Development of handheld induction heaters for magnetic fluid hyperthermia applications andin-vitroevaluation on ovarian and prostate cancer cell lines.

Objective:Magnetic fluid hyperthermia (MFH) is a still experimental technique found to have a potential application in the treatment of cancer. The method aims to reach around 41 °C-47 °C in the tumor site by exciting magnetic nanoparticles with an externally applied alternating magnetic field (AMF), where cell death is expected to occur. Applying AMFs with high spatial resolution is still a challenge. The AMFs from current and prospective MFH applicators cover relatively large areas; being not suitable for patients having metallic implants near the treatment area. Thus, there will be a clinical need for smaller magnetic field applicators. To this end, a laparoscopic induction heater (LIH) and a transrectal induction heater (TRIH) were developed.Methods:Miniature 'pancake' coils were wound and inserted into 3D printed enclosures. Ovarian (SKOV-3, A2780) and prostate (PC-3, LNCaP) cancer cell lines were used to evaluate the instruments' capabilities in killing cancer cellsin vitro, using Synomag®-D nanoparticles as the heat mediators. NIH3T3 normal cell lines were also used with both devices to observe if these cells tolerated the conditions applied.Results:Magnetic field intensities reached by the LIH and TRIH were 42.6 kA m-1at 326 kHz and 26.3 kA m-1at 303 kHz, respectively. Temperatures reached in the samples were 41 °C by the LIH and 43 °C by the TRIH. Both instruments successfully accomplished killing cancer cells, with minimal effects on normal cells.Conclusion:This work presents the first line of handheld medical induction heaters and have the potential to be a complement to existing cancer therapies.Significance:These instruments could enable the development of MFH modalities that will facilitate the clinical translation of this thermal treatment.

Measuring advertising effectiveness in Travel 2.0 websites through eye-tracking technology.

The advent of Web 2.0 is changing tourists' behaviors, prompting them to take on a more active role in preparing their travel plans. It is also leading tourism companies to have to adapt their marketing strategies to different online social media. The present study analyzes advertising effectiveness in social media in terms of customers' visual attention and self-reported memory (recall). Data were collected through a within-subjects and between-groups design based on eye-tracking technology, followed by a self-administered questionnaire. Participants were instructed to visit three Travel 2.0 websites (T2W), including a hotel's blog, social network profile (Facebook), and virtual community profile (Tripadvisor). Overall, the results revealed greater advertising effectiveness in the case of the hotel social network; and visual attention measures based on eye-tracking data differed from measures of self-reported recall. Visual attention to the ad banner was paid at a low level of awareness, which explains why the associations with the ad did not activate its subsequent recall. The paper offers a pioneering attempt in the application of eye-tracking technology, and examines the possible impact of visual marketing stimuli on user T2W-related behavior. The practical implications identified in this research, along with its limitations and future research opportunities, are of interest both for further theoretical development and practical application.

Enhanced proteotoxic stress: one of the contributors for hyperthermic potentiation of the proteasome inhibitor bortezomib using magnetic nanoparticles.

The induction of hyperthermia using nanoparticles, known as magnetic fluid hyperthermia (MFH) in combination with anti-cancer drugs is an attractive method because of the potential for enhanced anti-cancer effects. Recent studies have shown that cells treated with MFH are more sensitive to the proteasome inhibitor bortezomib (BZ) than cells treated by hot water hyperthermia (HWH) under the same temperature conditions. We hypothesized that enhanced proteotoxic stress, caused by a combination of microtubule damage and an increase in the amount of aggregated proteins, may be partially responsible for this observation. To test this hypothesis MCF-7 cells were exposed to hyperthermic treatment (MFH or HWH) at 43 °C or 45 °C for 30 minutes. Then, aggresome formation and microtubule disruption studies at 30 minutes or 2.5 hours of recovery time were performed to evaluate the progressive effects induced by the two treatments. Cell viability at short and long times was evaluated. Aggresome formation and microtubule disruption results suggested that one of the mechanisms by which MFH enhances BZ cytotoxicity is the formation and subsequent accumulation of aggregated proteins in the cytosol due to the interruption of their transport to the perinuclear area through microtubules. Our data show evidence that MFH induces a more toxic and unmitigated proteotoxic stress than HWH under similar temperature conditions.

Use of Cross-Linked Poly(ethylene glycol)-Based Hydrogels for Protein Crystallization.

Poly(ethylene glycol) (PEG) hydrogels are highly biocompatible materials extensively used for biomedical and pharmaceutical applications, controlled drug release, and tissue engineering. In this work, PEG cross-linked hydrogels, synthesized under various conditions, were used to grow lysozyme crystals by the counterdiffusion technique. Crystallization experiments were conducted using a three-layer arrangement. Results demonstrated that PEG fibers were incorporated within lysozyme crystals controlling the final crystal shape. PEG hydrogels also induced the nucleation of lysozyme crystals to a higher extent than agarose. PEG hydrogels can also be used at higher concentrations (20-50% w/w) as a separation chamber (plug) in counterdiffusion experiments. In this case, PEG hydrogels control the diffusion of the crystallization agent and therefore may be used to tailor the supersaturation to fine-tune crystal size. As an example, insulin crystals were grown in 10% (w/w) PEG hydrogel. The resulting crystals were of an approximate size of 500 µm.

Hyperthermic potentiation of cisplatin by magnetic nanoparticle heaters is correlated with an increase in cell membrane fluidity.

Magnetic fluid hyperthermia as a cancer treatment method is an attractive alternative to other forms of hyperthermia. It is based on the heat released by magnetic nanoparticles subjected to an alternating magnetic field. Recent studies have shown that magnetic fluid hyperthermia-treated cells respond significantly better to chemotherapeutic treatment compared with cells treated with hot water hyperthermia under the same temperature conditions. We hypothesized that this synergistic effect is due to an additional stress on the cellular membrane, independent of the thermal heat dose effect that is induced by nanoparticles exposed to an alternating magnetic field. This would result in an increase in Cis-diammine-dichloroplatinum (II) (cDDP, cisplatin) uptake via passive transport. To test this hypothesis, we exposed cDDP-treated cells to extracellular copper in order to hinder the human cell copper transporter (hCTR1)-mediated active transport of cDDP. This, in turn, can increase the passive transport of the drug through the cell membrane. Our results did not show statistically significant differences in surviving fractions for cells treated concomitantly with magnetic fluid hyperthermia and cDDP, in the presence or absence of copper. Nonetheless, significant copper-dependent variations in cell survival were observed for samples treated with combined cDDP and hot water hyperthermia. These results correlated with platinum uptake studies, which showed that cells treated with magnetic fluid hyperthermia had higher platinum uptake than cells treated with hot water hyperthermia. Changes in membrane fluidity were tested through fluorescence anisotropy measurements using trimethylamine-diphenylhexatriene. Additional uptake studies were conducted with acridine orange and measured by flow cytometry. These studies indicated that magnetic fluid hyperthermia significantly increases cell membrane fluidity relative to hot water hyperthermia and untreated cells, and hence this could be a factor contributing to the increase of cDDP uptake in magnetic fluid hyperthermia-treated cells. Overall, our data provide convincing evidence that cell membrane permeability induced by magnetic fluid hyperthermia is significantly greater than that induced by hot water hyperthermia under similar temperature conditions, and is at least one of the mechanisms responsible for potentiation of cDDP by magnetic fluid hyperthermia in Caco-2 cells.

Hyperthermia induced by magnetic nanoparticles improves the effectiveness of the anticancer drug cis-diamminedichloroplatinum.

The cytotoxic enhancement of cisplatin by magnetic fluid hyperthermia (MFH) was investigated in human colon adenocarcinoma cells (Caco-2). A nanoparticle platform based on iron oxide functionalized with carboxymethyl dextran was employed to produce heat at the nanoscale. To assess the synergistic effect of hyperthermia and the anticancer drug cis-Diamminedichloroplatinum, commonly known as cisplatin (CIS), cell viability was measured 24, 48, and 72 hours after three different combined hyperthermia and CIS exposure sequences. These included CIS incubation prior to hyperthermia or magnetic fluid hyperthermia, CIS exposure only during hyperthermia or MFH, and additional CIS incubation following hyperthermia or MFH. Additional incubation of CIS after hyperthermia treatment appears to be more effective than prior CIS incubation for both hyperthermia treatments. Viability data also indicated that MFH combined with CIS is significantly more effective than hot water hyperthermia at the same temperature. A CIS concentration an order of magnitude lower than the calculated IC50 was found to be very effective in reducing cell viability. Such dramatic differences suggest that MFH may enhance the passive transport of CIS.

Titanium(IV) complexes: cytotoxicity and cellular uptake of titanium(IV) complexes on caco-2 cell line.

Replacement of the ancillary ligand in titanocene dichloride by amino acids provides titanocene species with high water solubility. As part of our research efforts in the area of titanium-based antitumor agents, we have investigated the cytotoxic activity of Cp(2)TiCl(2) and three water soluble titanocene-amino acid complexes - [Cp(2)Ti(aa)(2)]Cl(2) (aa=L-cysteine, L-methionine, and D-penicillamine) and one water soluble coordination compound, [Ti(4)(maltolato)(8)(micro-O)(4)] on the human colon adenocarcinoma cell line, Caco-2. At pH of 7.4 all titanocene species decompose extensively while [Ti(4)(maltolato)(8)(micro-O)(4)] is stable for over seven days. In terms of cytotoxicity, the [Cp(2)Ti(aa)(2)]Cl(2) and [Ti(4)(maltolato)(8)(micro-O)(4)] complexes exhibited slightly higher toxicity than titanocene dichloride at 24h, but at 72h titanocene dichloride and [Ti(4)(maltolato)(8)(micro-O)(4)] have higher cytotoxic activity. Cellular titanium uptake was quantified at various time intervals to investigate the possible relationship between Ti uptake and cellular toxicity. Results indicated that there was not a clear relationship between Ti uptake and cytotoxicity. A structure-activity relationship is discussed.

Poly(Ethylene Glycol) hydrogels as possible multidrug resistance associated protein (MRP) inhibitors.

Multidrug resistance (MDR) has been recognized by the scientific community as one of the major hurdles in the bioavailability of broad spectrum of drugs. This work focuses on the examination of the effects of the variables involved in hydrogel design on the multidrug resistance phenomenon. Hydrogels were synthesized using monomer lengths of 200, 400 and 1000 g/mol and a crosslinker length of 1000 and 600 g/mol. Hydrogels were characterized by the determination of release of model substrate Fluorescein sodium salt (FLUO), a multidrug resistance-associated protein (MRP) substrate, from the networks, and its transport trough Caco-2 cells. The effect of the hydrogels on the cytotoxicity of the chemotherapeutic agent 5-Fluoracil, an MRP substrate, was also assessed. The release profile of the model substrate FLUO indicated an anomalous release for all the morphologies with both Fickian and relaxation effects playing a role in the release of the substrate, making these hydrogels excellent candidates for controlled drug delivery applications. Preliminary results on the fluorescein sodium salt transport across Caco-2 cell monolayer in contact with 10 mg/mL PEG hydrogels suspensions showed a transport enhancement of up to 152%. Finally, cytotoxicity of Caco-2 cells with chemotherapeutic agent 5-Fluoracil was enhanced in the presence of the hydrogels. This data suggests that PEG hydrogels are acting as MRP inhibitors.