Kuantum noktacıklarının hücresel etkileşim ve sitotoksisitelerinin araştırılması

TÜBİTAK SBAG Proje01.05.201

Folic acid-conjugated cationic Ag2S quantum dots for optical imaging and selective doxorubicin delivery to HeLa cells

We aim to develop folic acid ( FA)-conjugated cationic Ag2S near-infrared quantum dots (NIRQDs) for the delivery of doxorubicin (DOX) selectively to folate receptor (FR)-positive cancer cells to achieve enhanced drug efficacy and optical tracking in the NIR region. Materials & methods: Cationic Ag2S NIRQDs were decorated with FA using a PEG bridge and loaded with DOX. In vitro studies were performed on FR-positive human cervical carcinoma cells and FR-negative A549 cells. Results: Significantly higher uptake of DOX by human cervical carcinoma cells cells and a greater therapeutic effect along with a strong intracellular optical signal were obtained with DOX-loaded FA-conjugated Ag2S NIRQDs. Conclusion: These Ag2S NIRQDs are promising theranostic nanoparticles for receptor-mediated delivery of DOX with enhanced drug efficacy combined with optical imaging

Layer-by-layer grown electrodes composed of cationic Fe3O4 nanoparticles and graphene oxide nanosheets for electrochemical energy storage devices

Ultrathin electrodes composed of layer-by-layer as-sembled (3-aminopropyl)trimethoxysilane functionalized iron oxidenanoparticles and graphene oxide nanosheets were prepared by a simpleand low-cost dip coating method without using any binders orconductive additives. The thickness of the Fe3O4/GOfilms was simplyaltered with the number of dip coating cycles. Multilayeredfilms werechemically reduced with hydrazine vapor in order to increase theelectrical conductivity. Characterization of multilayerfilms wasperformed with scanning transmission electron microscopy, UV−visspectroscopy, atomic force microscopy, quartz crystal microbalance, X-ray photoelectron spectroscopy, and electron paramagnetic reso-nance spectroscopy. We have performed cyclic voltammetry and electrochemical impedance spectroscopy for the evaluationof Fe3O4/GO multilayers as possible electrochemical capacitor electrodes. Reduced Fe3O4/GOfilms exhibit high specificcapacitances (varying between 200 and 350 F g−1at 5 mV s−1), outperforming the layer-by-layer assembled iron oxides/carbonderivatives (carbon nanotube, graphene)

Anticancer use of nanoparticles as nucleic acid carriers

Commonly used drugs can mainly be classified as protein-based drugs such as insulin and small-molecule chemicals such as aspirin (Acetylsalicylic Acid). Search for organic drug-like molecules with high efficacy and low side-effects revealed nucleic acids as potential drugs. siRNA and miRNAs are one of the negative regulators of gene expression controlling various fundamental biological processes such as cell proliferation, stem cell division, and apoptosis. They act either by altering the stability of the mRNA transcripts and/or blocking protein translation by ribosomes. During the last decade, RNA molecules (siRNA and miRNA) and DNA fragments that code for them (shRNA or miRNA genes) were analyzed in detail to reveal their potential as new generation drugs against cancer. Accumulating data on these drugs will be discussed in the light of recent advances about the usage of nano particles as nucleic acid drug carriers

Urea dimethacrylates functionalized with bisphosphonate/bisphosphonic acid for improved dental materials

Incorporation of bisphosphonate/bisphosphonic acid groups in dental monomer structures should increase interaction of these monomers with dental tissue as these groups have strong affinity for hydroxyapatite. Therefore, new urea dimethacrylates functionalized with bisphosphonate (1a, 1b) and bisphosphonic acid (2a, 2b) groups are synthesized and evaluated for dental applications. Monomers 1a and 1b are synthesized from 2‐isocyanatoethyl methacrylate (IEM) and two bisphosphonated amines (BPA1 and BPA2), prepared as reported elsewhere. Selective dealkylation of the bisphosphonate ester groups of 1a and 1b using trimethylsilyl bromide (TMSBr) gives monomers (2a and 2b) with bisphosphonic acid functionality. X‐ray diffractometer (XRD), Raman spectroscopy, and X‐ray photoelectron spectroscopy (XPS) analyses of monomer‐treated HAP particles show that 2a induces formation of stable monomer‐calcium salts, similar to 10‐methacryloyloxydecyl dihydrogen phosphate (MDP), with higher chemical interaction than 2b. The photopolymerization studies indicate good copolymerizability with commercial dental monomers. In vitro studies on NIH 3T3 mouse embryonic fibroblast cells have clearly shown that the tested monomers (1b and 2b) are not toxic according to the MTT standards. All these properties make these monomers suitable as biocompatible cross‐linkers/adhesives for dental applications

Highly luminescent and cytocompatible cationic Ag2S NIR-emitting quantum dots for optical imaging and gene transfection

The development of non-toxic theranostic nanoparticles capable of delivering a therapeutic cargo and providing a means for diagnosis is one of the most challenging tasks in nano-biotechnology. Gene therapy is a very important mode of therapy and polyethyleneimine (PEI) is one of the most successful vehicles for gene transfection, yet poses significant toxicity. Optical imaging utilizing quantum dots is one of the newer but fast growing diagnostic modalities, which requires non-toxic, highly luminescent materials, preferentially active in the near infrared region. Ag2S NIRQDs fit to this profile perfectly. Here, we demonstrate the aqueous synthesis of cationic Ag2S NIRQDs with a mixed coating of 2-mercapto- propionic acid (2MPA) and PEI (branched, 25 kDa), which are highly luminescent in the NIR-I window (λem = 810–840 nm) as new theranostic nanoparticles. Synergistic stabilization of the QD surface via the simultaneous use of a small molecule and a polymeric material provided the highest quantum yield, 150% (with respect to LDS 798 at pH 7.4), reported in the literature for Ag2S. These cationic particles show a dramatic improvement in cytocompatibility even without PEGylation, a strong optical signal easily detected by confocal laser microscopy and effective conjugation and transfection of the green fluo- rescence protein plasmid (pGFP) to HeLa and MCF-7 cell lines (40% efficiency). Overall, these Ag2S NIRQDs show great potential as new theranostics

Development of tailored SPION-PNIPAM nanoparticles by ATRP for dually responsive doxorubicin delivery and MR imaging

Biocompatible, colloidally stable and ultra-small Fe3O4 nanoparticles (SPIONs) coated with poly(N-isopropyl-acrylamide) (PNIPAM) were synthesized via surface-initiated ATRP (atom transfer radical polymerization) to prevent excessive aggregation of magnetic cores and interparticle crosslinking, and to provide control over polymer content. These SPION-PNIPAM nanoparticles (NPs) have a hydrodynamic size between 8 and 60 nm depending on the PNIPAM content, and hence are ultrasmall in size and have an LCST around 38 degrees C. They had a high drug-loading capacity reaching 9.6 wt% doxorubicin in the final composition. The Dox release studies revealed pH and temperature-dependent release, which was not reported for PNIPAM before. Release of Dox under physiological conditions was below 20%, but around 90% at 42 degrees C and pH 5. This dually responsive nature is very advantageous to increase the drug efficacy and reduce side-effects, simultaneously. The cytocompatability of the SPION-PNIPAM NPs and the influence of Dox delivery to cells were investigated via in vitro cell viability, apoptosis, DNA-damage and confocal microscopy studies. The NPs were shown to be highly cytocompatible and induce significant cell death due to Dox when loaded with the drug. Besides, it was seen that the polymeric content can be used as an additional factor in tuning the release kinetics. Lastly, these nanoparticles reduced the signal intensity significantly in the T2 mode, acting as a potential SPION-based contrast agent. Overall, here, we demonstrate the design of small, smart theranostic nanoparticles with high drug-loading capacity and pH-dependent temperature-sensitive release characteristics with the ability to generate contrast in MRI

Magnetic nanoparticle based nanofluid actuation with dynamic magnetic fields

Magnetic nanoparticle suspensions and their manipulation are becoming an alternative research line and have very important applications in the field of microfluidics such as microscale flow control in microfluidic circuits, actuation of fluids in microscale, and drug delivery mechanisms. In microscale, it is possible and beneficial to use magnetic fields as actuators of such nanofluids, where these fluids could move along a gradient of magnetic field so that a micropump without any moving parts could be generated with this technique. Thus, magnetically actuated nanofluids could have the potential to be used as an alternative micro pumping system. Actuation of ferrofluid plugs with a changing magnetic field has been extensively studied in the literature. However; the flow properties of ferrofluids are sparsely investigated when the ferrofluid itself is forced to continuously flow inside a channel. As an extension of previous studies, this study aims to investigate flows of magnetic nanoparticle based nanofluids by a generated magnetic field and to compare the efficiency of the resulting system. Lauric Acid coated Super Paramagnetic Iron Oxide (SPIO-LA) was used as the ferrofluid sample in the experiments to realise actuation. Significant flow rates up to 61.8 mu L/s at nominal maximum magnetic field strengths of 300mT were achieved in the experiments. Results suggest that nanofluids with magnetic nanoparticles merit more research efforts in micro pumping. Thus, magnetic actuation could be a significant alternative for more common techniques such as electromechanical, electrokinetic, and piezoelectric actuation

Discovery of an exceptionally strong luminescence of polyethyleneimine-superparamagnetic iron oxide nanoparticles

Polyethyleneimine (PEI) is rarely recognized as a luminescent polymer but is frequently used for the production of cationic nanoparticles and tagged with an organic fluorophore to be tracked optically. Herein, a strongly luminescent, branched PEI-superparamagnetic iron oxide nanoparticle (bPEI-SPION) without a traditional fluorophore is reported. A tremendous enhancement (1200 times) in the weak blue luminescence of bPEI is achieved only if it is adsorbed on a SPION during the synthesis of nanoparticles, which is improved further upon protonation, irreversibly. This is quite unexpected since SPIONs are strong absorbers in the visible region. All reaction parameters, different synthetic methods, as well as protonation are studied as independent factors to understand the origin of such enhancement. Detailed spectroscopic analysis and density functional theory calculations indicate that partial amine oxidation and Fe3+ reduction takes place during the synthesis, which significantly contributes to the luminescence enhancement. In addition, PEI-SPION exhibits excitation wavelength dependent emission and maintains its magnetic properties