Electrostatic droplets assisted in situ synthesis of superparamagnetic chitosan microparticles for magnetic-responsive controlled drug release and copper ion removal

This paper demonstrates a facile approach for the in situ synthesis of size-controllable superparamagnetic chitosan micro-beads with a saturation magnetization value as high as ca. 35.3 emu g^-1 at room temperature. The proposed process utilized the electrostatic droplets (ESD) technique, which is quite effective in producing uniform-sized polymer beads. A sodium hydroxide solution was employed for both the solidification of chitosan and the co-precipitation of ferro-gels containing both ferrous and ferric cations. The diameter of the beads was very uniform (each relative standard deviation was below 3.4%) and adjustable from 84 μm to ca. 555 μm by varying the electrostatic field. Cell viability tests indicated that the superparamagnetic chitosan particles were eco-friendly and had a high potential for biological applications. The results show that the superparamagnetic chitosan particles achieved superior results in magnetic-responsive drug release as well as heavy metal removal (e.g. copper ions). This study demonstrated that the appropriate magnetic field intensity for different release patterns is predictable, which allows for better application of microcapsules as a smart drug carrier. In addition, the proposed chitosan particles serve as an alternative material for the adsorption of heavy metal ions from contaminated industrial effluents, while their superparamagnetic properties are advantageous in that they make the chitosan particles guidable by an external magnetic field.

The relationship between body mass index and quality of life in community-living older adults living in the United States

BACKGROUND

Carrying excess weight is associated with various chronic conditions especially in older adults, and can have a negative influence on the quality of life of this population.

OBJECTIVE

The objective of this study was to estimate the independent (i.e. adjusted for demographic, socioeconomic and health status differences) impact of Body Mass Index (BMI) on health-related quality of life.

DESIGN

A mail survey was sent to 60,000 older adults living in 10 states.

METHODS

The survey assessed quality of life using the average physical component scores (PCS) and mental component scores (MCS) obtained from the Veterans Rand 12-item (VR-12) health status tool embedded in the survey. Ordinary least squares (OLS) regression techniques were used to estimate the independent impact of each BMI category on quality of life, compared to the impact of other chronic conditions.

RESULTS

A total of 22,827 (38%) eligible sample members responded to the survey. Of those, 2.2% were underweight, 38.5% had a normal BMI, 37.0% were overweight, 18.5% were obese and 1.9% were morbidly obese. Following OLS regression techniques, respondents' PCS values were statistically significantly lower for the underweight, overweight, obese and morbidly obese BMI categories, compared to the normal BMI group. Compared with all other chronic conditions, being morbidly obese (-6.0 points) had the largest negative impact on the PCS. Underweight was the only BMI category with a statistically significantly lower MCS value.

CONCLUSIONS

The greatest negative impacts of the various BMI categories on quality of life were on physical rather than mental aspects, especially for those in the underweight, obese and morbidly obese categories, more so than many other chronic conditions.

Facile synthesis of radial-like macroporous superparamagnetic chitosan spheres with in-situ co-precipitation and gelation of ferro-gels

Macroporous chitosan spheres encapsulating superparamagnetic iron oxide nanoparticles were synthesized by a facile and effective one-step fabrication process. Ferro-gels containing ferrous cations, ferric cations and chitosan were dropped into a sodium hydroxide solution through a syringe pump. In addition, a sodium hydroxide solution was employed for both gelation (chitosan) and co-precipitation (ferrous cations and ferric cations) of the ferro-gels. The results showed that the in-situ co-precipitation of ferro-ions gave rise to a radial morphology with non-spheroid macro pores (large cavities) inside the chitosan spheres. The particle size of iron oxide can be adjusted from 2.5 nm to 5.4 nm by tuning the concentration of the sodium hydroxide solution. Using Fourier Transform Infrared Spectroscopy and X-ray diffraction spectra, the synthesized nanoparticles were illustrated as Fe₃O₄ nanoparticles. In addition, the prepared macroporous chitosan spheres presented a super-paramagnetic behaviour at room temperature with a saturation magnetization value as high as ca. 18 emu/g. The cytotoxicity was estimated using cell viability by incubating doses (0∼1000 µg/mL) of the macroporous chitosan spheres. The result showed good viability (above 80%) with alginate chitosan particles below 1000 µg/mL, indicating that macroporous chitosan spheres were potentially useful for biomedical applications in the future.

Nucleocytoplasmic transport blockage by SV40 peptide-modified gold nanoparticles induces cellular autophagy

Gold nanoparticles modified with the nuclear localization signal from simian virus 40 large T antigen (GNP-PEG/SV40) accumulate on the cytoplasmic side of the nuclear membrane in HeLa cells. Accumulation of GNP-PEG/SV40 around the nucleus blocks nucleocytoplasmic transport and prevents RNA export and nuclear shuttling of signaling proteins. This long-term blockage of nucleocytoplasmic transport results in cell death. This cell death is not caused by apoptosis or necrosis because caspases 3 and 9 are not activated, and the expression of annexin V/propidium iodide is not enhanced in HeLa cells after treatment. Using transmission electron microscopy, autophagosomes and autolysosomes were seen to appear after 72 hours of treatment with GNP-PEG/SV40. Increasing levels of enhanced green fluorescent protein-microtubule-associated protein 1 light chain 3 (EGFP-LC3)-positive punctate and LC3-II confirmed GNP-PEG/SV40-induced autophagy. In SiHa cells, treatment did not induce accumulation of GNP-PEG/SV40 around the nucleus and autophagy. Treating cells with wheat germ agglutinin, a nuclear pore complex inhibitor, induced autophagy in both HeLa and SiHa cells. GNP-PEG/SV40-induced autophagy plays a role in cell death, not survival, and virus-mediated small hairpin RNA silencing of Beclin-1 attenuates cell death. Taken together, the results indicate that long-term blockade of nucleocytoplasmic transport results in autophagic cell death.

PLGA nanoparticles codeliver paclitaxel and Stat3 siRNA to overcome cellular resistance in lung cancer cells

BACKGROUND

Effective cancer chemotherapy remains an important issue in cancer treatment, and signal transducer and activator of transcription-3 (Stat3) activation leads to cellular resistance of anticancer agents. Polymers are ideal vectors to carry both chemotherapeutics and small interfering ribonucleic acid (siRNA) to enhance antitumor efficacy. In this paper, poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with paclitaxel and Stat3 siRNA were successfully synthesized, and their applications in cancer cells were investigated.

METHODS

Firstly, paclitaxel was enclosed by PLGA nanoparticles through solvent evaporation. They were then coated with cationic polyethylenimine polymer (PLGA-PEI-TAX), enabling it to carry Stat3 siRNA on its surface through electrostatic interactions (PLGA-PEI-TAX-S3SI). The size, zeta potential, deliver efficacy, and release profile of the PLGA nanocomplexes were characterized in vitro. The cellular uptake, intracellular nanoparticle trajectory, and subsequent cellular events were evaluated after treatment with various PLGA nanocomplexes in human lung cancer A549 cells and A549-derived paclitaxel-resistant A549/T12 cell lines with α-tubulin mutation.

RESULTS

A549 and A549/T12 cells contain constitutively activated Stat3, and silencing Stat3 by siRNA made both cancer cells more sensitive to paclitaxel. Therefore, PLGA-PEI-TAX-S3SI was synthesized to test its therapeutic role in A549 and A549/T12 cells. Transmission electron microscopy showed the size of PLGA-PEI-TAX-S3SI to be around 250 nm. PLGA-PEI nanoparticles were nontoxic. PLGA-PEI-TAX was taken up by A549 and A549/T12 cells more than free paclitaxel, and they induced more condensed microtubule bundles and had higher cytotoxicity in these cancer cells. Moreover, the yellowish fluorescence observed in the cytoplasm of the cancer cells indicates that the PLGA-PEI nanoparticles were still simultaneously delivering Oregon Green paclitaxel and cyanine-5-labeled Stat3 siRNA 3 hours after treatment. Furthermore, after the cancer cells were incubated with the synthesized PLGA nanocomplexes, PLGA-PEI-TAX-S3SI suppressed Stat3 expression and induced more cellular apoptosis in A549 and A549/T12 cells compared with PLGA-PEI-TAX.

CONCLUSION

The PLGA-PEI-TAX-S3SI complex provides a new therapeutic strategy to control cancer cell growth.

Near-infrared light-responsive intracellular drug and siRNA release using au nanoensembles with oligonucleotide-capped silica shell

Taking advantage of the character of Au nanorods (NRs) to absorb NIR light, a NIR-responsive oligonucleotide-gated ensemble is developed to perform intracellular drug delivery. Using an oligonucleotide bio-gate enables siRNA release into cells for translational regulation as well as cytotoxicity in anti-cancer drug delivery.

Formation of Ag nanoframes with facilitation of dithiols

Two-dimensional Ag nanoprisms readily formed Ag triangular nanoframes upon electron beam irradiation. Following meso-2, 3-dimercaptosuccinicacid (DMSA) ripening behavior, continuous electron beam exposure transformed a solid nanoplate into a core/void/shell morphology, which then evolved into a hollow nanoframe structure. TEM was used to observe the ripening and etching processes of Ag nanoprisms as a function of DMSA concentration and electron irradiation time. X-ray diffraction (XRD) and FT-IR analysis were conducted to characterize the Ag nanoprism structure and surface before and after treatment with DMSA. X-ray photoelectron spectroscopy (XPS) was used to determine surface chemical compositions and indicated DMSA was adsorbed on the Ag nanoprisms in the form of Ag(+)-S(-). Raman measurements provided evidence of a disulfide group on Ag nanoprisms. Similar organosulfur structures such as mercaptosuccinic acid and 2-mercaptoacetic acid were also studied with results suggesting that the two S-H groups of dithiol DMSA played the crucial role in nanoframe fabrication. Using the same strategy with DMSA, the nano-architecture can be extended to 2D nanodiscs yielding nanorings.

Reversible synthesis of sub-10 nm spherical and icosahedral gold nanoparticles from a covalent Au(CN)2(-) precursor and recycling of cyanide to form ferric ferrocyanide for cell staining

A solution approach based on Au(CN)(2)(-) chemistry is reported for the formation of nanoparticles. The covalent character of the Au(CN)(2)(-) precursor was exploited in the formation of sub-10 nm nanospheres (≈2.4 nm) and highly monodisperse icosahedral Au nanoparticles (≈8 nm) at room temperature in a one-pot aqueous synthesis. The respective spherical and icosahedral Au morphologies can be controlled by either the absence or presence of the polymer polyvinylpyrrolidone (PVP). Using Au(CN)(2)(-) as a metal ion source, our findings suggest that the addition of citrate ions is necessary to enhance the particle formation rate as well as to generate a more homogeneous colloidal dispersion. Because of the presence of oxygen and the operation of a CN(-) etching process associated with Au(CN)(2)(-) complex formation, an interesting reversible formation-dissolution process was observed, which allowed us to repeatedly prepare spherical and icosahedral Au nanoparticles. Time-dependent TEM images and UV/Vis spectra were carefully acquired to study the reversibility of this formation-dissolution process. In view of the accompanying generation of toxic cyanide anions, we have developed a protocol to recycle cyanide in the presence of citrate ions through ferric ferrocyanide formation. After completion of particle formation, the residual solutions containing citrate ions and cyanide ions were processed to stain iron oxide nanoparticles endocytosized in cells. Additionally, the as-prepared 8 nm Au icosahedra could be isolated and grown to larger 57 nm-sized icosahedra using the seed-mediated growth approach.

Size-dependent attenuation of TLR9 signaling by gold nanoparticles in macrophages

Gold nanoparticles (GNPs), which are generally thought to be bio-inert and non-cytotoxic, have become one of the most ideal nanomaterials for medical applications. Once engulfed by phagocytes, the immunological effects of GNPs are still of concern and require detailed investigation. Therefore, this study explored the immunological significance of GNPs on TLR-mediated innate immunity in murine macrophages. GNP causes specific inhibition of TLR9 (CpG oligodeoxynucleotides; CpG-ODNs) signal in macrophages. The impaired CpG-ODN-induced TNF-α production is GNP concentration- and size-dependent in murine Raw264.7 cells: a GNP of 4 nm in size is more potent than a GNP of 11, 19, 35, or 45 nm in size. Consistent with cytokine inhibition, the CpG-ODN-induced phosphorylation of NF-κB and JNK as well as NF-κB activation are suppressed by GNPs. GNPs accumulate in lysosomes after phagocytosis and also increase TLR9-associated lysosomal cathepsin expression and activities, but this is irrelevant to TLR9 inhibition by GNPs in our studies. In addition, GNPs affected TLR9 translocation in response to CpG-ODNs and to phagosomes. Further exploring how GNPs inhibited TLR9 function, we found that GNPs could bind to high-mobility group box-1 (which is involved in the regulation of TLR9 signaling) inside the lysosomes. The current studies demonstrate that size-dependent inhibition of TLR9 function by GNP may be attributed to its binding to high-mobility group box-1.

A thermolysis approach to simultaneously achieve crystal phase- and shape-control of ternary M-Fe-O metal oxide nanoparticles

Significant studies have achieved beautiful control in particle size, while the shape- and phase-control synthesis of nanoparticles remains an open challenge. In this study, we have developed a generalized methodology to selectively prepare either NaCl-type (reduced form) or spinel-type ferrite (oxidized form) M-Fe-O (M = Mn, Co) crystallites with high reproducibility. A two-step heating process was able to control formation of two types of crystal phase, either a thermodynamic spinel-type under air or a kinetic-control of NaCl-type (rock salt structure) under Ar in a cubic morphology. On the other hand, the three-step heating procedure in air obtained the spinel-type with a thermodynamic equilibrium octahedral shape exclusively. Either using metal acetates (M(ac)(2)) or metal acetylacetonates (M(acac)(2)) as the starting precursors (M = Mn, Co) can be introduced to prepare NaCl-type (reduced form) or spinel-type ferrite (oxidized form) crystallites with identical experimental parameters, including precursor concentration, reaction temperature, reaction time, and heating rate. The oleic acid molecule, reaction temperature, and heating rate employed in the synthesis were carefully examined and found acting as determined roles behind the reaction processes. Apart from the previous literature reports as shape-directed and/or stabilizing agents, the oleic acid molecule played an additional phase-tuning role.

Enhancing transversal relaxation for magnetite nanoparticles in MR imaging using Gd³+- chelated mesoporous silica shells

A new magnetic nanoparticle was synthesized in the form of Gd(3+)-chelated Fe(3)O(4)@SiO(2). The Fe(3)O(4) nanoparticle was octahedron-structured, was highly magnetic (∼94 emu/g), and was the core of an encapsulating mesoporous silica shell. DOTA-NHS molecules were anchored to the interior channels of the porous silica to chelate Gd(3+) ions. Because there were Gd(3+) ions within the silica shell, the transverse relaxivity increased 7-fold from 97 s(-1) mM(-1) of Fe(3)O(4) to 681 s(-1) mM(-1) of Gd(3+)-chelated Fe(3)O(4)@SiO(2) nanoparticles with r(2)/r(1) = 486. The large transversal relaxivity of the Gd(3+)-chelated Fe(3)O(4)@SiO(2) nanoparticles had an effective magnetic resonance imaging effect and clearly imaged lymph nodes. Physiological studies of liver, spleen, kidney, and lung tissue in mice infused with these new nanoparticles showed no damage and no cytotoxicity in Kupffer cells, which indicated that Gd(3+)-chelated Fe(3)O(4)@SiO(2) nanoparticles are biocompatible.