Cascade Hydroxyl Radical-Generating and Ferroptosis-Inducing Nanofiber System for the Therapy of Oral Squamous Cell Carcinoma.

Nanofiber (NF) membrane systems that can provide cascade catalytic reaction and ferroptosis induction were developed for oral cancer therapy. Glucose oxidase (GOx) and aminoferrocene (AF) were introduced into the NF system for glucose deprivation/H2O2 generation and OH radical generation, respectively. GOx offers starvation therapy and AF (including iron) provides chemodynamic therapy/ferroptosis for combating oral cancer. GOx (water-soluble) and AF (poorly water-soluble) molecules were successfully entrapped in the NF membrane via an electrospinning process. GOx and AF were incorporated into the polyvinyl alcohol (PVA)-based NF, resulting in PVA/GOx/AF NF with fast disintegration and immediate drug-release properties. In oral squamous cell carcinoma (YD-9 cells), the PVA/GOx/AF NF group exhibited higher cytotoxicity, antiproliferation potential, cellular ROS level, apoptosis induction, lipid ROS level, and malondialdehyde level compared to the other NF groups. The electrospun PVA/GOx/AF NF can be directly applied to oral cancer without causing pain, offering starvation/chemodynamic therapy and ferroptosis induction.

Cuproptosis-Inducible Chemotherapeutic/Cascade Catalytic Reactor System for Combating with Breast Cancer.

Cascade hydroxyl radical generating hydrogel reactor structures including a chemotherapeutic agent are invented for multiple treatment of breast cancer. Glucose oxidase (GOx) and cupric sulfate (Cu) are introduced for transforming accumulated glucose (in cancer cells) to hydroxyl radicals for starvation/chemodynamic therapy. Cu may also suppress cancer cell growth via cuproptosis-mediated cell death. Berberine hydrochloride (BER) is engaged as a chemotherapeutic agent in the hydrogel reactor for combining with starvation/chemodynamic/cuproptosis therapeutic modalities. Moreover, Cu is participated as a gel crosslinker by coordinating with catechol groups in hyaluronic acid-dopamine (HD) polymer. Controlling viscoelasticity of hydrogel reactor can extend the retention time following local injection and provide sustained drug release patterns. Low biodegradation rate of designed HD/BER/GOx/Cu hydrogel can reduce dosing frequency in local cancer therapy and avoid invasiveness-related inconveniences. Especially, it is anticipated that HD/BER/GOx/Cu hydrogel system can be applied for reducing size of breast cancer prior to surgery as well as tumor growth suppression in clinical application.

Hydrogel design to overcome thermal resistance and ROS detoxification in photothermal and photodynamic therapy of cancer.

Responsive heat resistance (by heat shock protein upregulation) and spontaneous reactive oxygen species (ROS) detoxification have been regarded as the major obstacles for photothermal/photodynamic therapy of cancer. To overcome the thermal resistance and improve ROS susceptibility in breast cancer therapy, Au ion-crosslinked hydrogels including indocyanine green (ICG) and polyphenol are devised. Au ion has been introduced for gel crosslinking (by catechol-Au3+ coordination), cellular glutathione depletion, and O2 production from cellular H2O2. ICG can generate singlet oxygen from O2 (for photodynamic therapy) and induce hyperthermia (for photothermal therapy) under the near-infrared laser exposure. (-)-Epigallocatechin gallate downregulates heat shock protein to overcome heat resistance during hyperthermia and exerts multiple anticancer functions in spite of its ironical antioxidant features. Those molecules are concinnously engaged in the hydrogel structure to offer fast gel transformation, syringe injection, self-restoration, and rheological tuning for augmented photo/chemotherapy of cancer. Intratumoral injection of multifunctional hydrogel efficiently suppressed the growth of primary breast cancer and completely eliminated the residual tumor mass. Proposed hydrogel system can be applied to tumor size reduction prior to surgery of breast cancer and the complete remission after its surgery.

Nanorod/nanodisk-integrated liquid crystalline systems for starvation, chemodynamic, and photothermal therapy of cancer.

Indocyanine green (ICG), glucose oxidase (GOx), and copper(II) sulfate (Cu)-installed hybrid gel based on organic nanorod (cellulose nanocrystal [CNC]) and inorganic nanodisk (Laponite [LAP]) was developed to perform a combination of starvation therapy (ST), chemodynamic therapy (CDT), and photothermal therapy (PTT) for localized cancers. A hybrid CNC/LAP network with a nematic phase was designed to enable instant gelation, controlled viscoelasticity, syringe injectability, and longer in vivo retention. Moreover, ICG was introduced into the CNC/LAP gel system to induce hyperthermia of tumor tissue, amplifying the CDT effect; GOx was used for glucose deprivation (related to the Warburg effect); and Cu was introduced for hydroxyl radical generation (based on Fenton-like chemistry) and cellular glutathione (GSH) degradation in cancer cells. The ICG/GOx/Cu-installed CNC/LAP gel in combination with near-infrared (NIR) laser realized improved antiproliferation, cellular reactive oxygen species (ROS) generation, cellular GSH degradation, and apoptosis induction in colorectal cancer (CT-26) cells. In addition, local injection of the CNC/ICG/GOx/Cu/LAP gel into the implanted CT-26 tumor while irradiating it with NIR laser provided strong tumor growth suppression effects. In conclusion, the designed hybrid nanorod/nanodisk gel network can be efficiently applied to the local PTT/ST/CDT of cancer cells.

Alum-tuned hyaluronic acid-based hydrogel with immune checkpoint inhibition for immunophoto therapy of cancer.

Alum-crosslinked hyaluronic acid-dopamine (HD) hydrogel containing indocyanine green (ICG) with anti-programmed cell death-1 (PD-1) antibody (Ab) administration was developed for immunophoto therapy of cancer. Alum modulates the rheological characteristics of hydrogel for enabling syringe injection, shear-thinning feature, and slower biodegradation. In addition, alum in HD-based hydrogel provided CD8+ T cell-mediated immune responses for cancer therapy. ICG in the hydrogel under near-infrared (NIR) light exposure may induce hyperthermia and generate singlet oxygen for selective cancer cell killing. HD/alum/ICG hydrogel injection with NIR laser irradiation elevated PD-1 level in CD8+ T cells. Administration of PD-1 Ab aiming at highly expressed PD-1 in T cells may amplify the anticancer efficacies of HD/alum/ICG hydrogel along with NIR laser. HD/alum/ICG hydrogel with NIR light may have both CD8+ T cell-linked immune responses and ICG-related photodynamic/photothermal effects. Additional injection of immune checkpoint inhibitor can ultimately suppress primary and distant tumor growth by combination with those therapeutic actions.

Manganese Sulfate Nanocomposites Fabricated by Hot-Melt Extrusion for Chemodynamic Therapy of Colorectal Cancer.

The development of metal salts-based nanocomposites is highly desired for the Fenton or Fenton-like reaction-based chemodynamic therapy of cancer. Manganese sulfate (MnSO4)-dispersed nanoparticles (NPs) were fabricated with a hot-melt extrusion (HME) system for the chemodynamic therapy of colorectal cancer in this study. MnSO4 was homogeneously distributed in polyethylene glycol (PEG) 6000 (as a hydrophilic polymer) with the aid of surfactants (Span 80 and Tween 80) by HME processing. Nano-size distribution was achieved after dispersing the pulverized extrudate of MnSO4-based composite in the aqueous media. The distribution of MnSO4 in HME extrudate and the interactions between MnSO4 and pharmaceutical additives were elucidated by Fourier-transform infrared, X-ray diffractometry, X-ray photoelectron spectroscopy, and scanning electron microscopy analyses. Hydroxyl radical generation efficiency by the Fenton-like chemistry capability of Mn2+ ion was also confirmed by catalytic assays. By using the intrinsic H2O2 in cancer cells, MnSO4 NPs provided an elevated cellular reactive oxygen species level, apoptosis induction capability, and antiproliferation efficiency. The designed HME-processed MnSO4 formulation can be efficiently used for the chemodynamic therapy of colorectal cancer.

Donepezil hydrochloride-reinforced cellulose nanocrystal-aggregated gel structure for long-acting drug delivery.

A donepezil hydrochloride (DPZ)-reinforced cellulose nanocrystal (CNC) hydrogel structure with pH control was developed for sustained drug delivery through subcutaneous injection. In the present study, an aggregated CNC gel was fabricated by reducing the electrostatic repulsion between CNC particles by incorporating DPZ and adjusting the pH value to 7.7. The crosslinked CNC/DPZ (cCNC/DPZ) gel exhibited immediate gelation, injection capability through a single syringe, improved viscoelasticity, and shear-thinning properties. Interactions between the CNCs and DPZ and pH regulation were assessed using several solid-state studies, and a sustained release profile of the DPZ from the cCNC/DPZ gel was also observed. In the pharmacokinetic study, a higher half-life and mean residence time and lower maximum drug concentration values were obtained in the cCNC/DPZ group than in the DPZ solution and CNC/DPZ groups after subcutaneous injection. Drug salt form-incorporated and pH-controlled CNC hydrogel systems can be safely applied to the subcutaneous delivery of DPZ.

Ferrocene and glucose oxidase-installed multifunctional hydrogel reactors for local cancer therapy.

A hyaluronic acid (HA)-based one-pot hydrogel reactor with single syringe injection and immediate gelation was developed for starvation therapy (ST), chemodynamic therapy (CDT), ferroptosis, and photothermal therapy (PTT) against breast cancer. A rheologically tuned hydrogel network, composed of HA-phenylboronic acid (HP) and HA-dopamine (HD), was designed by introducing a boronate ester linkage (phenylboronic acid-dopamine interaction) and polydopamine bond (pH control). Ferrocene (Fc)-conjugated HP (Fc-HP) was synthesized to achieve ferroptosis, Fenton reaction-involved toxic hydroxyl radical (•OH) generation, and photothermal ablation in cancer therapy. Glucose oxidase (GOx) was entrapped in the pH-modulated Fc-HP (Fc-HP°)/HD hydrogel network for converting intracellular glucose to H2O2 to enable its own supply. The GOx/Fc combination-installed hydrogel reactor system can provide sustained ST/CDT/PTT functions along with ferroptosis. Injection of Fc-HP°/HD/GOx hydrogel with single-syringe injectability, shear-thinning feature, and self-healing capability offered a slow biodegradation rate and high safety profiles. Peritumorally injected Fc-HP°/HD/GOx hydrogel also efficiently suppressed the growth of breast cancer based on multifunctional therapeutic approaches with reduced dosing frequency. Hyperthermia induced by near-infrared (NIR) laser absorption may amplify the therapeutic effects of free radicals. It is expected that this Fc-HP°/HD/GOx hydrogel system can be applied to local cancer therapy with high efficacy and safety profiles.

Gas generating microspheres for immediate release of Hsp90 inhibitor aiming at postembolization hypoxia in transarterial chemoembolization therapy of hepatocellular carcinoma.

CO2 gas generating poly(lactic-co-glycolic acid) (PLGA) microsphere (MS) was designed for rapid release of tanespimycin (17-AAG) in transarterial chemoembolization (TACE) treatment of hepatocellular carcinoma (HCC). As poorly water-soluble drug is generally released from PLGA MS in a sustained manner, the drug release profile should be controlled according to its clinical indications. In current study, responding to immediate increase in hypoxia inducible factor-1α (HIF-1α) level under hypoxia state followed by embolization of tumor feeding arteries, sodium bicarbonate (NaHCO3) was added to PLGA/17-AAG MS for fast drug release by CO2 gas generation in slightly acidic tumor microenvironment. With the aid of NaHCO3, initial burst release of 17-AAG was available without losing the micron-size and spherical shape of designed MS for embolization of artery. Acid-responsive CO2 gas generation and subsequent immediate release of 17-AAG from MS were successfully verified. PLGA/17-AAG/NaHCO3 MS-treated group exhibited higher antiproliferation and apoptosis induction efficacies in McA-RH7777 and SNU-761 cells. McA-RH7777 tumor-implanted rats treated by TACE using PLGA/17-AAG/NaHCO3 MS presented a complete therapeutic response. All these findings suggest that developed tumor microenvironment-responsive gas-generating MS can be efficiently applied to TACE therapy of HCC.

Hyaluronidase Inhibitor-Incorporated Cross-Linked Hyaluronic Acid Hydrogels for Subcutaneous Injection.

Hyaluronidase (HAase) inhibitor-incorporated hyaluronic acid (HA) hydrogel cross-linked with 1,4-butanediol diglycidyl ether (BDDE) was designed to reduce the toxicity risk induced by BDDE and its biodegradation rate in subcutaneous tissue. The formulation composition of hydrogel and its preparation method were optimized to have a high swelling ratio and drug content. Quercetin (QCT) and quetiapine (QTP), as an HAase inhibitor and model drug, respectively, were incorporated into the cross-linked hydrogel using the antisolvent precipitation method for extending their release after subcutaneous injection. The cross-linked HA (cHA)-based hydrogels displayed appropriate viscoelasticity and injectability for subcutaneous injection. The incorporation of QCT (as an HAase inhibitor) in the cHA hydrogel formulation resulted in slower in vitro and in vivo degradation profiles compared to the hydrogel without QCT. Single dosing of optimized hydrogel injected via a subcutaneous route in rats did not induce any acute toxicities in the blood chemistry and histological staining studies. In the pharmacokinetic study of rats following subcutaneous injection, the cHA hydrogel with QCT exhibited a lower maximum QTP concentration and longer half-life and mean residence time values compared to the hydrogel without QCT. All of these results support the designed HAase inhibitor-incorporated cHA hydrogel being a biocompatible subcutaneous injection formulation for sustained drug delivery.

Fenton-like reaction, glutathione reduction, and photothermal ablation-built-in hydrogels crosslinked by cupric sulfate for loco-regional cancer therapy.

Fenton-like reaction-associated chemodynamic therapy (CDT) and hyperthermia-inducing photothermal therapy (PTT)-combined crosslinked hydrogel systems were developed for loco-regional cancer therapy. Cupric sulfate (Cu) has been employed to crosslink the catechol-functionalized hyaluronic acid (HC) polymer-based gel via metal-catechol coordination and covalent bonding of the catechol group (by pH adjustment). Cu can also be used as a hydroxyl radical-generating agent with endogenous H2O2 in cancer cells mediated by Fenton-like reaction and it can reduce intracellular glutathione (GSH) levels leading to the inhibition of reactive oxygen species (ROS) scavenging. These two strategies can amplify the ROS-initiated CDT efficiency for combating cancer. The Cu-incorporated crosslinked hydrogel structure with pH modulation was appropriate for injectable gel formation via a single syringe. The incorporation of indocyanine green (ICG) into the hydrogel network and near-infrared (NIR) laser irradiation provided a temperature elevation sufficient for induction of hyperthermia in cancer therapy. It is expected that the designed HC/Cu/ICG hydrogel can be used safely and efficiently for local CDT and PTT of breast cancer.

Fast dissolving nanofiber mat for the local antimicrobial application of roxithromycin in oral cavity.

Fast disintegrating and dissolving nanofiber (NF) mat was devised to deliver roxithromycin for the treatment of the respiratory tract infection. NF membrane was made by an electrospinning process with poly(vinyl alcohol) (PVA), hydroxypropyl-ß-cyclodextrin (HP-ß-CD), and d-α-tocopheryl polyethylene glycol succinate (TPGS) for local application of roxithromycin. Roxithromycin has a poor water solubility thus HP-ß-CD is introduced for enhancing drug solubility by forming an inclusion complex in this study. The addition of TPGS provided multiple roles such as accelerating wetting, disintegration, and dissolution speed and overcoming bacterial resistance. Roxithromycin was successfully entrapped in NF structure and drug amorphization occurred during the electrospinning process. PVA/HP-ß-CD/TPGS/roxithromycin (PHTR) NF exhibited faster wetting, disintegration, and dissolution speed rather than the other NF mats. PHTR NF displayed higher antibacterial potentials in Gram-negative bacteria (E. coli) and Gram-positive bacteria (S. aureus) compared to other NF mat formulations. The administration of PHTR NF to oral cavity in pneumococcal disease mouse model provided the most efficient therapeutic potentials in lung tissue. Designed multiple phase-based NF mat may be one of powerful local drug delivery systems for the therapy of respiratory tract infection.

Serially pH-Modulated Hydrogels Based on Boronate Ester and Polydopamine Linkages for Local Cancer Therapy.

Elaborately and serially pH-modulated hydrogels possessing optimized viscoelastic natures for short gelation time and single syringe injection were designed for peritumoral injection of an anticancer agent. Boronate ester bonds between phenylboronic acid (PBA) (installed in HA-PBA (HP)) and dopamine (included in HA-dopamine (HD)) along with self-polymerization of dopamine (via interactions between HD conjugates) were introduced as the main cross-linking strategies of a hyaluronic acid (HA) hydrogel. Considering pKa values (8.0-9.5) of PBA and dopamine, the pH of each polymer dispersion was controlled elaborately for injection through a single syringe, and the final pH was tuned nearby the physiological pH (pH 7.8). The shear-thinning behavior, self-healing property, and single syringe injectability of a designed hydrogel cross-linked nearby physiological pH may provide its convenient application to peritumoral injection and prolonged retention in local cancer therapy. Erlotinib (ERT) was encapsulated in a microsphere (MS), and it was further embedded in an HP/HD-based hydrogel for sustained and locoregional delivery. A rheologically tuned hydrogel containing an ERT MS exhibited superior tumor-suppressive efficiencies compared to the other groups in A549 tumor-bearing mice. A designed injectable hydrogel through a single syringe system may be efficiently applied to local cancer therapy with lower toxicities to healthy organs.

Factors Affecting the End-of Life Care Competency of Tertiary Hospital Nurses.

Purpose: The purpose of this study was to investigate the levels of end-of-life care competency; knowledge, attitudes, and experiences regarding advance directives; perceptions of good death; and end-of-life care obstacles and supportive behaviors among tertiary care nurses. Methods: The participants were 150 nurses at a tertiary hospital in Jinju, Korea. The data collected using a questionnaire were analyzed using descriptive statistics, the t-test, analysis of variance, Pearson correlation coefficients, and stepwise multiple regression in SPSS for Windows version 24.0. Results: The mean (±SD) score of end-of-life care competency was 3.63 (±0.53) on a 5-point scale. A significant difference in end-of-life care competency was found according to whether nurses had experienced the death of a family member or acquaintance (P=0.029). According to stepwise multiple regression analysis, the factors affecting end-of-life care competency were the frequency of end-of-life care supportive behaviors (ß=0.38, P<0.001), experience with advance directives (ß=0.29, P<0.001), and marriage (ß=0.15, P=0.039). This model had an explanatory power of 27.9% (F=18.87, P<0.001). Conclusion: In order to improve nurses' end-of-life care competency, it is important to strengthen end-of-life care supportive behaviors by exposing nurses to those behaviors and providing frequent experience with advance directives.

Possible contribution of sialic acid to the enhanced tumor targeting efficiency of nanoparticles engineered with doxorubicin.

Doxorubicin (DOX)-engineered poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) including phloretin (PHL) were designed and the feasible contribution of sialic acid (SA) to the improved tumor targeting and penetration capabilities was elucidated in lung adenocarcinoma models. DOX has been clinically used as liposomal formulations after its introduction to the inner side of vehicles, however DOX is anchored in the outer surface of PLGA NPs for improved tumor penetration by interactions with SA in this study. DOX (positively charged at physiological pH) was adsorbed onto the negatively charged PLGA NPs via electrostatic interactions and consequent binding of SA (negatively charged at physiological pH) to DOX located in NPs was also elucidated. DOX layer in DOX@PLGA NPs rendered improved endocytosis and partial contribution of SA (expressed in cancer cells) to that endocytosis was demonstrated. DOX@PLGA/PHL NPs provided enhanced antiproliferation potentials in A549 cells rather than single agent (DOX or PHL)-installed NPs. In addition, DOX-SA interactions seemed to play critical roles in tumor infiltration and accumulation of DOX@PLGA NPs in A549 tumor-xenografted mouse model. All these findings support the novel use of DOX which is used for the surface engineering of NPs for improved tumor targeting and penetration.

Monopotassium phosphate-reinforced in situ forming injectable hyaluronic acid hydrogels for subcutaneous injection.

Monopotassium phosphate and pH modulation-reinforced hydrogel based on hyaluronic acid (HA) grafted with dopamine (dopa) was fabricated as one of subcutaneous injection formulations of donepezil (DPZ). Both incorporation of KH2PO4 and pH adjustment finally attributed to tuning viscoelastic and biodegradable properties of hydrogel system. Appropriate gelation time for in situ gel formation, single syringe injectability, self-healing capability, and viscoelastic features were accomplished with the optimization of KH2PO4 concentration in hydrogel systems. DPZ base (as a poorly water soluble drug) was encapsulated in poly(lactic-co-glycolic acid) (PLGA) microsphere (MS) and it was further embedded in the hydrogel structure for sustained drug release. Biodegradability of designed KH2PO4-incorporated HA-dopa/DPZ MS hydrogel system was assessed by optical imaging and the remained gel weight of crosslinked HA-dopa hydrogel group was 3.4-fold higher than that of unmodified HA-dopa mixture group on day 14 (p < 0.05). Subcutaneous injection of KH2PO4-incorporated HA-dopa/DPZ MS hydrogel did not induce any severe systemic toxicities. All these data suggest that designed HA-dopa/DPZ MS hydrogel structure crosslinked by KH2PO4 incorporation and pH adjustment can be one of promising subcutaneous injection formulations for sustained drug delivery.

Selenium and dopamine-crosslinked hyaluronic acid hydrogel for chemophotothermal cancer therapy.

Sodium selenite (Se)-directed crosslinked hydrogels based on hyaluronic acid (HA)-dopamine (HD), including indocyanine green (ICG), were developed for local therapy of breast cancer. Se can induce polymerization of dopamine (in HD conjugate) by making alkaline pH value, coordinate with the functional groups of HD, and kill cancer cells by pro-oxidant effects. ICG can be entrapped in the crosslinked HD/Se hydrogel network and long lasting photothermal efficacies can be maintained for cancer therapy. HD conjugate was synthesized via an amide linkage between carboxylic acid group of HA and amine group of dopamine. HD/Se gel was fabricated by covalent bonding of dopamine group (in HD conjugate) and the coordination between selenium and functional groups of HD. Controlled rheological properties of HD/Se/ICG gel may provide easy injectability and slow biodegradability. Sufficient photothermal efficiencies were acquired after near-infrared (NIR) laser irradiation. HD/Se/ICG gel structure was remained in the mouse for 2 weeks and severe systemic toxicities were not observed in blood and histological assays. Intratumoral injection of HD/Se/ICG gel with NIR laser irradiation provided the most efficient tumor growth inhibition capability without severe systemic toxicities. HD/Se/ICG hydrogel structure can be introduced as a promising multifunctional platform for local therapy of breast cancers.

Effect of Different Processing Methods on the Accumulation of the Phenolic Compounds and Antioxidant Profile of Broomcorn Millet (Panicum miliaceum L.) Flour.

Broomcorn millet (Panicum miliaceum L.) is an important nutritious ancient minor-cereal food crop. However, this crop is little explored in the food processing arena to improve its functionality. In this context, different processing methods were applied to enhance the secondary compounds of broomcorn millet. Four different individual methods such as roasting, steaming, puffing, and extrusion were applied at 110 °C to enhance the functional attributes of millet flour. It was observed that the significantly highest content of total phenolic (TP) (670 mg/100 g of ferulic acid equivalent) and total flavonoid (TF) (391 mg/100 g of rutin equivalent ) was attained in the roasted whole millet followed by steaming (315 mg/100 g, 282 mg/100 g), puffing (645 mg/100 g, 304 mg/100 g), extrusion (455 mg/100 g, 219 mg/100 g), and control (295 mg/100 g, 183 mg/100 g). The chromatographic analysis showed a greater content of single phenolic acids such as syringic acid, gallic acid, 4-hydroxy benzoic acid, ferulic acid, sinapic acid, and catechin in roasted millet compared to control, and the content of each acid was higher in whole millet than dehulled. Results also indicated that the content of ferulic acid was relatively higher among the quantified single phenolic acid from broomcorn millet. Likewise, in comparison with dehulled millet, the roasted whole millet showed higher total antioxidant capacity, measured by the 2,2-diphenyl-1 picryl hydrazyl (DPPH), the ferric reducing antioxidant power assay (FRAP), the phosphomolybdenum method (PPMD), and the hydroxyl radical scavenging capacity (HRSC) method. Lastly, it is concluded that the roasting method should be taken into consideration in the processing of broomcorn millet to enhance the content of nutraceutical compounds and improve its functionality.

Placental and lactational transfer of decabromodiphenyl ether and 2,2',4,4'-tetrabromodiphenyl ether in dam-offspring pairs of Sprague-Dawley rats.

Although several studies have conducted maternal transfer of individual PBDE congener in experimental animals, there is a paucity of research on differences in maternal transfer of PBDE congeners. The purpose of the study was to investigate and compare placental and lactational transfer of BDE 47, -209 and its metabolites in rat dam-offspring pairs following repeated administration of BDE 47 and -209. 13C-BDE 47, BDE 209 and its debrominated congeners were detected both in dam serum and offspring body, which indicates that PBDEs can be maternally transferred. In addition, BDE 196 and -197 appeared in offspring body earlier than in maternal serum, which suggests that debromination can be occur in offspring body. BDE 209 increased in both dam and offspring while levels of 13C-BDE 47 was not increased in dam serum. 13C-BDE 47 seems to be stored in breast milk rather than in maternal serum, which can be assumed through the drastic increase of the congener in suckling pups. The magnitude of lactational transfer of the administered congeners was greater than that of placental transfer. And 13C-BDE 47 was relatively more transferred to suckling pups than BDE 209 through breastfeeding.