Pt-containing nanoscale coordination polymer (NCP) particles with the formula of Tb2(DSCP)3(H2O)12 (where DSCP represents disuccinatocisplatin), NCP-1, were precipitated from an aqueous solution of ...Tb3+ ions and DSCP bridging ligands via the addition of a poor solvent. SEM and TEM images showed that as-synthesized NCP-1 exhibited a spherical morphology with a DLS diameter of 58.3 ± 11.3 nm. NCP-1 particles were stabilized against rapid dissolution in water by encapsulation in shells of amorphous silica. The resulting silica-coated particles NCP-1′ exhibited significantly longer half-lives for DSCP release from the particles (a t 1/2 of ∼9 h for NCP-1′ with 7 nm silica coating vs t 1/2 of ∼1 h for as-synthesized NCP-1). In vitro cancer cell cytotoxicity assays with the human colon carcinoma cell line (HT-29) showed that internalized NCP-1′ particles readily released the DSCP moieties which were presumably reduced to cytotoxic Pt(II) species to give the Pt-containing NCPs anticancer efficacy superior to the cisplatin standard. The generality of this degradable nanoparticle formulation should allow for the design of NCPs as effective delivery vehicles for a variety of biologically and medically important cargoes such as therapeutic and imaging agents.
Fe(III)-carboxylate nanoscale metal−organic frameworks (NMOFs) with the MIL-101 structure were synthesized using a solvothermal technique with microwave heating. The ∼200 nm particles were ...characterized using a variety of methods, including SEM, PXRD, nitrogen adsorption measurements, TGA, and EDX. By replacing a percentage of the bridging ligand (terephthalic acid) with 2-amino terephthalic acid, amine groups were incorporated into the framework to provide sites for covalent attachment of biologically relevant cargoes while still maintaining the MIL-101 structure. In proof-of-concept experiments, an optical contrast agent (a BODIPY dye) and an ethoxysuccinato-cisplatin anticancer prodrug were successfully incorporated into the Fe(III)-carboxylate NMOFs via postsynthetic modifications of the as-synthesized particles. These cargoes are released upon the degradation of the NMOF frameworks, and the rate of cargo release was controlled by coating the NMOF particles with a silica shell. Potential utility of the new NMOF-based nanodelivery vehicles for optical imaging and anticancer therapy was demonstrated in vitro using HT-29 human colon adenocarcinoma cells.
Less basic: By controlling the pH value of the reaction medium, two different gadolinium‐containing nanoscale metal–organic frameworks (NMOFs) based on the same building blocks can be synthesized ...(see picture). The NMOFs carry a large payload of Gd3+ centers and are efficient contrast agents for T2‐weighted magnetic resonance imaging. The NMOFs are highly luminescent when doped with other lanthanide ions such as Eu and Tb.
The coordination‐directed assembly of metal ions and organic bridging ligands has afforded a variety of bulk‐scale hybrid materials with promising characteristics for a number of practical ...applications, such as gas storage and heterogeneous catalysis. Recently, so‐called coordination polymers have emerged as a new class of hybrid nanomaterials. Herein, we highlight advances in the syntheses of both amorphous and crystalline nanoscale coordination polymers. We also illustrate how scaling down these materials to the nano‐regime has enabled their use in a broad range of applications including catalysis, spin‐crossover, templating, biosensing, biomedical imaging, and anticancer drug delivery. These results underscore the exciting opportunities of developing next‐generation functional nanomaterials based on molecular components.
Next‐generation nanomaterials: The coordination‐directed assembly of metal ions and organic bridging ligands has afforded bulk‐scale functional hybrid materials. Their scaling‐down to the nano‐regime has led to nanoscale coordination polymers and metal–organic frameworks which have been used in a broad range of applications including catalysis, spin‐crossover, templating, biosensing, biomedical imaging, and anticancer drug delivery.
Hybrid nanomaterials for biomedical applications Taylor-Pashow, Kathryn M. L; Della Rocca, Joseph; Huxford, Rachel C ...
Chemical communications (Cambridge, England),
08/2010, Letnik:
46, Številka:
32
Journal Article
Recenzirano
Hybrid nanomaterials, composed of both inorganic and organic components, have recently been examined as promising platforms for imaging and therapeutic applications. This unique class of ...nanomaterials can not only retain beneficial features of both the inorganic and organic components, but also provides the ability to systematically tune the properties of the hybrid material through the combination of functional components. This
feature article
will summarize recent advances in the design and synthesis of hybrid nanomaterials and their applications in biological and biomedical areas. The hybrid nanomaterials to be discussed fall into two main categories, silica based materials and nanoscale metal-organic frameworks. Their applications as imaging contrast agents and nanotherapeutics will be highlighted.
This
feature article
highlights recent advances in the design and synthesis of hybrid nanomaterials-silica based materials and nanoscale metal-organic frameworks, and their applications as imaging contrast agents and nanotherapeutics.
We describe in this paper a general method for synthesizing a new class of nanocomposites with a nanoscale metal-organic framework (NMOF) core and a silica shell. Silica shells of variable thickness ...were deposited on the NMOFs that had been surface-modified with polyvinylpyrrolidone (PVP) using a sol−gel procedure. The NMOF core of the nanocomposite could be completely removed (via dissolution) at low pH to afford hollow silica shells with varied thickness and aspect ratios. We also showed that the silica shell of such nanocomposites significantly stabilized the NMOF core against dissolution, thus demonstrating the ability to control the release of metal constituents from such silica-coated NMOFs. The silica shell was further functionalized with a silylated Tb-EDTA monoamide derivative for the luminescence sensing of dipicolinic acid (DPA), which is a major constituent of many pathogenic spore-forming bacteria. Owing to the tunability of NMOF composition and morphology, the present approach should allow for the synthesis of not only interesting nanoshells that are not accessible with presently available templates but also novel core−shell hybrid nanostructures for future imaging, sensing, and drug delivery applications.
Nanoscale metal−organic frameworks (NMOFs) based on Gd3+ centers and benzenedicarboxylate and benzenetricarboxylate bridging ligands were synthesized using reverse microemulsions and characterized ...using SEM, PXRD, and TGA. These NMOFs exhibit extraordinarily large R1 and R2 relaxivities because of the presence of up to tens of millions of Gd3+ centers in each nanoparticle and are thus efficient T1 and T2 contrast agents for MRI. The NMOFs can also be made highly luminescent by doping with Eu3+ or Tb3+ centers. The results from this work suggest that NMOFs can be used as potential contrast agents for multimodal imaging.
Manganese-containing nanoscale metal−organic frameworks (NMOFs) with controllable morphologies were synthesized using reverse-phase microemulsion techniques at room temperature and a ...surfactant-assisted procedure at 120 °C with microwave heating. The nanoparticles were characterized using a variety of methods including SEM, TEM, TGA, PXRD, and ICP−MS. Although the nanoparticles gave a modest longitudinal relaxivity (r 1) on a per Mn basis, they provided an efficient vehicle for the delivery of large doses of Mn2+ ions which exhibited very high in vitro and in vivo r 1 values and afforded excellent MR contrast enhancement. The particle surface was also modified with a silica shell to allow covalent attachment of a cyclic RGD peptide and an organic fluorophore. The cell-targeting molecules on the Mn NMOFs enhanced their delivery to cancer cells to allow for target-specific MR imaging in vitro. The MR contrast enhancement was also demonstrated in vivo using a mouse model. Such core−shell hybrid nanostructures provide an ideal platform for targeted delivery of other imaging and therapeutic agents to diseased tissues.
Background
Low-volume high-intensity interval training (HIT) appears to be an efficient and practical way to develop physical fitness.
Objective
Our objective was to estimate meta-analysed mean ...effects of HIT on aerobic power (maximum oxygen consumption
V
O
2max
in an incremental test) and sprint fitness (peak and mean power in a 30-s Wingate test).
Data Sources
Five databases (PubMed, MEDLINE, Scopus, BIOSIS and Web of Science) were searched for original research articles published up to January 2014. Search terms included ‘high intensity’, ‘HIT’, ‘sprint’, ‘fitness’ and ‘
V
O
2max
’.
Study Selection
Inclusion criteria were fitness assessed pre- and post-training; training period ≥2 weeks; repetition duration 30–60 s; work/rest ratio <1.0; exercise intensity described as maximal or near maximal; adult subjects aged >18 years.
Data Extraction
The final data set consisted of 55 estimates from 32 trials for
V
O
2max
, 23 estimates from 16 trials for peak sprint power, and 19 estimates from 12 trials for mean sprint power. Effects on fitness were analysed as percentages via log transformation. Standard errors calculated from exact
p
values (where reported) or imputed from errors of measurement provided appropriate weightings. Fixed effects in the meta-regression model included type of study (controlled, uncontrolled), subject characteristics (sex, training status, baseline fitness) and training parameters (number of training sessions, repetition duration, work/rest ratio). Probabilistic magnitude-based inferences for meta-analysed effects were based on standardized thresholds for small, moderate and large changes (0.2, 0.6 and 1.2, respectively) derived from between-subject standard deviations (SDs) for baseline fitness.
Results
A mean low-volume HIT protocol (13 training sessions, 0.16 work/rest ratio) in a controlled trial produced a likely moderate improvement in the
V
O
2max
of active non-athletic males (6.2 %; 90 % confidence limits ±3.1 %), when compared with control. There were possibly moderate improvements in the
V
O
2max
of sedentary males (10.0 %; ±5.1 %) and active non-athletic females (3.6 %; ±4.3 %) and a likely small increase for sedentary females (7.3 %; ±4.8 %). The effect on the
V
O
2max
of athletic males was unclear (2.7 %; ±4.6 %). A possibly moderate additional increase was likely for subjects with a 10 mL·kg
−1
·min
−1
lower baseline
V
O
2max
(3.8 %; ±2.5 %), whereas the modifying effects of sex and difference in exercise dose were unclear. The comparison of HIT with traditional endurance training was unclear (−1.6 %; ±4.3 %). Unexplained variation between studies was 2.0 % (SD). Meta-analysed effects of HIT on Wingate peak and mean power were unclear.
Conclusions
Low-volume HIT produces moderate improvements in the aerobic power of active non-athletic and sedentary subjects. More studies are needed to resolve the unclear modifying effects of sex and HIT dose on aerobic power and the unclear effects on sprint fitness.
Intervention fidelity refers to the degree to which an experimental manipulation has been implemented as intended, but simple, robust methods for quantifying fidelity have not been well documented. ...Therefore, we aim to illustrate a rigorous quantitative evaluation of intervention fidelity, using data collected during a high-intensity interval training intervention.
Single-group measurement study.
Seventeen adolescents (mean age ± standard deviation SD 14.0 ± 0.3 years) attended a 10-week high-intensity interval training intervention, comprising two exercise sessions per week. Sessions consisted of 4-7 45-s maximal effort repetitions, interspersed with 90-s rest. We collected heart rate data at 5-s intervals and recorded the peak heart rate for each repetition. The high-intensity exercise criterion was ≥ 90% of individual maximal heart rate. For each participant, we calculated the proportion of total exercise repetitions exceeding this threshold. A linear mixed model was applied to properly separate the variability in peak heart rate between- and within-subjects. Results are presented both as intention to treat (including missed sessions) and per protocol (only participants with 100% attendance; n=8).
For intention to treat, the median (interquartile range) proportion of repetitions meeting the high-intensity criterion was 58% (42% to 68%). The mean peak heart rate was 85% of maximal, with a between-subject SD of 7.8 (95% confidence interval 5.4 to 11.3) percentage points and a within-subject SD of 15.1 (14.6 to 15.6) percentage points. For the per protocol analysis, the median proportion of high-intensity repetitions was 68% (47% to 86%). The mean peak heart rate was 91% of maximal, with between- and within-subject SDs of 3.1 (-1.3 to 4.6) and 3.4 (3.2 to 3.6) percentage points, respectively.
Synthesising information on exercise session attendance and compliance (exercise intensity) quantifies the intervention dose and informs evaluations of treatment fidelity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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