4,035 research outputs found
Chemical Design of Biocompatible Iron Oxide Nanoparticles for Medical Applications
No full textIron oxide nanoparticles are one of the most versatile and safe nanomaterials used in medicine. Recent progress in nanochemistry enables fine control of the size, crystallinity, uniformity, and surface properties of iron oxide nanoparticles. In this review, the synthesis of chemically designed biocompatible iron oxide nanoparticles with improved quality and reduced toxicity is discussed for use in diverse biomedical applications.11801881sciescopu
Chemical synthesis and assembly of uniformly sized iron oxide nanoparticles for medical applications
No full textConspectusMagnetic iron oxide nanoparticles have been extensively investigated for their various biomedical applications including diagnostic imaging, biological sensing, drug, cell, and gene delivery, and cell tracking. Recent advances in the designed synthesis and assembly of uniformly sized iron oxide nanoparticles have brought innovation in the field of nanomedicine. This Account provides a review on the recent progresses in the controlled synthesis and assembly of uniformly sized iron oxide nanoparticles for medical applications. In particular, it focuses on three topics: stringent control of particle size during synthesis via the heat-up process, surface modification for the high stability and biocompatibility of the nanoparticles for diagnostic purposes, and assembly of the nanoparticles within polymers or mesoporous silica matrices for theranostic applications.Using extremely small 3 nm sized iron oxide nanoparticles (ESION), a new nontoxic T1 MRI contrast agent was realized for high-resolution MRI of blood vessels down to 0.2 mm. Ferrimagnetic iron oxide nanoparticles (FION) that are larger than 20 nm exhibit extremely large magnetization and coercivity values. The cells labeled with FIONs showed very high T2 contrast effect so that even a single cell can be readily imaged.Designed assembly of iron oxide nanoparticles with mesoporous silica and polymers was conducted to fabricate multifunctional nanoparticles for theranostic applications. Mesoporous silica nanoparticles are excellent scaffolds for iron oxide nanoparticles, providing magnetic resonance and fluorescence imaging modalities as well as the functionality of the drug delivery vehicle. Polymeric ligands could be designed to respond to various biological stimuli such as pH, temperature, and enzymatic activity. For example, we fabricated tumor pH-sensitive magnetic nanogrenades (termed PMNs) composed of self-assembled iron oxide nanoparticles and pH-responsive ligands. They were utilized to visualize small tumors (<3 mm) via pH-responsive T1 MRI and fluorescence imaging. Also, superior photodynamic therapeutic efficacy in highly drug-resistant heterogeneous tumors was observed. We expect that these multifunctional and bioresponsive nanoplatforms based on uniformly sized iron oxide nanoparticles will provide more unique theranostic approaches in clinical uses. © 2015 American Chemical Society11511631sciescopu
The surface science of nanocrystals
No full textAll nanomaterials share a common feature of large surface-to-volume ratio, making their surfaces the dominant player in many physical and chemical processes. Surface ligands-molecules that bind to the surface-are an essential component of nanomaterial synthesis, processing and application. Understanding the structure and properties of nanoscale interfaces requires an intricate mix of concepts and techniques borrowed from surface science and coordination chemistry. Our Review elaborates these connections and discusses the bonding, electronic structure and chemical transformations at nanomaterial surfaces. We specifically focus on the role of surface ligands in tuning and rationally designing properties of functional nanomaterials. Given their importance for biomedical (imaging, diagnostics and therapeutics) and optoelectronic (light-emitting devices, transistors, solar cells) applications, we end with an assessment of application-targeted surface engineering. © 2016 Macmillan Publishers Limited. All rights reserved32233
Surface ligands in synthesis, modification, assembly and biomedical applications of nanoparticles
No full textNanotechnology hasreceivedextraordinaryattentionrecentlyduetoitsburgeon-
ing roleinbiomedicalscience.Thematerialscomposingthenanoparticlesproducefascinating
and diversefunctionalitiesasaresultoftheirexceptionallysmallsize.Infact,evenseemingly
insignificant changesinparticlesizecanhaveprofoundeffectsontheseproperties.Thussize
control, bothduringsynthesisandinparticlesuspensions,isa sine quanon for functionality.
This canbeaccomplishedbymaskingtheparticlesurfacewithamultitudeofdifferentlig-
ands. Notonlycansurfaceligandsconstrainthegrowthofnucleation,theycanalsodirectthe
shape ofcrystallization.Howevernosingleligandcandoeverything.Fortunatelyligandsare
essentially fungibleandcanbeexchangedatvarioustimestoconferthedesiredproperties
to theparticle.Thiscanincludeprotectingtheparticlefromharshaqueousconditions,such
as pHextremes,maximizingopticalpropertiesfordiagnosticsorshieldingtheparticlefrom
potentially hostileconditionsfoundinthebody.Becausethesemoietiesinteractubiquitously
with variousbiologicalmaterials,particularlyproteins,thereneedstobearationalizeddesign
of surfaceligands.Thedesignoftheligandcanhavecrucialeffectsonbiodistributionaswell
as evasionofbiologicaldefenses.Ligandscanevenbedesignedtoprovidenewfunctionality
in responsetovariousenvironmentalstimulitoimprovetheirtherapeuticordiagnosticcapa-
bilities. Consideringtheimportanceofligandsthenonthisemergingfield,thisreviewwill
thoroughly considertheliganddesignforthevariousstepsofnanodevelopment,fromsynthesis
and assemblythroughbiomedicaltranslation.
© 2014ElsevierLtd.Allrightsreserved.171761sciescopu
Iron Oxide Based Nanoparticles for Multimodal Imaging and Magnetoresponsive Therapy
No full text[No abstract available]12372471sciescopu
Cancer imaging: Lighting up tumours
No full textGao and colleagues have developed a polymeric, micelle-based nanoprobe that is highly responsive to both the angiogenic tumor vasculature and the extracellular pH. First, Gao and colleagues introduced tertiary amines with controlled hydrophobic substituents as ionizable hydrophobic blocks for the pH-sensitive core. Nanoprobes with different transition pH values can thus be achieved by using tertiary amino groups that protonate at a different pH. Subsequently the polymers were derivatized with hydrophobic fluorophores. At physiological pH, the monomers spontaneously assemble with the fluorophores oriented into the centre of the particle and in close proximity with each other. As a result of this, the fluorophores tend to silence each other by a process called fluorescence resonance energy transfer. As the particle navigates the body and enters the tumor site, the drop in pH begins to protonate the amines. The extremely high sensitivity makes these nanoprobes promising candidates for clinical tumor diagnosis.117181sciescopu
Multi-modal transfection agent based on monodisperse magnetic nanoparticles for stem cell gene delivery and tracking
No full textDirecting the controlled differentiation and tracking of stem cells is essential to achieve successful stem cell therapy. In this work, we describe a multi-modal (MR/optical) transfection agent (MTA) for efficient gene delivery and cell tracking of human mesenchymal stem cells (hMSCs). The MTA was synthesized through a facile two-step approach with 1) ligand exchange of a catechol-functionalized polypeptide (CFP) and 2) chemical immobilization of fluorescence labelled cationic polymer via aminolysis reaction. Cationic polymer-immobilized MTAs with size of ~40nm exhibit greatly enhanced colloidal stability in aqueous solution. In addition, the MTAs were capable of binding DNA molecules for transfection. The MTA/pDNA complex showed relatively good transfection efficiency in hMSCs (compared to the commercial transfection agent, Lipofectamine) and good biocompatibility. MTA-treated hMSCs were successfully visualized after transplantation via MR and optical imaging system over 14 days. These studies highlight the challenges associated with the potential advantages of designing multi-modal nanostructured materials as tools for genetic materials delivery and cell-tracking in stem cell therapy. © 2014 Elsevier Ltd.127281sciescopu
Parallel Comparative Studies on Mouse Toxicity of Oxide Nanoparticle- and Gadolinium-Based T1 MRI Contrast Agents
No full textMagnetic resonance imaging (MRI) contrast agents with high relaxivity are highly desirable because they can significantly increase the accuracy of diagnosis. However, they can be potentially toxic to the patients. In this study, using a mouse model, we investigate the toxic effects and subsequent tissue damage induced by three T1 MRI contrast agents: gadopentetate dimeglumine injection (GDI), a clinically used gadolinium (Gd)-based contrast agent (GBCAs), and oxide nanoparticle (NP)-based contrast agents, extremely small-sized iron oxide NPs (ESIONs) and manganese oxide (MnO) NPs. Biodistribution, hematological and histopathological changes, inflammation, and the endoplasmic reticulum (ER) stress responses are evaluated for 24 h after intravenous injection. These thorough assessments of the toxic and stress responses of these agents provide a panoramic description of safety concerns and underlying mechanisms of the toxicity of contrast agents in the body. We demonstrate that ESIONs exhibit fewer adverse effects than the MnO NPs and the clinically used GDI GBCAs, providing useful information on future applications of ESIONs as potentially safe MRI contrast agents. © 2015 American Chemical Society143461sciescopu
PH-sensitive nanoformulated triptolide as a targeted therapeutic strategy for hepatocellular carcinoma
No full textHepatocellular carcinoma (HCC) has one of the worst prognoses for
survival as it is poorly responsive to both conventional chemotherapy and
mechanism-directed therapy. This results from a lack of therapeutic concentration
in the tumor tissue coupled with the highly toxic off-site effects exhibited by these
compounds. Consequently, we believe the best packaging for holistic therapy for
HCC will involve three components: a potent therapeutic, a rationally designed
drug delivery vehicle to enrich the target site concentration of the drug, and a surface ligand that can enable a greater propensity to internalization by
tumor cells compared to the parenchyma. We screened a library containing hundreds of compounds against a panel of HCC cells and found the natural
product, triptolide, to be more effective than sorafenib, doxorubicin, and daunorubicin, which are the current standards of therapy. However, the potential
clinical application of triptolide is limited due to its poor solubility and high toxicity. Consequently, we synthesized tumor pH-sensitive nanoformulated
triptolide coated with folate for use in an HCC-subpopulation that overexpresses the folate receptor. Our results show triptolide itself can prevent disease
progression, but at the cost of significant toxicity. Conversely, our pH-sensitive nanoformulated triptolide facilitates uptake into the tumor, and specifically
tumor cells, leading to a further increase in efficacy while mitigating systemic toxicity.143441sciescopu
ir Koo Siu Ling de eerste vrouwelijke ingenieur luchtvaart en ruimtevaarttechniek in Nederland
No full textDe eerste vrouw die afstudeerde aan onze faculteit – die destijds ‘Vliegtuigbouwkunde’ heette – was Koo Siu Ling. Ze was een buitenlandse student uit Indonesië van Chinese afkomst. Toen ze zich aanmeldde voor de opleiding vliegtuigbouwkunde haalde dat zowel in Nederland als in Indonesië de krant. Ze begon met haar studie in 1956, toen ze 16 jaar was.Aerospace Structures & Material
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