitution degree of N-acetyl histidine. Furthermore, N-acetyl histidine and arginine-grafted chitosan nanoparticles exhibited an acidic pH-triggered aggregation and disassembling nature. The doxorubicin-encapsulated nanoparticles based on synthesized conjugate ( N-acetyl histidine and arginine-grafted chitosan/doxorubicin nanoparticles) showed a sustained drug release pattern, which could be hastened under acidic pH conditions but delayed with increasing substitution degree of N-acetyl histidine. Anticancer effects demonstrated that N-acetyl histidine and arginine-grafted chitosan/doxorubicin nanoparticles could suppress both sensitive and resistant human breast tumor cell line (MCF-7) efficiently in a dose- and time-dependent pattern. Confocal microscopy results evidenced increased cellular uptake and enhanced retention of the synthesized nanoparticles in drug-resistant cells demonstrating better efficacy of nanoparticles over native doxorubicin. These results suggest that N-acetyl histidine and arginine-grafted chitosan/doxorubicin nanoparticles might be promising carriers for delivery of hydrophobic drug doxorubicin against drug-resistant tumors.

Preparation and characterization of DOX loaded keratin nanoparticles for pH/GSH dual responsive release

Smart drug carriers are the current need of the hour in controlled drug delivery applications. In this work, pH and redox dual responsive keratin based drug-loaded nanoparticles (KDNPs) were fabricated through two-step strategies. Keratin nanoparticles were first prepared by desolvation method and chemical crosslinking, followed by electrostatic adsorbing doxorubicin (DOX) to afford drug loaded keratin nanoparticles (KDNPs). The size, size distribution, and morphology of the KDNPs were characterized with dynamic light scattering (DLS) and Scan electronic microscope (SEM). Drug delivery profiles showed that KDNPs exhibited pH and glutathione (GSH) dual-responsive characters. Under tumor tissue/cell microenvironments (more acidic and high GSH level), KDNPs tended to accumulate at the tumor region through a potential enhanced permeability and retention (EPR) effect and perform surface negative-to-positive charge conversion. Hemolysis assay indicated that KDNPs had good blood compatibility. Cellular uptake assay demonstrated that KDNPs could be internalized by A 549 cells through endocytosis. Intriguingly, KDNPs were capable of promoting nitric oxide (NO) release from endogenous donor of S-nitrosoglutathione in the presence of GSH. All of these results demonstrated that keratin based drug carriers had potential for drug/NO delivery and cancer therapy in clinical medicine.

Folate-conjugated dually responsive micelles for targeted anticancer drug delivery

Folate-conjugated dual-responsive micelles were developed, sustained and sensitive drug release from the drug loaded micelles was observed. Folate-targeted micelles showed higher anticancer activity and enhanced cellar uptake than non-targeted ones.

Personalizing Biomaterials for Precision Nanomedicine Considering the Local Tissue Microenvironment

New advances in (nano)biomaterial design coupled with the detailed study of tissue-biomaterial interactions can open a new chapter in personalized medicine, where biomaterials are chosen and designed to match specific tissue types and disease states. The notion of a "one size fits all" biomaterial no longer exists, as growing evidence points to the value of customizing material design to enhance (pre)clinical performance. The complex microenvironment in vivo at different tissue sites exhibits diverse cell types, tissue chemistry, tissue morphology, and mechanical stresses that are further altered by local pathology. This complex and dynamic environment may alter the implanted material's properties and in turn affect its in vivo performance. It is crucial, therefore, to carefully study tissue context and optimize biomaterials considering the implantation conditions. This practice would enable attaining predictable material performance and enhance clinical outcomes.

A micelle-like structure of poloxamer-methotrexate conjugates as nanocarrier for methotrexate delivery

The purpose of this study was to develop a novel featured and flexible methotrexate (MTX) formulation, in which MTX was physically entrapped and chemically conjugated in the same drug delivery system. A series of poloxamer-MTX (p-MTX) conjugates was synthesized, wherein MTX was grafted to poloxamer through an ester bond. p-MTX conjugates could self-assemble into micelle-like structures in aqueous environment and the MTX end was in the inner-core of micelles. Moreover, free MTX could be physically entrapped into p-MTX micelles hydrophobic core region to increase the total drug loading. Importantly, the resulting MTX-loaded p-MTX micelles showed a biphasic release of MTX, with a relative fast release of the entrapped MTX (about 6-7h) followed by a sustained release of the conjugated MTX. The pharmacokinetics study showed that the mean residence time (MRT) was extended in the case of MTX-loaded p-MTX micelles, indicating a delayed MTX elimination from the bloodstream and prolonged in vivo residence time. Besides, the area under curve (AUC) of MTX-loaded p-MTX micelles was greater than free MTX, indicating a drug bioavailability improvement. Overall, MTX-loaded p-MTX micelles might be a promising nanosized drug delivery system for the cancer therapy.

pH-sensitive nanomicelles for controlled and efficient drug delivery to human colorectal carcinoma LoVo cells

BACKGROUND

The triblock copolymers PEG-P(Asp-DIP)-P(Lys-Ca) (PEALCa) of polyethylene glycol (PEG), poly(N-(N',N'-diisopropylaminoethyl) aspartamide) (P(Asp-DIP)), and poly (lysine-cholic acid) (P(Lys-Ca)) were synthesized as a pH-sensitive drug delivery system. In neutral aqueous environment such as physiological environment, PEALCa can self-assemble into stable vesicles with a size around 50-60 nm, avoid uptake by the reticuloendothelial system (RES), and encase the drug in the core. However, the PEALCa micelles disassemble and release drug rapidly in acidic environment that resembles lysosomal compartments.

METHODOLOGY/PRINCIPAL FINDINGS

The anticancer drug Paclitaxel (PTX) and hydrophilic superparamagnetic iron oxide (SPIO) were encapsulated inside the core of the PEALCa micelles and used for potential cancer therapy. Drug release study revealed that PTX in the micelles was released faster at pH 5.0 than at pH 7.4. Cell culture studies showed that the PTX-SPIO-PEALCa micelle was effectively internalized by human colon carcinoma cell line (LoVo cells), and PTX could be embedded inside lysosomal compartments. Moreover, the human colorectal carcinoma (CRC) LoVo cells delivery effect was verified in vivo by magnetic resonance imaging (MRI) and histology analysis. Consequently effective suppression of CRC LoVo cell growth was evaluated.

CONCLUSIONS/SIGNIFICANCE

These results indicated that the PTX-SPION-loaded pH-sensitive micelles were a promising MRI-visible drug release system for colorectal cancer therapy.

Intracellular pH-sensitive delivery CaCO3 nanoparticles templated by hydrophobic modified starch micelles

CaCO₃ nanoparticles were prepared using starch–octanoic acid chemical conjugate micelle solution as a template to improve the acid pH sensitive release profile.

A pH-responsive chitosan-b-poly(p-dioxanone) nanocarrier: formation and efficient antitumor drug delivery

Increasing attention has recently been paid to the fabrication of drug delivery systems with excellent cell internalization and intracellular drug release properties. In this study, an amphiphilic block copolymer of chitosan was synthesized for the first time, which can self-assemble into micelles in a neutral aqueous solution but partially disassemble in an acidic endosomal/lysosomal environment. The antitumor drug, camptothecin (CPT), was encapsulated in the cores of the micelles for tumor cell therapy. In vitro drug release studies demonstrated that the micelles presented a much faster release of CPT at pH 5.0 than at pH 7.4. Blank micelles were found to be nontoxic in preliminary in vitro cytotoxicity assays. Cell experiments showed that the CPT-loaded micelles could be effectively internalized by Hela cells and accomplished a potent antitumor cell efficacy, indicating that the chitosan-based micelles might be an attractive new platform for efficient intracellular drug delivery.

A review on comb-shaped amphiphilic polymers for hydrophobic drug solubilization

Comb-shaped amphiphilic polymers are rapidly emerging as an alternative approach to amphiphilic block copolymers for hydrophobic drug solubilization. These polymers consist of a homopolymer or copolymer backbone to which hydrophobic and hydrophilic pendant groups can be grafted resulting in a comb-like architecture. The hydrophobic pendants may consist of homopolymers, copolymers and other low-molecular weight hydrophobic structures. In this review, we focus on hydrophobically modified preformed homopolymers. Comb-shaped amphiphilic polymers possess reduced critical aggregation concentration values compared with traditional surfactant micelles indicating increased stability with decreased disruption experienced on dilution. They have been fabricated with diverse architectures and multifunctional properties such as site-specific targeting and external stimuli-responsive nature. The application of comb-shaped amphiphilic polymers is expanding; here we report on the progress achieved so far in hydrophobic drug solubilization for both intravenous and oral delivery.

pH-sensitive chitosan-derived nanoparticles as doxorubicin carriers for effective anti-tumor activity: preparation and in vitro evaluation

pH-sensitive self-aggregated nanoparticles (SNPs), based on amphiphilic deoxycholic acid (DOCA) modified carboxymethyl chitosan (DCMC), were prepared for delivery of the anticancer drug doxorubicin (DOX). DCMCs with different degrees of substitution (DS) of DOCA were initially synthesized and characterized. Based on self-aggregation, DCMC formed nanoparticles with size ranging from 87 to 174 nm. The critical aggregation concentration (CAC) decreased on increasing the DS of DOCA. Moreover, the DCMC SNPs showed an acidic pH-induced aggregation and deformation behavior. The DOX-loaded SNPs ([D]NP) exhibited a sustained drug release manner, which could be accelerated by an acidic pH, but delayed by a higher DS of DOCA. Antitumor efficacy results showed that [D]NP could suppress both sensitive and resistant MCF-7 cells effectively in a dose- and time-dependent manner. The enhanced cellular uptake and greater retention of [D]NP in drug-resistant cells, as evidenced by confocal microscopy and flow cytometry, contributed to a superior efficacy of [D]NP over free DOX. These results suggest the potential of DCMC SNPs as carriers for the hydrophobic drug DOX for effective cancer therapy against drug-resistant tumors.