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1.
Chem Commun (Camb) ; 55(60): 8772-8775, 2019 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-31172998

RESUMO

We introduced a new concept to the control of wetting characteristics by modulating the degree of atomic defects of two-dimensional transition metal dichalcogenide nanoassemblies of molybdenum disulfide. This work shed new light on the role of atomic vacancies on wetting characteristic that can be leveraged to develop a new class of superhydrophobic surfaces for various applications without altering their topography.


Assuntos
Adesão Celular , Dissulfetos/química , Células-Tronco Mesenquimais/fisiologia , Molibdênio/química , Nanoestruturas/química , Humanos , Interações Hidrofóbicas e Hidrofílicas , Molhabilidade
2.
Proc Natl Acad Sci U S A ; 115(17): E3905-E3913, 2018 04 24.
Artigo em Inglês | MEDLINE | ID: mdl-29643075

RESUMO

Two-dimensional nanomaterials, an ultrathin class of materials such as graphene, nanoclays, transition metal dichalcogenides (TMDs), and transition metal oxides (TMOs), have emerged as a new generation of materials due to their unique properties relative to macroscale counterparts. However, little is known about the transcriptome dynamics following exposure to these nanomaterials. Here, we investigate the interactions of 2D nanosilicates, a layered clay, with human mesenchymal stem cells (hMSCs) at the whole-transcriptome level by high-throughput sequencing (RNA-seq). Analysis of cell-nanosilicate interactions by monitoring changes in transcriptome profile uncovered key biophysical and biochemical cellular pathways triggered by nanosilicates. A widespread alteration of genes was observed due to nanosilicate exposure as more than 4,000 genes were differentially expressed. The change in mRNA expression levels revealed clathrin-mediated endocytosis of nanosilicates. Nanosilicate attachment to the cell membrane and subsequent cellular internalization activated stress-responsive pathways such as mitogen-activated protein kinase (MAPK), which subsequently directed hMSC differentiation toward osteogenic and chondrogenic lineages. This study provides transcriptomic insight on the role of surface-mediated cellular signaling triggered by nanomaterials and enables development of nanomaterials-based therapeutics for regenerative medicine. This approach in understanding nanomaterial-cell interactions illustrates how change in transcriptomic profile can predict downstream effects following nanomaterial treatment.


Assuntos
Perfilação da Expressão Gênica , Regulação da Expressão Gênica/efeitos dos fármacos , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Células-Tronco Mesenquimais/metabolismo , Nanopartículas , Silicatos/farmacologia , Transcriptoma/efeitos dos fármacos , Clatrina/metabolismo , Endocitose/efeitos dos fármacos , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Células-Tronco Mesenquimais/citologia
3.
J Biomed Mater Res A ; 106(7): 2048-2058, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29577576

RESUMO

Nanoparticle shape has emerged as a key regulator of nanoparticle transport across physiological barriers, intracellular uptake, and biodistribution. We report a facile approach to synthesize ellipsoidal nanoparticles through self-assembly of poly(glycerol sebacate)-co-poly(ethylene glycol) (PGS-co-PEG). The PGS-PEG nanoparticle system is highly tunable, and the semiaxis length of the nanoparticles can be modulated by changing PGS-PEG molar ratio and incorporating therapeutics. As both PGS and PEG are highly biocompatible, the PGS-co-PEG nanoparticles show high hemo-, immuno-, and cytocompatibility. Our data suggest that PGS-co-PEG nanoparticles have the potential for use in a wide range of biomedical applications including regenerative medicine, stem cell engineering, immune modulation, and cancer therapeutics. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 2048-2058, 2018.

4.
Dalton Trans ; 47(2): 287-291, 2018 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-29188833

RESUMO

Quick and easy recovery without the loss of the photocatalytic activity of the catalysing agent is an effective way to meet the challenges associated with the high cost of hazard-free hydrogen production. A '2D/0D' covalently conjugated nanocomposite of MoS2/Fe3O4 has shown efficient catalyzing ability for five cycles of dye-sensitized H2 evolution.

5.
Nanoscale ; 9(40): 15379-15389, 2017 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-28975171

RESUMO

"Smart" hydrogels are an emerging class of biomaterials that respond to external stimuli and have been investigated for a range of biomedical applications, including therapeutic delivery and regenerative engineering. Stimuli-responsive nanogels constructed of thermoresponsive polymers such as poly(N-isopropylacrylamide-co-acrylamide) (poly(NIPAM-co-AM)) and magnetic nanoparticles (MNPs) have been developed as "smart carriers" for on-demand delivery of therapeutic biomolecules via magneto-thermal activation. However, due to their small size and systemic introduction, these poly(NIPAM-co-AM)/MNP nanogels result in limited control over long-term, localized therapeutic delivery. Here, we developed an injectable nanoengineered hydrogel loaded with poly(NIPAM-co-AM)/MNPs for localized, on-demand delivery of therapeutics (doxorubicin (DOX)). We have engineered shear-thinning and self-recoverable hydrogels by modulating the crosslinking density of a gelatin methacrylate (GelMA) network. Poly(NIPAM-co-AM)/MNP nanogels loaded with DOX were entrapped within a GelMA pre-polymer solution prior to crosslinking. The temperature and magnetic field dependent release of loaded DOX was observed from the nanoengineered hydrogels (GelMA/(poly(NIPAM-co-AM)/MNPs)). Finally, the in vitro efficacy of DOX released from injectable nanoengineered hydrogels was investigated using preosteoblast and osteosarcoma cells. Overall, these results demonstrated that the injectable nanoengineered hydrogels could be used for on-demand and localized therapeutic delivery for biomedical applications.

6.
Adv Mater ; 29(36)2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28940819

RESUMO

A new approach of vacancy-driven gelation to obtain chemically crosslinked hydrogels from defect-rich 2D molybdenum disulfide (MoS2 ) nanoassemblies and polymeric binder is reported. This approach utilizes the planar and edge atomic defects available on the surface of the 2D MoS2 nanoassemblies to form mechanically resilient and elastomeric nanocomposite hydrogels. The atomic defects present on the lattice plane of 2D MoS2 nanoassemblies are due to atomic vacancies and can act as an active center for vacancy-driven gelation with a thiol-activated terminal such as four-arm poly(ethylene glycol)-thiol (PEG-SH) via chemisorption. By modulating the number of vacancies on the 2D MoS2 nanoassemblies, the physical and chemical properties of the hydrogel network can be controlled. This vacancy-driven gelation process does not require external stimuli such as UV exposure, chemical initiator, or thermal agitation for crosslinking and thus provides a nontoxic and facile approach to encapsulate cells and proteins. 2D MoS2 nanoassemblies are cytocompatible, and encapsulated cells in the nanocomposite hydrogels show high viability. Overall, the nanoengineered hydrogel obtained from vacancy-driven gelation is mechanically resilient and can be used for a range of biomedical applications including tissue engineering, regenerative medicine, and cell and therapeutic delivery.

7.
ACS Nano ; 11(8): 7690-7696, 2017 08 22.
Artigo em Inglês | MEDLINE | ID: mdl-28745508

RESUMO

Our current understanding of the mechanical properties of nanostructured biomaterials is rather limited to invasive/destructive and low-throughput techniques such as atomic force microscopy, optical tweezers, and shear rheology. In this report, we demonstrate the capabilities of recently developed dual Brillouin/Raman spectroscopy to interrogate the mechanical and chemical properties of nanostructured hydrogel networks. The results obtained from Brillouin spectroscopy show an excellent correlation with the conventional uniaxial and shear mechanical testing. Moreover, it is confirmed that, unlike the macroscopic conventional mechanical measurement techniques, Brillouin spectroscopy can provide the elasticity characteristic of biomaterials at a mesoscale length, which is remarkably important for understanding complex cell-biomaterial interactions. The proposed technique experimentally demonstrated the capability of studying biomaterials in their natural environment and may facilitate future fabrication and inspection of biomaterials for various biomedical and biotechnological applications.

8.
Integr Biol (Camb) ; 9(6): 555-565, 2017 06 19.
Artigo em Inglês | MEDLINE | ID: mdl-28513646

RESUMO

Magnetic liposome-mediated combined chemotherapy and hyperthermia is gaining importance as an effective therapeutic modality for cancer. However, control and maintenance of optimum hyperthermia are major challenges in clinical settings due to the overheating of tissues. To overcome this problem, we developed a novel magnetic liposomes formulation co-entrapping a dextran coated biphasic suspension of La0.75Sr0.25MnO3 (LSMO) and iron oxide (Fe3O4) nanoparticles for self-controlled hyperthermia and chemotherapy. However, the general apprehension about biocompatibility and safety of the newly developed formulation needs to be addressed. In this work, in vitro and in vivo biocompatibility and therapeutic evaluation studies of the novel magnetic liposomes are reported. Biocompatibility study of the magnetic liposomes formulation was carried out to evaluate the signs of preliminary systemic toxicity, if any, following intravenous administration of the magnetic liposomes in Swiss mice. Therapeutic efficacy of the magnetic liposomes formulation was evaluated in the fibrosarcoma tumour bearing mouse model. Fibrosarcoma tumour-bearing mice were subjected to hyperthermia following intratumoral injection of single or double doses of the magnetic liposomes with or without chemotherapeutic drug paclitaxel. Hyperthermia (three spurts, each at 3 days interval) with drug loaded magnetic liposomes following single dose administration reduced the growth of tumours by 2.5 fold (mean tumour volume 2356 ± 550 mm3) whereas the double dose treatment reduced the tumour growth by 3.6 fold (mean tumour volume 1045 ± 440 mm3) compared to their corresponding control (mean tumour volume 3782 ± 515 mm3). At the end of the tumour efficacy studies, the presence of MNPs was studied in the remnant tumour tissues and vital organs of the mice. No significant leaching or drainage of the magnetic liposomes during the study was observed from the tumour site to the other vital organs of the body, suggesting again the potential of the novel magnetic liposomes formulation for possibility of developing as an effective modality for treatment of drug resistant or physiologically vulnerable cancer.


Assuntos
Hipertermia Induzida/métodos , Lipossomos/uso terapêutico , Magnetismo , Neoplasias/terapia , Animais , Antineoplásicos Fitogênicos/administração & dosagem , Materiais Biocompatíveis/uso terapêutico , Linhagem Celular Tumoral , Terapia Combinada , Feminino , Humanos , Lipossomos/administração & dosagem , Lipossomos/toxicidade , Nanopartículas de Magnetita/administração & dosagem , Nanopartículas de Magnetita/uso terapêutico , Nanopartículas de Magnetita/toxicidade , Teste de Materiais , Camundongos , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Paclitaxel/administração & dosagem , Sarcoma Experimental/tratamento farmacológico , Sarcoma Experimental/metabolismo , Sarcoma Experimental/terapia , Distribuição Tecidual
9.
Nanoscale ; 8(24): 12362-72, 2016 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-27270567

RESUMO

Injectable hydrogels are investigated for cell encapsulation and delivery as they can shield cells from high shear forces. One of the approaches to obtain injectable hydrogels is to reinforce polymeric networks with high aspect ratio nanoparticles such as two-dimensional (2D) nanomaterials. 2D nanomaterials are an emerging class of ultrathin materials with a high degree of anisotropy and they strongly interact with polymers resulting in the formation of shear-thinning hydrogels. Here, we present 2D nanosilicate reinforced kappa-carrageenan (κCA) hydrogels for cellular delivery. κCA is a natural polysaccharide that resembles native glycosaminoglycans and can form brittle hydrogels via ionic crosslinking. The chemical modification of κCA with photocrosslinkable methacrylate groups renders the formation of a covalently crosslinked network (MκCA). Reinforcing the MκCA with 2D nanosilicates results in shear-thinning characteristics, and enhanced mechanical stiffness, elastomeric properties, and physiological stability. The shear-thinning characteristics of nanocomposite hydrogels are investigated for human mesenchymal stem cell (hMSC) delivery. The hMSCs showed high cell viability after injection and encapsulated cells showed a circular morphology. The proposed shear-thinning nanoengineered hydrogels can be used for cell delivery for cartilage tissue regeneration and 3D bioprinting.


Assuntos
Carragenina/química , Hidrogéis/química , Células-Tronco Mesenquimais/citologia , Nanocompostos/química , Cartilagem , Células Cultivadas , Humanos
10.
J Biomed Mater Res A ; 104(4): 879-88, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26650507

RESUMO

Nanocomposite biomaterials are extensively investigated for cell and tissue engineering applications due their unique physical, chemical and biological characteristics. Here, we investigated the mechanical, rheological, and degradation properties of photocrosslinkable and elastomeric nanocomposite hydrogels from nanohydroxyapatite (nHAp) and gelatin methacryloyl (GelMA). The addition of nHAp resulted in a significant increase in mechanical stiffness and physiological stability. Cells readily adhere and proliferate on the nanocomposite surfaces. Cyclic stretching of cells on the elastomeric nanocomposites revealed that nHAp elicited a stronger alignment response in the direction of strain. In vitro studies highlight enhanced bioactivity of nanocomposites as determined by alkaline phosphate (ALP) activity. Overall, the elastomeric and photocrosslinkable nanocomposite hydrogels can be used for minimally invasive therapy for bone regeneration.


Assuntos
Regeneração Óssea , Substitutos Ósseos/química , Durapatita/química , Gelatina/química , Hidrogéis/química , Nanocompostos/química , Osteoblastos/citologia , Animais , Adesão Celular , Diferenciação Celular , Linhagem Celular , Movimento Celular , Proliferação de Células , Luz , Camundongos , Nanocompostos/ultraestrutura , Polímeros/química
11.
ACS Nano ; 10(1): 246-56, 2016 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-26670176

RESUMO

Although hydrogels are able to mimic native tissue microenvironments, their utility for biomedical applications is severely hampered due to limited mechanical stiffness and low toughness. Despite recent progress in designing stiff and tough hydrogels, it is still challenging to achieve a cell-friendly, high modulus construct. Here, we report a highly efficient method to reinforce collagen-based hydrogels using extremely low concentrations of a nanoparticulate-reinforcing agent that acts as a cross-link epicenter. Extraordinarily, the addition of these nanoparticles at a 10 000-fold lower concentration relative to polymer resulted in a more than 10-fold increase in mechanical stiffness and a 20-fold increase in toughness. We attribute the high stiffness of the nanocomposite network to the chemical functionality of the nanoparticles, which enabled the cross-linking of multiple polymeric chains to the nanoparticle surface. The mechanical stiffness of the nanoengineered hydrogel can be tailored between 0.2 and 200 kPa simply by manipulating the size of the nanoparticles (4, 8, and 12 nm), as well as the concentrations of the nanoparticles and polymer. Moreover, cells can be easily encapsulated within the nanoparticulate-reinforced hydrogel network, showing high viability. In addition, encapsulated cells were able to sense and respond to matrix stiffness. Overall, these results demonstrate a facile approach to modulate the mechanical stiffness of collagen-based hydrogels and may have broad utility for various biomedical applications, including use as tissue-engineered scaffolds and cell/protein delivery vehicles.


Assuntos
Dureza , Hidrogéis/química , Nanocompostos/química , Nanopartículas/química , Animais , Células Imobilizadas/citologia , Células Imobilizadas/fisiologia , Colágeno/química , Dopamina/química , Óxido Ferroso-Férrico/química , Gelatina/química , Testes de Dureza , Humanos , Teste de Materiais , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/fisiologia , Metacrilatos/química , Camundongos , Células NIH 3T3 , Nanocompostos/ultraestrutura , Nanopartículas/ultraestrutura , Tamanho da Partícula , Polietilenoglicóis/química
12.
Colloids Surf B Biointerfaces ; 136: 625-33, 2015 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-26477008

RESUMO

Bladder cancer is one of the deadliest forms of cancer in modern medicine which despite recent progress has remained incurable and challenging for researchers. There is unmet need to address this endemic as the number of patients are growing by about 10,000 every year world-wide. Here, we report a minimally invasive magnetic chemotherapy method to address this problem where polyethylene glycol (PEG) functionalized Fe3O4 magnetic nanostructures (MNS) are homogeneously embedded in thermally responsive poly(N-isopropylacrylamide, NIPAAm) hydrogels (HG). The system (HG-MNS) loaded with anti-cancer drug doxorubicin (DOX) incubated with cancer cell lines subjected to external radiofrequency (RF) field can remotely stimulate the release of drug smartly at the site. The in vitro efficacy investigated on bladder cancer (T-24) cell lines showed the potential of the system in dealing with the disease successfully. Further, the materials preferential accumulation via systemic delivery was studied using swiss mice model. Vital tissue organs like liver, lung and heart were analysed by magnetic resonance imaging (MRI). A detail accounts of the materials optimization, cytotoxicity and anti-proliferation activity tests with apoptosis analysis by flow cytometry after RF exposure (250 kHz) to the cells and in vivo biodistribution data are discussed in the paper.


Assuntos
Hidrogéis/uso terapêutico , Neoplasias da Bexiga Urinária/terapia , Humanos , Hidrogéis/farmacocinética , Distribuição Tecidual
13.
Biomaterials ; 63: 24-34, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26072995

RESUMO

Ex vivo engineered three-dimensional organotypic cultures have enabled the real-time study and control of biological functioning of mammalian tissues. Organs of broad interest where its architectural, cellular, and molecular complexity has prevented progress in ex vivo engineering are the secondary immune organs. Ex vivo immune organs can enable mechanistic understanding of the immune system and more importantly, accelerate the translation of immunotherapies as well as a deeper understanding of the mechanisms that lead to their malignant transformation into a variety of B and T cell malignancies. However, till date, no modular ex vivo immune organ has been developed with an ability to control the rate of immune reaction through tunable design parameter. Here we describe a B cell follicle organoid made of nanocomposite biomaterials, which recapitulates the anatomical microenvironment of a lymphoid tissue that provides the basis to induce an accelerated germinal center (GC) reaction by continuously providing extracellular matrix (ECM) and cell-cell signals to naïve B cells. Compared to existing co-cultures, immune organoids provide a control over primary B cell proliferation with ∼100-fold higher and rapid differentiation to the GC phenotype with robust antibody class switching.


Assuntos
Linfócitos B/citologia , Materiais Biocompatíveis/química , Centro Germinativo/citologia , Nanocompostos/química , Organoides/citologia , Animais , Linfócitos B/imunologia , Movimento Celular , Proliferação de Células , Células Cultivadas , Centro Germinativo/imunologia , Camundongos Endogâmicos C57BL , Nanocompostos/ultraestrutura , Técnicas de Cultura de Órgãos/métodos , Organoides/imunologia , Engenharia Tecidual/métodos
14.
ACS Nano ; 9(3): 3109-18, 2015 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-25674809

RESUMO

Despite bone's impressive ability to heal after traumatic injuries and fractures, a significant need still exists for developing strategies to promote healing of nonunion defects. To address this issue, we developed collagen-based hydrogels containing two-dimensional nanosilicates. Nanosilicates are ultrathin nanomaterials with a high degree of anisotropy and functionality that results in enhanced surface interactions with biological entities compared to their respective three-dimensional counterparts. The addition of nanosilicates resulted in a 4-fold increase in compressive modulus along with an increase in pore size compared to collagen-based hydrogels. In vitro evaluation indicated that the nanocomposite hydrogels are capable of promoting osteogenesis in the absence of any osteoinductive factors. A 3-fold increase in alkaline phosphatase activity and a 4-fold increase in the formation of a mineralized matrix were observed with the addition of the nanosilicates to the collagen-based hydrogels. Overall, these results demonstrate the multiple functions of nanosilicates conducive to the regeneration of bone in nonunion defects, including increased network stiffness and porosity, injectability, and enhanced mineralized matrix formation in a growth-factor-free microenvironment.


Assuntos
Osso e Ossos/citologia , Osso e Ossos/efeitos dos fármacos , Hidrogéis/química , Hidrogéis/farmacologia , Nanocompostos/química , Nanotecnologia/métodos , Engenharia Tecidual/métodos , Animais , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Osso e Ossos/fisiologia , Calcificação Fisiológica/efeitos dos fármacos , Adesão Celular/efeitos dos fármacos , Linhagem Celular , Colágeno/química , Gelatina/química , Fenômenos Mecânicos , Camundongos , Osteogênese/efeitos dos fármacos , Silicatos/química
15.
J Nanosci Nanotechnol ; 14(6): 4082-9, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24738355

RESUMO

Dual stimuli pH and temperature-responsive nanohydrogels based on poly(N-isopropylacrylamide)-chitosan have been synthesized. Fe3O4 magnetic nanoparticles (NPs) (-12 nm) have been incorporated into hydrogels to achieve temperature optimized magnetic nanohydrogel (MNHG) for magnetic hyperthermia with lower critical solution temperature, LCST > 42 degrees C. The composite was further investigated for its potential application in drug delivery and in vitro cancer cell cytotoxicity. Water-bath assisted drug release studies were carried out using anti-cancer drug doxorubicin (DOX) in acetate buffer medium (pH - 4.6) to mimic tumor cell environment which is slightly acidic in nature. The pH and temperature responsiveness of the system was demonstrated by DOX release under different conditions. The released amount of DOX was found to be nearly 4 microg/mg above hyperthermia temperature (-42 degrees C) as opposed to only 1.9 microg/mg of MNHG at physiological temperature (37 degrees C) under acidic environment (pH - 4.6). Further, AC magnetic field (AMF) induced heating of NPs entrapped inside hydrogels showed appreciable reduction of cell population in human breast (MCF-7) and cervical carcinoma (HeLa) cell lines for given duration of field exposures. Quantitatively, death percentages of HeLa cells were nearly 35 and 45% while for MCF-7, these were 20 and 70% when exposed to AMF for 10 and 30 min, respectively. Further the cell killing efficacy of MNHG loaded with DOX was assessed under AMF using HeLa cell lines. The AMF induced heat triggered DOX release from the MNHG which enhances the cell death up to 85% due to combined effect of thermo-chemotherapeutics. The present system with both pH and temperature responsivity serves as a promising candidate for a combination therapy.


Assuntos
Doxorrubicina/administração & dosagem , Hidrogéis/química , Hipertermia Induzida/métodos , Terapia de Campo Magnético/métodos , Nanopartículas de Magnetita/uso terapêutico , Nanocápsulas/administração & dosagem , Neoplasias Experimentais/terapia , Antibióticos Antineoplásicos/administração & dosagem , Antibióticos Antineoplásicos/química , Apoptose/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Terapia Combinada , Preparações de Ação Retardada/administração & dosagem , Preparações de Ação Retardada/química , Células HeLa , Humanos , Concentração de Íons de Hidrogênio , Nanopartículas de Magnetita/química , Nanocápsulas/química , Nanocápsulas/ultraestrutura , Neoplasias Experimentais/patologia , Temperatura Ambiente , Resultado do Tratamento
16.
ACS Appl Mater Interfaces ; 6(9): 6237-47, 2014 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-24716547

RESUMO

We report the development of thermoresponsive magnetic hydrogels based on poly(N-isopropylacrylamide) encapsulation of Fe3O4 magnetic nanostructures (MNS). In particular, we examined the effects of hydrogels encapsulated with poly-ethylene glycol (PEG) and polyhedral oligomeric silsesquioxane (POSS) surface modified Fe3O4 MNS on magnetic resonance (MR) T2 (transverse spin relaxation) contrast enhancement and associated delivery efficacy of absorbed therapeutic cargo. The microstructural characterization reveal the regular spherical shape and size (∼200 nm) of the hydrogels with elevated hydrophilic to hydrophobic transition temperature (∼40 °C) characterized by LCST (lower critical solution temperature) due to the presence of encapsulated MNS. The hydrogel-MNS (HGMNS) system encapsulated with PEG functionalized Fe3O4 of 12 nm size (HGMNS-PEG-12) exhibited relaxivity rate (r2) of 173 mM(-1) s(-1) compared to 129 mM(-1) s(-1) obtained for hydrogel-MNS system encapsulated with POSS functionalized Fe3O4 (HGMNS-POSS-12) of the same size. Further studies with HGMNS-PEG-12 with absorbed drug doxorubicin (DOX) reveals approximately two-fold enhance in release during 1 h RF (radio-frequency) field exposure followed by 24 h incubation at 37 °C. Quantitatively, it is 2.1 µg mg(-1) (DOX/HGMNS) DOX release with RF exposure while only 0.9 µg mg(-1) release without RF exposure for the same period of incubation. Such enhanced release of therapeutic cargo is attributed to micro-environmental heating in the surroundings of MNS as well as magneto-mechanical vibrations under high frequency RF inside hydrogels. Similarly, RF-induced in vitro localized drug delivery studies with HeLa cell lines for HGMNS-PEG-12 resulted in more than 80% cell death with RF field exposures for 1 h. We therefore believe that magnetic hydrogel system has in vivo theranostic potential given high MR contrast enhancement from encapsulated MNS and RF-induced localized therapeutic delivery in one nanoconstruct.


Assuntos
Hidrogéis , Magnetismo , Células HeLa , Humanos , Espectroscopia de Ressonância Magnética , Microscopia de Força Atômica , Microscopia Eletrônica de Varredura , Temperatura Ambiente
17.
Colloids Surf B Biointerfaces ; 81(1): 185-94, 2010 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-20702074

RESUMO

Poly(NIPAAm)-CS based nanohydrogels (NHGs) and iron oxide (Fe(3)O(4)) magnetic nanoparticles encapsulated magnetic nanohydrogels (MNHGs) were synthesized by free radical polymerization of N-isopropylacrylamide (NIPAAm) at 60 degrees C in presence of chitosan (CS) in different feed ratios. The polymerization of NIPAAm and the presence of CS as well as Fe(3)O(4) in hydrogels were confirmed from Fourier transform infrared (FTIR) spectra and X-ray diffraction (XRD), respectively. (13)C solid state nuclear magnetic resonance (NMR) spectra clearly revealed the grafting of CS into poly(NIPAAm). The scanning electron microscopy (SEM) and atomic force microscopy (AFM) images showed the formation of spherical shaped NHGs of different sizes ranging from 50 nm to 200 nm depending upon the feed ratios of CS and NIPAAm, which was further supported by mean hydrodynamic diameter measured by dynamic light scattering (DLS). It has been observed that CS not only served as a cross linker during polymerization but also plays a critical role in controlling the growth of NHG and enhancement in lower critical solution temperature (LCST). The encapsulation of Fe(3)O(4) nanoparticles (10-12 nm) into NHGs ( approximately 200 nm) was confirmed by transmission electron microscopy (TEM) and further corroborated with magnetic force microscopy (MFM) image. The LCST of poly(NIPAAm) was found to increase with increasing weight ratio of CS to NIPAAm. Furthermore, the encapsulation of iron oxide nanoparticles into hydrogels also caused an increment in LCST. Specifically, temperature optimized NHG and MNHG were fabricated having LCST close to 42 degrees C (hyperthermia temperature). The MNHG shows optimal magnetization, good specific absorption rate (under external AC magnetic field) and excellent cytocompatibility with L929 cell lines, which may find potential applications in hyperthermia treatment of cancer and targeted drug delivery.


Assuntos
Acrilamidas/química , Quitosana/química , Hidrogéis/química , Nanopartículas/química , Polímeros/química , Resinas Acrílicas , Animais , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Óxido Ferroso-Férrico/química , Hidrogéis/toxicidade , Magnetismo , Microscopia de Força Atômica , Microscopia Eletrônica , Nanopartículas/toxicidade , Nanopartículas/ultraestrutura , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura Ambiente , Difração de Raios X
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