Loading Efficiency Of Nanoparticles Research Articles

Surface Modification Strategies for Chrysin-Loaded Iron Oxide Nanoparticles to Boost Their Anti-Tumor Efficacy in Human Colon Carcinoma Cells.

Enhancing nanoparticles' anti-cancer capabilities as drug carriers requires the careful adjustment of formulation parameters, including loading efficiency, drug/carrier ratio, and synthesis method. Small adjustments to these parameters can significantly influence the drug-loading efficiency of nanoparticles. Our study explored how chitosan and polyethylene glycol (PEG) coatings affect the structural properties, drug-loading efficiency, and anti-cancer efficacy of Fe3O4 nanoparticles (NPs). The loading efficiency of the NPs was determined using FTIR spectrometry and XRD. The quantity of chrysin incorporated into the coated NPs was examined using UV-Vis spectrometry. The effect of the NPs on cell viability and apoptosis was determined by employing the HCT 116 human colon carcinoma cell line. We showed that a two-fold increase in drug concentration did not impact the loading efficiency of Fe3O4 NPs coated with PEG. However, there was a 33 Å difference in the crystallite sizes obtained from chitosan-coated Fe3O4 NPs and drug concentrations of 1:0.5 and 1:2, resulting in decreased system stability. In conclusion, PEG coating exhibited a higher loading efficiency of Fe3O4 NPs compared to chitosan, resulting in enhanced anti-tumor effects. Furthermore, variations in the loaded amount of chrysin did not impact the crystallinity of PEG-coated NPs, emphasizing the stability and regularity of the system.

A recombinant chimeric protein of protective antigen and lethal factor from Bacillus anthracis in polymeric nanocapsules showed a strong immune response in mice: a potential high efficacy vaccine against anthrax.

Anthrax is a serious infectious disease caused by Bacillus anthracis, rod-shaped gram-positive bacteria. The disease infects both humans and animals and causes severe illness. Many vaccines have been developed for anthrax, but the vaccine with very high efficacy is yet to be developed. To overcome the problems of efficacy posed by the existing vaccines, a recombinant chimeric fusion protein containing domain 1 of lethal factor (LFD1) and domain 4 of Bacillus anthracis protective antigen (PA4) was used as antigen in copolymeric nanocapsules (NCs). Accordingly, the solvent evaporation double emulsion method was used to produce NCs containing recombinant chimeric fusion protein (LFD1-PA4). Zeta sizer and potential of nanoparticles, nanoparticle loading efficiency, release pattern of recombinant protein, and the possible effect of polylactic acid-polyethylene glycol (PLA-PEG) nanoparticle production method were investigated. Mice were used to test and evaluate the immune response. The mean titer of antibody produced against loaded LFD1-PA4 compared to free form showed a significant difference. The difference in antibody titer between the groups of once injected, twice injected, and free antigen was significant, and the highest antibody titer was found in the mice twice injected. In addition, a single-time loaded injection showed significantly higher antibodies than the free form injection indicating that loaded LFD1-PA4 into PLA-PEG nanoparticles elicits a stronger immune response. This study showed that LFD1-PA4 fusion protein from Bacillus anthracis served as an active antigen in mice. Also, the nanocarrier (PLA-PEG) containing the antigen can stimulate the immune system in the mice, owing to their controlled release property.

Integration of TaOx with Bi2S3 for Targeted Multimodality Breast Cancer Theranostics.

Early identification and treatment of breast cancer is very important for breast conserving therapy and to improve the prognosis and survival rates of patients. Multifunctional nanotheranostic agents are of particular importance in the field of precise nanomedicine, since they can augment the visualization and treatment of cancer. We developed a novel Bi2S3 nanoparticle coated with a hyaluronic acid (HA)-modified tantalum oxide (TaOx) nanoshell (Bi2S3@TaOx-HA). The as-prepared core/shell nanoparticles exhibited a high Bi2S3 nanoparticle loading efficiency of (67 wt %). The TaOx nanoshell exhibited excellent biocompatibility and computed tomography imaging capacity, and the Bi2S3 nanoparticles exhibited an excellent photothermal transducing performance and computed tomography (CT) and photoacoustic imaging capacity. As a result of these merits, the Bi2S3@TaOx core-shell nanoparticles can act as a theranostic agent for CT/photoacoustically monitored enhanced photothermal therapy. These findings will evoke new interest in future cancer therapeutic strategies based on biocompatible functional nanomaterials.

Phase-transfer-assisted synthesis of cysteine-Ag nanoparticles/graphene oxide nanocomposite and its enhanced performance in antibiosis and biosensing

We report a facile, rapid, phase-transfer-assisted process to prepare Ag nanoparticles (AgNP) loaded graphene oxide (GO) nanocomposite, by using cysteine as a highly-effective phase transfer agent for AgNP movement from organic phase to water and subsequently as a covalent linkage for immobilizing AgNP on GO. The obtained c-Ag/GO nanocomposite possesses high nanoparticle loading efficiency, small particle size and monodispersity, strong binding force and good water dispersibility, which endow it with great potential in a variety of bio-applications. To illustrate potentail application, c-Ag/GO and its derivatives c-Ag/rGO were used for antibiosis and biosensing, respectively. The c-Ag/GO composite demonstrates high antibacterial activity against E. coli with a minimal bactericidal concentration of 10 μg ml−1. The biosensor based on c-Ag/rGO exhibits rapid and sensitive response for uric acid detection with a detection limit of 0.025 μM, a sensitivity of 5.76 μA mM−1 and a wide linear range of 0.025 ∼ 2250 μM. The comparative analysis with relevant nanocomposites also reveals the precedence of c-Ag/GO in these applications, thus highlighting the advantages of the developed preparation method for c-Ag/GO.

In situ syntheses of silver nanoparticles inside silver citrate nanorods via catalytic nanoconfinement effect

Although it is still worth to use silver nanoparticles as antimicrobial agents, silver nanoparticles can also be dangerous to human body, when they used directly to the wound sites. One strategy for avoiding this problem is to embed the nanoparticles in matrices such as hydrogels, polymers, or composites; however, most methods have limitations in terms of nanoparticle loading efficiency and/or pre- or post-treatment required in the manufacturing process. Herein, we introduce two in-situ synthetic methods in which silver nanoparticles are directly synthesized inside silver citrate nanorods that are antimicrobial materials composed of silver and citrate ions. The silver nanoparticles embedded antimicrobial silver citrate nanorods are expected to exhibit a synergistic, long―lasting, and sustainable antimicrobial effect. In addition, this study shows that a large number of nanoparticles can be formed inside silver citrate nanorods with no additional reagents not only at temperatures much lower (as low as 25 °C) than those usually required but also rapidly via electron beam irradiation. The fundamental principles of the proposed efficient syntheses are discussed in terms of the catalytic effect of reactants confined in nanospaces.

In Situ Synthesis of Silver Nanoparticles onto Cotton Fibers Modified with Carboxymethyl Chitosan

Silver nanoparticles(AgNPs) were synthesized onto the modified cotton fabrics with in situ method, in order to fabricate multifunctional fabrics with excellent antibacterial and anti-ultraviolet(UV) properties. Carboxymethyl chitosan(CMCS) was attached on the surface of cotton to enhance the diffusion of silver ions and the loading efficiency of nanoparticles. The obtained samples were then examined by ATR-FTIR, SEM, EDS and ICP-OES, which exhibit outstanding antibacterial behavior and laundering durability against two common pathogenic bacteria: Staphylococcus aureus and Escherichia coli, even after being washed 20 cycles. In addition, the loaded cotton fabrics expressed remarkable UV-protection capability compared to the untreated fabrics.

An acoustic strategy for gold nanoparticle loading in platelets as biomimetic multifunctional carriers.

In recent years, a wide variety of bioinspired colloidal particles with novel cell mimetic functions have been the subject of extensive research in materials science, chemistry, biology, physics, and engineering. However, most of the approaches are derived from natural cell membrane coatings, which are still too primitive compared with living cells. In this study, we have chosen gold nanoparticles (GNPs) to explore the bioactivity response of living platelets and nanoparticle loading efficiency under different ultrasonic intensity and frequency treatment conditions. The results show that GNPs with no surface modification could be easily loaded into intra-platelets by both incubation (30 min) and ultrasonic exposure (1 min) methods. The amount of GNP loading was (4.4 ± 0.9) × 10-3 and (5.8 ± 2.4) × 10-3 pg per platelet upon incubation and acoustic triggering (1 MHz, 0.25 W cm-2), respectively. Although the other US treatment intensities (0.75, 1.50 and 2.25 W cm-2) also promoted higher amounts of GNPs in the platelets, the higher US intensity might bring about partial damage of the platelet membrane. Compared with 1 MHz ultrasonic exposure, the change of the GNP loading amount was not significantly higher upon ultrasonic frequency treatment of 45, 80 or 100 kHz. Therefore, it has been found that an US intensity of 0.25 W cm-2 could facilitate the intra-platelet delivery efficacy of the GNPs without damaging the biological activity. Furthermore, two possible pathways of GNPs entering into platelets upon US treatment are presented: one is the endocytosis/open canalicular system (OCS), and the other is cell membrane permeability enhancement, which is proved by the SEM and TEM results. Finally, the GNP-loaded platelets have been demonstrated as useful probes for photoacoustic imaging (PAI) and dark-field microscopy (DFM)-based imaging, which might allow a wide range of potential applications in diagnostics and therapy of platelet-related diseases.

Fabrication and characterization of protein-phenolic conjugate nanoparticles for co-delivery of curcumin and resveratrol

Curcumin and resveratrol are polyphenols widely used as nutraceuticals because of their strong antioxidant activities and potential health benefits. In this study, the possibility of improving their water-dispersibility, chemical stability, and bioaccessibility using core-shell nanoparticles was examined. The hydrophobic core was fabricated from zein-epigallocatechin gallate conjugates using an antisolvent precipitation method, while the shell was fabricated by coating the core with a biosurfactant (rhamnolipid). The yield, size, morphology, charge (ζ-potential), and loading efficiency of these core-shell nanoparticles were characterized. The nanoparticles formed were anionic spheres with mean diameters <200 nm. Spectroscopic analyses suggested that curcumin and resveratrol were present in an amorphous form in the nanoparticles. The loading efficiencies of nanoparticles containing either curcumin or resveratrol were around 63% and 78%, while they were around 71% and 85% for nanoparticles containing both curcumin and resveratrol, respectively. The nanoparticles protected the two nutraceuticals from degradation while preserving their antioxidant activity. The bioaccessibility for both curcumin and resveratrol was significantly improved when the core-shell nanoparticles were mixed with lipid droplets. This study showed that resveratrol and curcumin could be co-encapsulated in mixed colloidal delivery systems designed to improve their stability and bioaccessibility. These delivery systems may be useful for application in functional foods, supplements, or pharmaceuticals.

Synthesis of biotin‐targeted chitosan/poly (methyl vinyl ether‐ alt ‐maleic acid) copolymeric micelles for delivery of doxorubicin

Biotinylated chitosan/poly(methyl vinyl ether-alt -maleic acid) (PMVEMA) copolymer was synthesised by an amide reaction in two steps. Structural characterisation was performed using 1 HNMR and Fourier transform infra-red (FTIR) spectra. Critical micelle concentration (CMC) of the copolymer was determined by pyrene as a fluorescent probe. Doxorubicin (DOX) was loaded in the micelles by the direct dissolution method. The effects of different variables including type of copolymer, copolymer concentration, stirring rate and stirring time were studied on the physicochemical properties of the micelles including: particle size, zeta potential, release efficiency and loading efficiency of nanoparticles using an irregular factorial design. The in vitro cytotoxicity of DOX-loaded biotin-targeted micelles was studied in HepG2 cells which over express biotin receptors by 3, 5-[dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide assay. The successful synthesis of the biotinylated copolymer of chitosan/PMVEMA was confirmed by FTIR and 1 HNMR. The optimised micelles showed the CMC of 33 μg/ml, particle size of 247 ± 2 nm, zeta potential of +9.46 mV, polydispersity index of 0.22, drug-loading efficiency of 71% and release efficiency of 84.5 ± 1.6%. The synthesised copolymer was not cytotoxic. The cytotoxicity of DOX-loaded in targeted micelles on HepG2 cell line was about 2.2-fold compared with free drug.

Immune Cell-Mediated Biodegradable Theranostic Nanoparticles for Melanoma Targeting and Drug Delivery.

Although tremendous efforts have been made on targeted drug delivery systems, current therapy outcomes still suffer from low circulating time and limited targeting efficiency. The integration of cell-mediated drug delivery and theranostic nanomedicine can potentially improve cancer management in both therapeutic and diagnostic applications. By taking advantage of innate immune cell's ability to target tumor cells, the authors develop a novel drug delivery system by using macrophages as both nanoparticle (NP) carriers and navigators to achieve cancer-specific drug delivery. Theranostic NPs are fabricated from a unique polymer, biodegradable photoluminescent poly (lactic acid) (BPLP-PLA), which possesses strong fluorescence, biodegradability, and cytocompatibility. In order to minimize the toxicity of cancer drugs to immune cells and other healthy cells, an anti-BRAF V600E mutant melanoma specific drug (PLX4032) is loaded into BPLP-PLA nanoparticles. Muramyl tripeptide is also conjugated onto the nanoparticles to improve the nanoparticle loading efficiency. The resulting nanoparticles are internalized within macrophages, which are tracked via the intrinsic fluorescence of BPLP-PLA. Macrophages carrying nanoparticles deliver drugs to melanoma cells via cell-cell binding. Pharmacological studies also indicate that the PLX4032 loaded nanoparticles effectively kill melanoma cells. The "self-powered" immune cell-mediated drug delivery system demonstrates a potentially significant advancement in targeted theranostic cancer nanotechnologies.

Magnetic responsive of paclitaxel delivery system based on SPION and palmitoyl chitosan

Concerns over cancer treatment have largely focused on chemotherapy and its consequent side effects. Utilizing nanocarriers is thought to be a panacea for mitigating the limitations of chemotherapy, and increasing its safety and efficacy. Magnetically driven Paclitaxel delivery systems are among the commonly investigated types of nanocarriers over the last two decades. In this context, we tried to highlight the application of an AC magnetic field and validate its consequential effects on drug delivery pattern and cell death in such nanodevices. So the aim of this study is to develop an appropriate matrix (Palmitoyl chitosan) co-encapsulated with superparamagnetic iron oxide nanoparticles (SPIONs) and anticancer drug, Paclitaxel (PTX) via the nanoprecipitation process. Synthesized nanoparticles were characterized by Dynamic Light Scattering (DLS) and their magnetic properties were investigated by Vibrating Sample Magnetometer (VSM). At initial loading of 10wt% Paclitaxel, the maximum loading efficiency of nanoparticles with and without SPIONs was in the range of 69% and 72.3%, respectively. In addition, in vitro release data revealed that by the application of a magnetic field, release kinetic changed to the magnetic responsive pattern. Encapsulating anticancer drug in a synthesized nanosystem not only increased the amount of drug in cancer cells but also enhanced cell death (MCF-7) due to hyperthermic effects of SPIONs in the presence of an external magnetic field. In summary, these findings indicate that the resultant nanoparticles may serve as a biocompatible and biodegradable carrier for the precise delivery of powerful cytotoxic anticancer agents such as PTX.

Ligand Assisted Stabilization of Fluorescence Nanoparticles; an Insight on the Fluorescence Characteristics, Dispersion Stability and DNA Loading Efficiency of Nanoparticles.

This work reports on the ligand assisted stabilization of Fluospheres® carboxylate modified nanoparticles (FCMNPs), and subsequently investigation on the DNA loading capacity and fluorescence response of the modified particles. The designed fluorescence bioconjugate was characterized with enhanced fluorescence characteristics, good stability and large surface area with high DNA loading efficiency. For comparison purpose, bovine serum albumin (BSA) and polyethylene glycol (PEG) with three different length strands were used as cross linkers to modify the particles, and their DNA loading capacity and fluorescence characteristics were investigated. By comparing the performance of the particles, we found that the most improved fluorescence characteristics, enhanced DNA loading and high dispersion stability were obtained, when employing PEG of long spacer arm length. The designed fluorescence bioconjugate was observed to maintain all its characteristics under varying pH over an extended period of time. These types of bioconjugates are in great demand for fluorescence imaging and in vivo fluorescence biomedical application, especially when most of the as synthesized fluorescence particles cannot withstand to varying in vivo physiological conditions with decreases in fluorescence response and DNA loading efficiency.

Optimization of Self-Assembled Chitosan/Streptokinase Nanoparticles and Evaluation of Their Cytotoxicity and Thrombolytic Activity.

In this study, the enzyme streptokinase (thrombolysis agent) and chitosan (Cs) nanoparticles were prepared by self-assembly. Using experimental design, chitosan concentration, solution pH and stirring time were studied as independent variables to identify their effects on size, polydispersity index (PDI) and loading efficiency of nanoparticles. Results showed that pH and concentration have a direct effect on size. Additionally, minimum PDI was observed at lowest values of concentration and highest values of stirring time. pH-5.6 was also necessary to obtain the smallest PDI and highest loading efficiency values. The model predicted that to obtain maximum loading efficiency and minimum size along with low PDI, optimum values are 0.5 mg/mL, 5.18 and 30 min for the Cs concentration, solution pH and stirring time, respectively. The corresponding mean ± SD values for experimentally prepared nanoparticles were 43 ± 10%, 526 ± 121 nm, 0.3 ± 0.2, respectively. MTT and euglobulin clot lysis assays on the optimized nanoparticles showed that chitosan/streptokinase nanoparticles have slightly toxic effect on human fetal lung fibroblast cells (Mrc-5), compared with chitosan and streptokinase alone as a control. Also, thrombolytic activity of encapsulated streptokinase in nanoparticles is decreased slightly in comparison with free streptokinase. However, the preparation keeps a good potency for use as a thrombolytic agent in vivo.

Preparation and optimization of N-trimethyl-O-carboxymethyl chitosan nanoparticles for delivery of low-molecular-weight heparin

The aim of this study was preparation, optimization and in vitro characterization of nanoparticles composed of 6-[O-carboxymethyl]-[N,N,N-trimethyl] (TMCMC) for oral delivery of low-molecular-weight heparin. The chitosan derivative was synthesized. Nanoparticles were prepared using the polyelectrolyte complexation method. Box–Behnken response surface experimental design methodology was used for optimization of nanoparticles. The morphology of nanoparticles was studied using transmission electron microscopy. In vitro release of enoxaparin from nanoparticles was determined under simulated intestinal fluid. The cytotoxicity of nanoparticles on a Caco-2 cell line was determined, and finally the transport of prepared nanoparticles across Caco-2 cell monolayer was defined. Optimized nanoparticles with proper physico-chemical properties were obtained. The size, zeta potential, poly-dispersity index, entrapment efficiency and loading efficiency of nanoparticles were reported as 235 ± 24.3 nm, +18.6 ± 2.57 mV, 0.230 ± 0.03, 76.4 ± 5.43% and 12.6 ± 1.37%, respectively. Morphological studies revealed spherical nanoparticles with no sign of aggregation. In vitro release studies demonstrated that 93.6 ± 1.17% of enoxaparin released from nanoparticles after 600 min of incubation. MTT cell cytotoxicity studies showed no cytotoxicity at 3 h post-incubation, while the study demonstrated concentration-dependent cytotoxicity after 24 h of exposure. The obtained data had shown that the nanoparticles prepared from trimethylcarboxymethyl chitosan may be considered as a good candidate for oral delivery of enoxaparin.

DESIGN AND EVALUATE ALGINATE NANOPARTICLES AS A PROTEIN DELIVERY SYSTEM

In recent years, encapsulation of drugs and antigens in hydrogels, specifically in calcium alginate particles, is an interesting and practical technique that was developed widespread. It is well known that alginate solution, under proper conditions, can form suitable nanoparticles as a promising carrier system, for vaccine delivery. The aim of this study was to synthesis alginate nanoparticles as protein carrier and to evaluate the influence of various factors on nanoparticles properties. Alginate nanoparticles were prepared by ionic gelation method. Briefly, various concentrations of CaCl2 were added to different concentrations of sodium alginate dropwisly by homogenizing magnetically at 1300 rpm. The effects of homogenization time and (-) rate were investigated on nanoparticle feature. Nanoparticles were characterized for their morphology and size distribution. Evaluation of loading capacity and loading efficiency of nanoparticles were performed by using various concentration of BSA. The concentration of 0.3%w/v sodium alginate and 0.1%w/v CaCl2 solution, homogenization time 45 min and homogenization rate 1300 rpm were observed as suitable condition - to prepare optimized nanoparticles. It can be concluded that the properties of nanoparticles are strongly dependent on the physicochemical conditions. The optimum concentrations of alginate and CaCl2and appropriate condition led to forming desirable nanoparticles that can be used as carrier for drug and vaccine delivery.

In situ synthesis of silver nanoparticles onto cotton fibres modified with plasma treatment and acrylic acid grafting

Silver nanoparticles were synthesised on the modified cotton fibres using an in situ method. Acrylic acid was grafted on the surface of cotton using plasma technology as a means to enhance the loading efficiency of nanoparticles. The loading efficiency of silver nanoparticles into the cotton fabric was examined by an atomic absorption spectrometer. The surface of the fibres was characterised by low-voltage scanning electron microscopy and attenuated total reflection-Fourier transform infrared spectrometry. The cotton fabrics loaded with Ag nanoparticles were examined by thermogravimetric analysis. In addition, the antibacterial activity of loaded samples was determined according to the AATCC test method 147-2004. Grafting of acrylic acid on cotton fibre leads to increase in the loading efficiency of silver nanoparticles and this sample showed the highest antibacterial activity.

A new approach to determine loading efficiency of Leu-enkephalin in poly(isobutylcyanoacrylate) nanoparticles coated with thiolated chitosan

This study is focused on a new approach for the determination of Leu-enkephalin loading efficiency in poly(isobutylcyanoacrylate) nanoparticles coated with depolymerized and thiolated chitosan (Mw 30, 85 and 145 kDa). Nanoparticles were obtained by anionic emulsion polymerization. The aim of this work was to propose a reliable method for the determination of the loading efficiency of Leu-enkephalin in nanoparticles. The amount of Leu-enkephalin contained in nanoparticles was determined after separation of loaded Leu-enkephalin from the dispersing medium using a modern and fast ultrafiltration technique as alternative to ultracentrifugation. The amount of Leu-enkephalin entrapped in nanoparticles was determined after total dissolution of nanoparticles in DMSO. Finally, the method developed in the present work was applied to the determination of the loading efficiency of nanoparticles prepared by two methods. The method consisting in loading nanoparticles with Leu-enkephalin at the same time as the preparation of the nanoparticles yielded higher loading efficiency (from 85 to 92%) than the method based on the adsorption of Leu-enkephalin on preformed nanoparticles (from 62 to 65%).

The characters of self-assembly core/shell nanoparticles of amphiphilic hyperbranched polyethers as drug carriers

The characters of self-assembly core/shell nanoparticles of amphiphilic hyperbranched polyethers (HP-g-PEO) as drug carriers were investigated. The HP-g-PEO consisting of hydrophobic HP-g-PEO core and hydrophilic poly(ethylene glycol) arms was prepared by the cation ring-opening polymerization. A series of HP-g-PEO samples with different degree of branching (DB) were synthesized under various reaction temperatures. Nanoparticles (NP) were obtained by self-assembly of HP-g-PEO in aqueous media. The structure of resulting HP-g-PEO was characterized by IR, 13CNMR and GPC. Dynamic light scattering and transmission electron microscopy were applied to characterize the sizes and size distributions of NP. The results demonstrated that the mean diameters of NP were less than 100 nm, which exhibited uniform spherical formations and narrow size distributions. Using hydrophobic drug Probucol (PRO) as model drug, the particle sizes of drug loaded NP were larger than relative blank NP. The drug loading efficiency (LE) and incorporation efficiency (IE) of these NP were achieved to 35 and 89%, respectively. The in vitro release of PRO from the NP exhibited a sustained release and the cumulative drugs released for more than 600 h. The most important factor to affect drug release was the value of DB of HP-g-PEO. With the DB of HP-g-PEO increasing, the size and size distribution of NP decreased as well as the release rate. However, the small DB was beneficial to the LE of NP. Nanoparticle size and size distribution, LE, IE, and drug release rate were slightly affected by the initial solution concentration of polyethers. The co-incorporated hydrophilic drug had influence slightly on the release of drug from drug loaded NP. The results of in vitro drug release suggested that the core/shell NP performed good controlled release behaviors with potential practice as novelty drug delivery vehicles.

Incorporation and release behavior of hydrophobic drug in functionalized poly( d, l-lactide)-block–poly(ethylene oxide) micelles

The poly(ethylene oxide)–poly(lactide) (PEO–PLA) block copolymers containing a small quantity of carboxylic acid in the PLA block were synthesized. The microscopic characteristics of nanoparticles with carboxylic acid content in the copolymer were analyzed, and the effect of specific interactions between the copolymer and the model drug on the drug loading capacity and the release behavior were investigated systematically. The sizes of nanoparticles prepared by a dialysis method are within the range of 30–40 nm. The nanoparticles prepared from functionalized block copolymers have a very low critical micelle concentration (CMC) value as low as ∼10 −3 mg/ml, which indicates a good stability of the nanoparticles in spite of the presence of carboxylic acid. The drug loading efficiency of nanoparticles dramatically increased when carboxylic acid content was increased in the block copolymer. This result may be attributed to the increase of interactions between the copolymer and the drug. The release rate of the drug was much slower from nanoparticles containing higher amounts of carboxylic acid in the copolymer, which might be associated with the enhanced interaction between the carboxylic group of copolymers and the drug. These experimental results suggest that the nanoparticles prepared from functionalized PEO–PLA block copolymers could be a good candidate for an injectable drug delivery carrier.