Poly Glycol Research Articles

Characterization of PLGA versus PEG-PLGA intracochlear drug delivery implants: Degradation kinetics, morphological changes, and pH alterations

Drug delivery to the inner ear presents a unique challenge due to the complex inner ear anatomy and its tight physiological barriers. This study investigates the degradation behavior of intracochlear drug delivery implants (IDDI) composed of dexamethasone and poly(lactic-co-glycolic acid) (PLGA) or polyethylene glycol–poly(lactic-co-glycolic acid) (PEG-PLGA), respectively. IDDI were incubated in artificial perilymph and implants' degradation kinetics, morphological changes, water uptake behavior, and pH alterations were assessed. Microscopy revealed significant changes in appearance, with PLGA IDDI exhibiting rapid expansion, reaching up to 183 % in diameter and 185 % in length. PEG-PLGA implants showed gradual expansion, reaching a maximum of 178 % in diameter and 144 % in length. Despite these morphological changes, the IDDIs could still be applicable in terms of cochlear dimensions in combination with cochlear implants (CI) in humans or in a domestic pig animal model. Scanning electron microscopy analysis demonstrated surface alterations of PLGA implants, while PEG-PLGA implants remained shape-stable. Gravimetric analysis and gel permeation chromatography revealed distinct degradation profiles, with PLGA implants displaying rapid water uptake and mass loss, while PEG-PLGA implants showed delayed water uptake and minimal mass reduction. pH measurements using the pH-sensitive fluorescent dye SNARF™-1 showed initial pH reduction in artificial perilymph for PLGA implants while PEG-PLGA implants maintained pH stability.

Towards the optimization of drug delivery to the cochlear apex: Influence of polymer and drug selection in biodegradable intracochlear implants

There is growing need for new drug delivery systems for intracochlear application of drugs to effectively treat inner ear disorders. In this study, we describe the development and characterization of biodegradable, triamcinolone-loaded implants based on poly(lactic-co-glycolic acid) (PLGA) and polyethylene glycol–poly(lactic-co-glycolic acid) (PEG-PLGA) respectively, prepared by hot-melt extrusion. PEG 1500 was used as a plasticizer to improve flexibility and accelerate drug release. The sterilization process was performed by electron beam irradiation, resulting in minimal but acceptable polymer degradation for PEG-PLGA implants. The implants have been characterized by texture analysis, differential scanning calorimetry and X-ray powder diffraction. Compared to PLGA implants, PEG-PLGA implants offer similar flexibility but with improved mechanical stability, which will ease the handling and intracochlear application. A controlled release over three months was observed for dexamethasone and triamcinolone extrudates (drug load of 10%) with similar release profiles for both drugs. PEG-PLGA implants showed an initial slow release rate over several days regardless of the amount of PEG added. Mathematical simulations of the pharmacokinetics of the inner ear based on the in vitro release kinetics indicate a complete distribution of triamcinolone in the whole human scala tympani, which underlines the high potential of the developed formulation.

Evaluation of the effect of guanabenz-loaded nanoparticles on chronic toxoplasmosis in mice

Chronic toxoplasmosis which is positively correlated with many neuropsychiatric problems has no curative treatment till now; due to the resistant tissue cysts especially in the brain. In search of an effective treatment, guanabenz-loaded polyethylene glycol poly lactic-co-glycolic acid (PEG-PLGA) nanoparticles was evaluated against chronic experimental toxoplasmosis. For this purpose, each mouse was infected with 10 cysts of Toxoplasma gondii (ME 49 strain). Treated mice received either guanabenz alone (5 mg/kg/day) in subgroup IIa or guanabenz-loaded nanoparticles by full dose in subgroup IIb or guanabenz-loaded nanoparticles by the half dose (2.5 mg/kg/day) in subgroup IIc. Subgroup Ie was treated by pyrimethamine and sulfadiazine. The treatment started on day 25 post-infection for 19 successive days. Then Parasitological, histopathological, immunohistochemical, immunological and ultrastructural morphological studies were performed. The results showed that: subgroup IIb showed the highest statistically significant reduction in the neuroinflammation and brain tissue cysts (77%) with a significant higher efficacy in comparison with pyrimethamine and sulfadiazine and showed the highest level of IFN-γ, while the lowest level was in subgroup IIa. All group II mice showed similar changes of depression and compression of the wall of the cyst. This is marked in subgroup IIb with release of crescent shaped bradyzoite outside the cyst. PEG-PLGA nanoparticles had no toxic effect on the liver or the kidney of the mice. It could be concluded that guanabenz-loaded PEG-PLGA nanoparticles could be promising and safe for treatment of chronic toxoplasmosis.

MPEG-PCL Nanoparticles as New Carriers for Delivery of a Prostae Cancer Drug Fluamide

The present work was aimed to prepare and evaluate Flutamide loaded methoxy poly (ethylene glycol) poly caprolactone (mPEG–PCL) nanoparticles for targeted delivery to the prostate cancer. The nanoparticles (NPs) were prepared by 23 factorial design and nanoprecipitation method. Various trials were evaluated for surface morphology, particle size and zeta potential. The influences of three formulation excipients such as polymer, stabilizer and organic phase volume on the characterization of NPs were investigated. The results of fourier transform infrared (FTIR) studies were indicated no interaction between the drug and polymer. The particle size varied from 79.2 to 89.1 nm and zeta potential value was found to be - 41.5 mv. The surface morphology of NPs was observed using scanning electron microscopy (SEM) and understands the arrangement and orientation of NPs to determine its behavior and stability. Flutamide loaded mPEG–PCL nanoparticle is a potential new carrier system for treatment of prostate cancer, which may overcome the problems associated with conventional formulations such as tablets.

Preparation of a novel polyurethane network based on PPG–PGN–PPG: investigation of the effect of plasticizers on its properties

In this research to improve the thermal and mechanical properties of polyglycidyl nitrate (PGN)-based energetic polyurethane network was used a novel flexible chain triblock copolymer based on polypropylene glycol–poly glycidyl nitrate–polypropylene glycol (PPG–PGN–PPG). Energetic polyurethane was prepared by curing of the triblock copolymer with different curing agents (TDI, IPDI, N100, IPDI/N100) and different NCO/OH ratios. To evaluate the effect of plasticizer on the thermo-mechanical properties of the polyurethane, the compatibility of copolymer with three energetic plasticizers, including n‐butyl nitroxyethyl nitramine (BuNENA), trimethylol ethane trinitrate (TMETN), and 1,2,4-butanetriol trinitrate (BTTN) was studied using the swelling test and thermal analysis. The results indicate that BuNENA is more compatible with this copolymer than other plasticizers. The mechanical properties effect of the BuNENA plasticizer on the polyurethane network was investigated using dynamic mechanical analysis as well as the tensile test. The IPDI/N100 curing agents-polyurethane mixture, demonstrated appropriate mechanical properties (0.35 MPa stress and 70% elongation) that make it a suitable binder system comparison with pure PGN (unstable and de-cured). Also the mechanical properties of the prepared polyurethane containing 15 wt% BuNENA showed 0.17 MPa stress and 98% elongation.

A Facile Fabrication Route of Poly(Ethylene Glycol Phenyl Ether Acrylate) Photopolymers with Efficient Optical Response for Holographic Storage

A series of photopolymers based on ethylene glycol phenyl ethyl arylate (EGPEA) monomers and poly(methyl methacrylate) (PMMA) matrix with varying initiator concentrations and sample thicknesses have been synthesized and their optical performance characterized in this study. The advantages of lowering the initiator concentration, including a rather short initiation time within a few seconds; a sharp rising optical response; and a stable saturated diffraction efficiency are demonstrated. The variation in the diffraction efficiency and response time with the exposure energy under various sample thickness and initiator concentrations is examined; a diffraction efficiency as high as 80% and a relatively short response time of 12–39 s are attainable. The dependence of the normalized optical parameter “sensitivity” on the exposure time is depicted, and the peak value of S ranges vastly from about 0.2 to 1.2 × 104 cm/J within a period of 15 s or so, with a maximum value of nearly 1.2 × 104. Favorable evidence of low initiator concentration can further be found when the dependence of the saturated diffraction efficiency with the exposure energy is examined. The data from this study using a low initiator concentration cover a range of exposure energy from 100 to 800 mJ/cm2 and a saturated diffraction efficiency from about 15% to 80%. The successful image reconstruction of 6-membered-ring metal nuts on a hologram based on this EGPEA/PMMA photopolymer system using a reflective holographic recording setup is demonstrated to verify its applicability to holographic storage.

Morphological transition of amphiphilic block copolymer/PEGylated phospholipid complexes induced by the dynamic subtle balance interactions in the self-assembled aggregates

Abstract Recently, there has been an increasing interest in the control of morphological transition of block copolymer aggregates. Here, we report how to control the morphological transition of methoxy polyethylene glycol–poly(d,l-lactic acid) (PDLLA–MPEG) by adding 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)] (DSPE–PEG). In the aggregates formed by dialyzing DSPE–PEG/PDLLA–MPEG mixed solutions against water, the two hydrophobic fatty acid tails of DSPE–PEG will preferentially anchor to the hydrophobic segment end of PDLLA–MPEG by interdigitating between these two tails and PDLLA segments. Consequently, DSPE–PEG and PDLLA–MPEG will form “ABA” temporary supra-amphiphiles in which A represents a poly(ethylene glycol) (PEG) chain segment and B is a mixed hydrophobic segment composed of PDLLA and DSPE segments; the repulsive force derived from the PEG segments of DSPE–PEG can affect the stability of “ABA” temporary supra-amphiphiles. Our results show that the dynamic subtle balance between the number of “ABA” temporary supra-amphiphiles formed and the strength of repulsive force between the PEG segments of DSPE–PEG drives the morphological structure of DSPE–PEG/PDLLA–MPEG aggregates to change from micelles to vesicles, then to semi-vesicles and finally to mixed micelles, with increasing DSPE–PEG additions.

Enhancement of Loading Efficiency by Coloading of Doxorubicin and Quercetin in Thermoresponsive Polymeric Micelles.

Chemotherapy faces challenges, including poor aqueous solubility of the drugs, and cardiotoxicity. Micellar drug delivery systems (DDS) are used to encapsulate anticancer drugs for better therapeutic effects, however, with poor loading content. Herein, we synthesized a micellar DDS using γ-benzyloxy substituted poly(ε-caprolactone) as the hydrophobic block and coloaded anticancer doxorubicin (Dox) and antioxidant quercetin (Que). γ-Substituted oligo(ethylene) glycol (OEG) poly(ε-caprolactone)s were used as hydrophilic blocks to make the polymers thermoresponsive. Variation of the OEG chain allowed the tunability of the lower critical solution temperature. Moreover, drug loading and release were studied. Thermodynamic stability, size, and morphology were determined by fluorescence measurements, dynamic light scattering, and transmission electron microscopy. Combination loading demonstrated improved loading of Dox and Que. Biological studies were performed using HepG2 human liver cancer and H9c2 rat heart cells. The use of biodegradable, biocompatible, and thermoresponsive polymers along with the coloading approach is a good strategy in developing DDSs.

Effect of molecular weight of polyethylene glycol on crystallization behaviors, thermal properties and tensile performance of polylactic acid stereocomplexes

In this work, the poly(d-lactic acid)–polyethylene glycol–poly(d-lactic acid) (PDLA–PEG–PDLA) triblock copolymer as a novel modification agent was incorporated into poly(l-lactic acid) (PLLA) to improve the thermal and mechanical properties of PLLA. The influences of molecular weight of PEG in the triblock copolymer on the structure, crystallization behaviors, heat resistance and tensile properties of PDLA–PEG–PDLA/PLLA blends were investigated by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), polarized optical microscopy (POM), thermogravimetric analysis (TGA) and tensile testing. The results from FTIR, XRD and DSC confirm the formation of a polylactide stereocomplex in the PLLA blends. The structure and properties of the stereocomplex crystals are different from those of pure PLLA. The melting temperature (Tm) of the stereocrystal is near 200 °C, which is significantly higher than that of the homogeneous crystal of PLLA. The effect of molecular weight of PEG on the crystal morphology of PLLA blends is also obvious. The improvement of tensile properties for PLLA blends is attributed to the crystal morphological features, which will potentially enhance the utility of the PLLA based polymer.

Synthesis, thermal stability and kinetic decomposition of triblock copolymer polypropylene glycol–poly glycidyl nitrate–polypropylene glycol (PPG–PGN–PPG)

An energetic triblock copolymer PPG–PGN–PPG (Mn = 1886 g mol−1) was synthesized for the first time by cationic ring-opening polymerization of propylene oxide with low molecular weight poly glycidyl nitrate (PGN) (Mn = 1061 g mol−1) as a macroinitiator, in the presence of boron trifluoride etherate (BF3·OEt2) as the catalyst. The product obtained in high yield was characterized by FTIR, gel permeation chromatography and 1H and 13C NMR spectroscopy. The thermal properties of the triblock copolymer were characterized by differential scanning calorimeter (DSC). The result approved that the glass transition temperature of the triblock copolymer (Tg = − 58 °C) is lower than PGN (Tg = − 35 °C); also, it was more stable than that of PGN. The effect of heating rates (10, 20, 30 and 40 °C min−1) on the decomposition of the copolymer was evaluated. The decomposition temperature of this compound increased as the heating rate increased. The kinetic parameters such as activation energy and frequency factor for the thermal decomposition of the triblock copolymer were obtained from the DSC and DTG data by non-isothermal methods proposed by the ASTM E696, Flynn–Wall–Ozawa (FWO) and Kissinger methods. The values by the FWO method are in good agreement with ASTM and Kissinger methods.

Poly(propylene ether carbonate)-Based Di- and Tri-Block Copolymers: Synthesis and Chromatographic Characterization

In this study, ring-opening polymerization (ROP) of propylene carbonate (PC) is conducted for synthesis of novel amphiphilic di- and tri-block copolymers containing poly(ethylene oxide) as hydrophilic with poly(propylene ether-carbonate (PPEC) as a hydrophobic block. A series of di- and tri-block copolymers is synthesized, by using macro-initiators [polyethylene glycol monomethyl ethers and poly(ethylene glycol)s] of different molar masses, while systematically varying monomer to macro-initiator ratio. The synthesized block copolymers are characterized by size exclusion chromatography, for augmentation in the molar mass, NMR for average chemical composition while liquid chromatography at critical conditions, is used for comparison of individual block lengths alongside purity of block copolymers, with regard to presence of homopolymers of both types. Chromatographic critical conditions of the polymer synthesized by ROP of PC, PPEC, are reported for the first time. Established chromatographic critical conditions of PEG and PPEC, successfully tracked presence of homopolymers of both types, with fair comparison of individual block lengths of the block copolymers synthesized by the same macro-initiator.

EHD friction properties of ISO VG 320 gear oils with smooth and rough surfaces

The elastohydrodynamic (EHD) friction properties of seven ISO VG 320 gear oils including three polyalphaolefins (PAOs), three polyglycols (PG) and a mineral oil have been investigated in rolling/sliding conditions at six different temperatures and three roughnesses. Film thickness, Stribeck and traction curves have been generated using a ball-on-disc tribometer. Film thickness results are in agreement with previous work that it is primarily controlled by pressure-viscosity coefficient and viscosity of lubricants. The results with smooth surface show that all oils experience significant shear heating leading to friction reduction at higher strain rates or lambda ratios but only PGs reach limiting friction whereas mineral oil and PAOs do not. Friction curves obtained at different temperatures and roughnesses enable simulating an extensive range of lubrication regimes and allow isothermal friction correction for shear heating. Stribeck curves with rough surfaces show an increase in friction in the lambda range of 0.5–3.5, where asperity separation varies from partial to full–indicating that roughness effects can be expected even under full film condition. This increase in friction is attributed to formation of a micro-EHD region, and is seen only with mineral oil and PAOs whereas not with PGs. The results also highlight how EHD friction properties of different family of fluids could be influenced by roughness effects, and the possible mechanisms are discussed.

Cells integration onto scaffolds prepared from polyester based polymers – importance of polymer thermal properties in addition to hydrophilicity

Three-dimensional (3D) scaffolds represent valuable tools for biological studies and tissue engineering applications. They offer better biological environment that better mimic 3 D dynamic in vivo conditions compared with conventional bidimentional (2D) cell culture systems. The integration of cells within the scaffolds is, however, dependent on their properties. In the present study, porous scaffolds were prepared from poly lactide (PLA), poly lactide polyethylene glycol copolymer (PLA-PEG) and poly lactide-co-glycolide – polyethylene glycol copolymer (PLGA-PEG) using porogen leaching method with NaCl particles as porogen. The three scaffolds were prepared with identical conditions (concentration, dimensions, porogen weight fraction and particle size) in order to evaluate the impact of polymer composition and properties on scaffold characteristics (internal architecture and pores distribution), as well as fibroblasts integration and proliferation within the scaffold 3 D network. The impact of hydrophilicity, water uptake and protein adsorption are discussed. The data shows that amorphous polymers, which have glass transition temperature close to cell culture temperature, may be advantageous for scaffold construction and cell integration. This fact needs to be considered when interpreting data of cell interaction with scaffolds obtained using amorphous polymers developed for 3 D cell culture and tissue engineering applications.

Curcumin mediated down-regulation of αV β3 integrin and up-regulation of pyruvate dehydrogenase kinase 4 (PDK4) in Erlotinib resistant SW480 colon cancer cells.

Erlotinib is a potent, selective, and orally active inhibitor of the epidermal growth factor receptor, but the development of erlotinib resistance during chemotherapy can lead to treatment failure. To shed light on the erlotinib-resistant pathway, this study investigated the effect of combination therapy using curcumin- and erlotinib-loaded nanoparticles on the expression of αv β3 integrin and pyruvate dehydrogenase kinase 4 (PDK4) in an erlotinib-resistant SW480 colon cancer cell line. An erlotinib-resistant SW480 colon cancer cell line was produced by long-term exposure to erlotinib. Curcumin-loaded Methoxy poly ethylene glycol Poly caprolactone (cur/mPEG-PCL) and erlotinib-loaded mPEG-PCL (erl/mPEG-PCL) micelles were provided using a single step nanoprecipitation method and used as combination therapy of resistant SW480 cancer cells. After that, gene expression levels of PDK4, αv, and β3 mRNA were determined by the semiquantitative reverse transcription-polymerase chain reaction. Protein levels of whole αv β3 integrin were evaluated using the enzyme-linked immunosorbent assay method. In SW480 cell line, the IC50 of nonresistant and resistant cells was 87.6±1.2nM and 19.1±0.14μM, for erlotinib and it was about 21.8 and 30μM for curcumin, respectively. Although PDK4 expression was not significantly different in resistant and nonresistant cells, its expression was up regulated (1.4 fold) in resistant cells by a combination therapy of cur/mPEG-PCL at a dose of 3μM and erl/mPEG-PCL at a dose of 5μM. β3 mRNA and the protein level of whole αv β3 integrin was significantly higher in resistant SW480 cells as compared with those in nonresistant cells. In terms of treatment, a combination of 6-μM cur/mPEG-PCL and 5-μM erl/mPEG-PCL down regulated β3 gene expression 6.6-fold in resistant cells as compared with nonresistant cells. At the protein level, a combination of 3-μM-cur/mPEG-PCL and 10-μM erl/mPEG-PCL reduced αv β3 protein in resistant cells. The results indicated that combination therapy using cur/mPEG-PCL and erl/mPEG-PCL could decrease αv β3 integrin expression and increase PDK4 gene expression in resistant colon cancer cells, which may have effects on drug resistance signaling pathways.

SYNTHESIS OF AMINE-CONTAINING POLYMERIC MICROSPHERES BY SEED COPOLYMERIZATION FOR APPLICATIONS IN BIOTECHNOLOGY

This paper presents the results of studies of seed copolymerization of glycidyl methacrylate with ethylene glycol poly(glycidyl methacrylate) on seed particles in order to obtain partially crosslinked polymer microspheres with a diameter of about 3.5 microns for use in immunochemical reactions, as carriers of bioligands. The physico-chemical properties of polymeric microspheres obtained under different conditions were studied by the following methods: the diameters of the particles - by electron scanning and light microscopy; the wetting angle - bу the method of "lying droplets"; the sedimentation velocity - by the macromethod in a capillary tube by the movement of the (polymer slurry)/water phase boundary (buffer solution); the zeta-potential - by dynamic light scattering. Having studied the physical-chemical properties of all polymer slurries we concluded that the optimal particles to create on the basis of their diagnostic test systems with high sensitivity working on the principle of latex agglutination reaction are poly(glycidyl methacrylate) particles with equal percentage of glycidyl methacrylate and ethylene glycol dimethacrylate aminated with hexamethylendiamine in the environment of n-propanol, because they have a sufficient number of amino groups and do not lose their sedimentation properties after all stages of the synthesis.

Polyethylene glycol-poly(ε-benzyloxycarbonyl-l-lysine)-conjugated VEGF siRNA for antiangiogenic gene therapy in hepatocellular carcinoma.

A polyethylene glycol–poly(ε-benzyloxycarbonyl-l-lysine) (PEG-SS-PLL) block copolymer based on a disulfide-linked, novel biodegradable catiomer bearing a PEG-sheddable shell was developed to avoid “PEG dilemma” in nanoparticle intracellular tracking of PEG-PLL where PEG was nondegradable. However, PEG-SS-PLL catiomers have not been used to deliver small interfering VEGF RNA (siVEGF) in antiangiogenesis gene therapy. In this study, we aimed to investigate whether this novel biodegradable catiomer can deliver siVEGF into cancer cells and at the same time have an antitumor effect in a xenograft mouse model. It was found that PEG-SS-PLL efficiently delivered siVEGF with negligible cytotoxicity, and significantly decreased the expression of VEGF at both the messenger-RNA and protein levels both in vitro and in vivo, and thus tumor growth was inhibited. Our findings demonstrated that PEG-SS-PLL/siVEGF could potentially be applied to antiangiogenesis gene therapy for hepatocellular carcinoma.

Preparation and Performance of Poly(D,L-lactic acid)–Polyethylene Glycol–Poly(D,L-lactic acid) Electrospun Fibrous Membranes for Drug Release.

In this study, poly(D,L-lactic acid)–polyethylene glycol–poly(D,L-lactic acid), hereafter referred to as PDLLA–PEG–PDLLA, triblock copolymer membranes were prepared by electrospinning. Scanning electron microscopy images revealed the morphology of the microfibers, which had a diameter ranging from 300 to 900 nm. Fourier transform infrared spectroscopy was employed for structural analysis of the PDLLA–PEG–PDLLA/florfenicol (FF) membranes, which exhibited three absorption peaks at 3455, 1684, and 1533 cm−1, respectively, indicating that the triblock copolymer and FF are very well blended in the composite membranes. Differential scanning calorimetry revealed that weak interaction possibly decreased the activity of the segment and elevated the T g from 43 °C to 46 °C. From the in vitro dissolution tests, PDLLA as a biodegradable and biocompatible polymer can improve the solubility of FF. The rate of drug release increased with increasing PEG proportion. Furthermore, tensile and nanoindentation tests demonstrated that nanofibers exhibit mechanical properties such as tensile stress (700–2800 KPa), strain (40–120%), and good toughness (0.28–0.98 GPa). In conclusion, PDLLA–PEG–PDLLA nanofibers as a carrier improve the solubility of FF and control drug release.

Mineral-substituted hydroxyapatite reinforced poly(raffinose-citric acid)–polyethylene glycol nanocomposite enhances osteogenic differentiation and induces ectopic bone formation

Progress of biomimetic mineral-substituted hydroxyapatite reinforced poly(raffinose-citric acid)–polyethylene glycol–poly(raffinose-citric acid) for prospective ectopic bone formation.

Preparation of the Sm3+-Doped Magnetic Nanoparticles via Microwave-Assisted Polyol Synthesis

Sm3+-doped magnetic nanoparticles (NPs) were prepared via microwave-assisted polyol synthesis in ethylene glycol, poly(ethylene glycol) and mixed ethylene glycol—poly(ethylene glycol) solutions. In present work, the effects of organic solvent composition on particle size, particle size distribution, extent of agglomeration, and samarium content in prepared NPs were studied. The synthesized NPs were characterized by several techniques as follows: X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetry (TGA) and X-Ray fluorescence (XRF) analysis. XRD and TEM results showed formation of ~6.0–17.9 nm NPs having different microstructure characteristics (average particle size, particle size distribution, and agglomeration). The TGA analysis indicated the presence of organic components on the surface of NPs. Cytotoxic activity of the prepared magnetic NPs towards HeLa cells was evaluated by using standard live/dead assay in comparison to a control solution. It was shown that prepared magnetic NPs are characterized by low toxicity that makes possible their use for biomedical applications.

Photodynamic therapy of tumors with pyropheophorbide-a-loaded polyethylene glycol-poly(lactic-co-glycolic acid) nanoparticles.

Photodynamic therapy (PDT) has many advantages in treating cancers, but the lack of ideal photosensitizers continues to be a major limitation restricting the clinical utility of PDT. This study aimed to overcome this obstacle by generating pyropheophorbide-a-loaded polyethylene glycol–poly(lactic-co-glycolic acid) nanoparticles (NPs) for efficient tumor-targeted PDT. The fabricated NPs were efficiently internalized in the mitochondrion by cancer cells, and they efficiently killed cancer cells in a dose-dependent manner when activated with light. Systemically delivered NPs were highly enriched in tumor sites, and completely ablated the tumors in a xenograft KB tumor mouse model when illuminated with 680 nm light (156 mW/cm2, 10 minutes). The results suggested that this tumor-specific NP-delivery system for pyropheophorbide-a has the potential to be used in tumor-targeted PDT.