Self-Activating Therapeutic Nanoparticle: A Targeted Tumor Therapy Using Reactive Oxygen Species Self-Generation and Switch-on Drug Release

One of the recent advances in nanotechnology within the medical field is the development of a nanoformulation of anticancer drugs or photosensitizers. Cancer cell-specific drug delivery and upregulation of the endogenous level of reactive oxygen species (ROS) are important in precision anticancer treatment. Within our article, we report a new therapeutic nanoformulation of cancer cell targeting using endogenous ROS self-generation without an external initiator and a switch-on drug release (ROS-induced cascade nanoparticle degradation and anticancer drug generation). We found a substantial cellular ROS generation by treating an isothiocyanate-containing chemical and functionalizing it onto the surface of porous silicon nanoparticles (pSiNPs) that are biodegradable and ROS-responsive nanocarriers. Simultaneously, we loaded an ROS-responsive prodrug (JS-11) that could be converted to the original anticancer drug, SN-38, and conducted further surface functionalization with a cancer-targeting peptide, CGKRK. We demonstrated the feasibility as a cancer-targeting and self-activating therapeutic nanoparticle in a pancreatic cancer xenograft mouse model, and it showed a superior therapeutic efficacy through ROS-induced therapy and drug-induced cell death. The work presented is a new concept of a nanotherapeutic and provides a more feasible clinical translational pathway.

Amino-decorated mesoporous silica nanoparticles for controlled sofosbuvir delivery

The present study describes synthesis of amino-decorated mesoporous silica nanoparticles (MSNs) for sustained delivery and enhanced bioavailability of sofosbuvir. Sofosbuvir is active against hepatitis C virus and pharmaceutically classified as class III drug according to biopharmaceutics classification system (BCS). MSNs were synthesized using modified sol-gel method and the surface was decorated with amino functionalization. Drug loaded MSNs were also grafted with polyvinyl alcohol in order to compare it with the amino-decorated MSNs for sustained drug release. The prepared MSNs were extensively characterized and the optimized formulation was toxicologically and pharmacokinetically evaluated. The functionalized MSNs of 196 nm size entrapped 29.13% sofosbuvir in the pores, which was also confirmed by the decrease in surface area, pore volume and pore size. The drug-loaded amino-decorated MSNs revealed an improved thermal stability as confirmed by thermal analysis. Amino-decorated MSNs exhibited Fickian diffusion controlled sofosbuvir release as compared with non-functionalized and PVA grafted MSNs. Amino-decorated MSNs were deemed safe to use in Sprague-Dawley rats after 14-days exposure as confirmed by the toxicological studies. More interestingly, we achieved a 2-fold higher bioavailability of sofosbuvir in Sprague-Dawley rats in comparison with sofosbuvir alone, and the T_max was delayed 3-times indicating a sustained release of sofosbuvir.

A Novel, Nonpeptidic, Orally Active Bivalent Inhibitor of Human β-Tryptase

β-Tryptase is released from mast cells upon degranulation in response to allergic and inflammatory stimuli. Human tryptase is a homotetrameric serine protease with 4 identical active sites directed toward a central pore. These active sites present an optimized scenario for the rational design of bivalent inhibitors, which bridge 2 adjacent active sites. Using (3-[1-acylpiperidin-4-yl]phenyl)methanamine as the pharmacophoric core and a disiloxane linker to span 2 active sites we have successfully produced a novel bivalent tryptase inhibitor, compound 1a, with a comparable profile to previously described inhibitors. Pharmacological properties of compound 1a were studied in a range of in vitro enzymic and cellular screening assays, and in vivo xenograft models. This non-peptide inhibitor of tryptase demonstrated superior activity (IC50 at 100 pmol/L tryptase = 1.82 nmol/L) compared to monomeric modes of inhibition. X-ray crystallography validated the dimeric mechanism of inhibition, and 1a demonstrated good oral bioavailability and efficacy in HMC-1 xenograft models. Furthermore, compound 1a demonstrated extremely slow off rates and high selectivity against-related proteases. This highly potent, orally bioavailable and selective inhibitor of human tryptase will be an invaluable tool in future studies to explore the therapeutic potential of attenuating the activity of this elusive target.

Fluoride Varnishes--Is There a Correlation Between Fluoride Release and Deposition on Enamel?

PURPOSE

Fluoride uptake of enamel after application of fluoride varnishes was compared with fluoride release into artificial saliva. The hypothesis was that fluoride uptake is higher for products exhibiting faster fluoride release.

MATERIALS AND METHODS

Fluoride varnishes, i.e. Fluor Protector S, Duraphat, MI Varnish, Clinpro White Varnish, Profluorid Varnish and Enamel Pro Varnish were applied on bovine enamel specimens. Subsequently, specimens were incubated in artificial saliva. After removal of the varnishes, surface bound fluoride was extracted with potassium hydroxide and measured with an ion-selective electrode. Structurally bound fluoride was etched from the same specimens with perchloric acid. Fluoride release of varnish films into artificial saliva was measured for comparison.

RESULTS

After 4 h in artificial saliva, the highest total enamel fluoride uptake of 47.9 μg F·cm-² was found with Fluor Protector S, followed by Enamel Pro Varnish with 22.1 μg F·cm-². The other products ranged between 12-16 μg F·cm-². This was several times higher than the negative control. Fluoride uptake did not correlate with release into artificial saliva. During the first 4 h, Duraphat released the lowest and MI Varnish the highest amount of fluoride with 7.7 and 249 μg F·cm-², respectively. The fluoride uptake of these two products was not statistically different.

CONCLUSION

Enamel fluoride uptake cannot be predicted from the fluoride release rate of a product. Hence, based on the results of this study, fluoride release into artificial saliva is no measure for the efficacy of a fluoride varnish.

Accumulation of magnetic iron oxide nanoparticles coated with variably sized polyethylene glycol in murine tumors

Iron oxide nanoparticles have found widespread applications in different areas including cell separation, drug delivery and as contrast agents. Due to water insolubility and stability issues, nanoparticles utilized for biological applications require coatings such as the commonly employed polyethylene glycol (PEG). Despite its frequent use, the influence of PEG coatings on the physicochemical and biological properties of iron nanoparticles has hitherto not been studied in detail. To address this, we studied the effect of 333-20,000 Da PEG coatings that resulted in larger hydrodynamic size, lower surface charge, longer circulation half-life, and lower uptake in macrophage cells when the particles were coated with high molecular weight (M(w)) PEG molecules. By use of magnetic resonance imaging, we show coating-dependent in vivo uptake in murine tumors with an optimal coating M(w) of 10,000 Da.

Characterization of Drug Release and Diffusion Mechanism Through Hydroxyethylmethacrylate/Methacrylic Acid pH-Sensitive Hydrogel

Hydroxyethylmethacrylate/methacrylic acid copolymer cross-linked with ethylenglycol dimethacrylate was prepared by a bulk free radical polymerization method. The permeability studies of this pH-sensitive hydrogel to drugs with different water solubilities showed a water-content dependent diffusion or pore mechanism for ephedrine HCl (water-soluble model drug), whereas, a partition or solute-diffusion mechanism for indomethacin (a water-insoluble drug) was seen. Data analysis of release tests, according to the swelling interface number and Peppas equation for ephedrine HCl in pH 7.4, showed a biexponential model kinetic, whereas in pH 1.2 a swelling-controlled mechanism was seen. Indomethacin was released by an anomalous or non-Fickian release kinetics.

Study on the endocytosis and the internalization mechanism of aminosilane-coated Fe3O4 nanoparticles in vitro

In this study, the endocytosis and the internalization mechanism of aminosilane-coated Fe(3)O(4) nanoparticles into human lung cancer cell line SPC-A1 was studied compared with human lung cell line WI-38 in vitro. The particle endocytosis behavior was studied by using Transmission Electron Microscope (TEM) and Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). It was found that aminosilane-coated Fe(3)O(4) nanoparticles could be greatly taken up by SPC-A1 human cancer cells (202 pg iron/cell) but not by WI-38 human lung cells (13 pg iron/cell). The particles could be retained in SPC-A1 cells over a number of generations in vitro. Different endocytosis was observed by TEM after SPC-A1 cells were treated with different temperature or with/without Cytochalasin B (Inhibitor of phagocytosis) at 37 degrees C. No nanoparticles were taken up by SPC-A1 after the endocytosis inhibited in low temperature. Restoring the endocytosis activity at 37 degrees C, the process of nanoparticles from coated pit to endosomes and lysosomes was observed by TEM. Endocytosis activity was effectively inhibited by the presence of Cytochalasin B at 37 degrees C, while a lot of nanoparticles were uptaken to the cytoplasm of SPC-A1 cells in the control group. Our results suggest that the process of endocytosis of aminosilane-coated Fe(3)O(4) nanoparticles can efficiently takes place in lung cancer cells and nanoparticles can be kept in cancer cells for generations. Phagocytosis may be involved in the internalization process of aminosilane-coated Fe(3)O(4) nanoparticles.

Specific targeting of tumor angiogenesis by RGD-conjugated ultrasmall superparamagnetic iron oxide particles using a clinical 1.5-T magnetic resonance scanner

Angiogenesis is essential for the development of malignant tumors and provides important targets for tumor diagnosis and therapy. To noninvasively assess the angiogenic profile of tumors, novel alpha(v)beta(3) integrin-targeted ultrasmall superparamagnetic iron oxide particles (USPIOs) were designed and their specific uptake by endothelial cells was evaluated in vitro and in vivo. USPIOs were coated with 3-aminopropyltrimethoxysilane (APTMS) and conjugated with Arg-Gly-Asp (RGD) peptides. Accumulation in human umbilical vein endothelial cells (HUVECs) was evaluated using Prussian blue staining, transmission electron microscopy, magnetic resonance (MR) imaging, and inductively coupled plasma mass spectrometry. Uptake of RGD-USPIO by HUVECs was significantly increased when compared with unlabeled USPIO and could be competitively inhibited by addition of unbound RGD. The ability of the RGD-USPIO to noninvasively distinguish tumors with high (HaCaT-ras-A-5RT3) and lower (A431) area fractions of alpha(v)beta(3) integrin-positive vessels was evaluated using a 1.5-T MR scanner. Indeed, after RGD-USPIO injection, there was a more pronounced decrease in T(2) relaxation times in HaCaT-ras-A-5RT3 tumors than in A431 tumors. Furthermore, T(2)*-weighted images clearly identified the heterogeneous arrangement of vessels with alpha(v)beta(3) integrins in HaCaT-ras-A-5RT3 tumors by an irregular signal intensity decrease. In contrast, in A431 tumors with predominantly small and uniformly distributed vessels, the signal intensity decreased more homogeneously. In summary, RGD-coupled, APTMS-coated USPIOs efficiently label alpha(v)beta(3) integrins expressed on endothelial cells. Furthermore, these molecular MR imaging probes are capable of distinguishing tumors differing in the degree of alpha(v)beta(3) integrin expression and in their angiogenesis profile even when using a clinical 1.5-T MR scanner.

Developmental toxic effects of antifungal flusilazole administered by gavage to mice

BACKGROUND

The developmental toxicity of flusilazole was studied in CD-1 mice after oral administration.

METHODS

Pregnant mice were given flusilazole at doses of 0 (corn oil), 10, 20, and 40 mg/kg/day, by gavage, on gestational days (GD) 6-15.

RESULTS

Maternal toxicity, as evidenced by reduction in body weight gain and signs of toxicity, was observed at the middle- and high-dose groups. No significant incidence of resorptions or death was observed in any of dose groups. There was a pronounced reduction in fetal weight, which was significantly lower than control from 20 and 40 mg/kg/day. There was no significant increase in the incidence of fetuses with external or visceral malformations in any of dose groups, but there was a significant increase in the incidence of skeletal malformations was observed at 20 and 40 mg/kg/day.

CONCLUSIONS

The results of this study reported marked maternal toxicity, growth retardation, and skeletal abnormalities in the mid- and high-dose groups. It seems likely that marked maternal toxicity contributed to the observed alterations in fetal growth retardation and skeletal development. The no-observed-effect level in the present study for maternal and developmental toxicity was 10 mg/kg/day.

Dimethylsilane polyamines: cytostatic compounds with potentials as anticancer drugs. II. Uptake and potential cytotoxic mechanisms

Dimethylsilane tetramines are structural analogues of spermine with a (CH3)2 Si-group incorporated into the central carbon chain. They have potential as anticancer drugs. Their cytotoxic effect was considered to rely mainly on their polyamine antagonist property. In order to obtain new ideas about cellular mechanisms, which are potential targets of the dimethylsilane polyamines, the effects of these compounds on some basic cell functions, such as protein and DNA synthesis, and calmodulin antagonism were studied. In addition, their mode of accumulation in cells was investigated. It became evident that the intracellular accumulation of dimethylsilane polyamines is almost exclusively achieved via the polyamine transport system. However, the exchange of a part of the intracellular natural polyamines against dimethylsilane polyamines has only a small effect on polyamine uptake. Binding to the endoplasmic reticulum and inhibition of protein synthesis are presumably important for the cytotoxic action of bis(11-amino-4,8-diazaundecyl)dimethylsilane, a hexamine, but seem of no importance for the tetramines. Calmodulin antagonism, however, is likely to contribute to their cytotoxic effect.

In vitro and in vivo antimicrobial activity of covalently coupled quaternary ammonium silane coatings on silicone rubber

Biomaterial-centered infection is a dreaded complication associated with the use of biomedical implants. In this paper, the antimicrobial activity of silicone rubber with a covalently coupled 3-(trimethoxysilyl)-propyldimethyloctadecylammonium chloride (QAS) coating was studied in vitro and in vivo. Gram-positive Staphylococcus aureus ATCC 12600, Staphylococcus epidermidis HBH, 102, and Gram-negative Esherichia coli O2K2 and Pseudomonas aeruginos AK1 were seeded on silicone rubber with and without QAS-coating, in the absence or presence of adsorbed human plasma proteins. The viability of the adherent bacteria was determined using a live/dead fluorescent stain and a confocal laser scanning microscope. The coating reduced the viability of adherent staphylococci from 90% to 0%), and of Gram-negative bacteria from 90% to 25% while the presencc of adsorbed plasma proteins had little influence. The biomaterials were also subcutaneously implanted in rats for 3 or 7 days, while pre- or postoperatively seeded with S. aureus ATCC 12600. Preoperative seeding resulted in infection of 7 out of 8 silicone rubber implants against 1 out of 8 QAS-coated silicone rubber implants. Postoperative seeding resulted in similar infection incidences on both implant types, but the numbers of adhering bacteria were 70% lower on QAS-coated silicone rubber. In conclusion, QAS-coated silicone rubber shows antimicrobial properties against adhering bacteria, both in vitro and in vivo.

Metabolism of [(14)C]flusilazole in the goat

[Phenyl(U)-(14)C] and [triazole(3)-(14)C]flusilazole ([(bis 4-fluorophenyl)]methyl(1H-1,2,4-triazole-1-ylmethyl)silane; I) were extensively metabolized when fed to lactating goats (Capra hircus). The primary metabolites identified in goat tissues and milk were bis(4-fluorophenyl)(methyl)silanol (II) and 1H-1,2,4-triazole (III). Concentrations of total radiolabeled residues in the milk ranged from 0.09 to 0.74 microg/mL. Concentrations of radiolabeled residues found in tissues when the [(14)C] label was in the phenyl or triazole position, respectively, were 13.5 and 3.54 microg/g (liver), 8.74 and 0.75 microg/g (kidney), 0.41 and 0.52 microg/g (leg muscle), and 4.07 and 0.94 microg/g (back fat). Urine contained an additional major metabolite identified as [bis(4-fluorophenyl)](methyl)silylmethanol (IV) and its glucuronic acid conjugate (V). With either labeled form of flusilazole, the majority of the recovered radiolabel was excreted in urine or feces.

Penetration of varnishes into demineralized root dentine in vitro

In this paper the penetration of three different varnishes employed in caries prevention (Duraphat, Fluor Protector and Cervitec) into demineralized dentine is quantified using confocal laser scanning microscopy. The results show that the varnish penetration into lesions about 85 microns in depth if for Cervitec about 35 microns and considerably less for Duraphat and Fluor Protector. The penetration is into the dentinal tubules and is influenced by dentinal tubule direction. The drying procedure--pretreatment of the dentine--influences the penetration, though sizeably only for Cervitec applications. This paper shows that varnish penetration into the tissue and presumably 'sealing' tubules completely or partly is valuable with respect to root caries prevention and hypersensitivity.

Photodynamic therapy of ocular melanoma with bis silicon 2,3-naphthalocyanine in a rabbit model

PURPOSE

To investigate bis (tri-n-hexylsiloxy) silicon 2,3-naphthalocyanine (SINc; 0.5 mg/kg) for photodynamic therapy of an experimental ocular melanoma in pigmented rabbits.

METHODS

SINc was dissolved in canola oil by heating, emulsified with Tween 80, and administered by ear vein. Pharmacokinetics were studied in frozen tumor sections by fluorescence microscopy using a charge coupled device, camera-based, low-light detection system with digital image processing at 1 and 24 hours. A Ti:sapphire laser and a microlens were used to deliver the light (770 nm; 40 mW/cm2; 20 J/cm2). A control rabbit received light without SINc.

RESULTS

Localization studies of SINc showed intravascular distribution shifting to a tumor stromal and perivascular distribution 24 hours after treatment. Tissue thermal damage after irradiation was minimal in the control. Exudative retinal detachments were not observed. Tumor destruction was observed, with sharp demarcation to a depth of 3.5 mm.

CONCLUSIONS

Tumor light penetration was good at 770 nm, and thermal effects from the exciting light alone were minimal. Photodynamic therapy with SINc resulted in localized tumor destruction reflecting the light beam path without damage to adjacent tissue or intraocular complications.

Distribution and elimination of RGH-5002 in rats

In the present study distribution and elimination of RGH-5002--a new centrally acting muscle relaxant--were investigated in rats by using 14C-labelled compound. Whole-body autoradiography and quantitative determination of the radioactivity in various organs following single and repeated oral administration of [14C]RGH-5002 demonstrated extensive distribution of the drug with high levels in the gastrointestinal tract, kidneys, liver, endocrine and exocrine glands and lungs. Minimal accumulation was observed after repeated (8 days) administration. The same distribution characteristics were observed in both sexes. In pregnant rats radioactivity appeared in the placenta and fetal tissues. Elimination was investigated by measuring radioactivity in 24 h fractions of urine and faeces after single dose administration of the drug. The larger portion of radioactivity was excreted in the urine (81.67 +/- 1.61% of the dose). The faecal recovery was 11.12 +/- 1.19% of the administered dose. Approximately 80% of the excreted radioactivity was recovered within the first 24 hours.

Photodynamic therapy of B16 pigmented melanoma with liposome-delivered Si(IV)-naphthalocyanine

The possibility of extending photodynamic therapy to the treatment of highly pigmented neoplastic lesions was tested by using Si(IV)-naphthalocyanine (SiNc) as a tumor-localizing agent. Si(IV)-naphthalocyanine displays intense absorbance at 776 nm (epsilon = 5 x 10(5) M-1 cm-1), where melanin absorption becomes weaker. As an experimental model we selected B16 pigmented melanoma subcutaneously transplanted to C57BL mice. Upon injection of 0.5 or 1 mg kg-1 of liposome-incorporated SiNc, maximal accumulation of the photosensitizer in the tumor was observed at 24 h with recoveries of 0.35 and 0.57 microgram g-1, respectively. However, the tumor targeting by SiNc shows essentially no selectivity, since the photosensitizer concentrations in the skin (peritumoral tissue) were very similar to those found in the tumor at all postinjection times examined by us. Irradiation of SiNc-loaded melanoma with 776 nm light from a diode laser at 24 h postinjection induces tumor necrosis and delay of tumor growth. The effect appears to be of purely photochemical nature at dose rates up to 260 mW cm-2; at higher dose rates, thermal effects are likely to become important.

Protective effect of topically applied fluoride in relation to fluoride sensitivity of mutans streptococci

The aim of the present in vitro experiments was to determine whether the protection of enamel by topically applied fluoride against demineralization by bacterial acids would depend on the fluoride sensitivity of the bacteria. Glucose-agarose gel suspensions of fluoride-sensitive and fluoride-resistant mutans streptococci were placed on bovine enamel specimens with different amounts of fluoride. One group of specimens was untreated, a second group had been pretreated with a F-lacquer, and a third group had been pretreated with the F-lacquer and rinsed subsequently with a KOH-solution, to remove deposited CaF2. After 22-hour incubations at 37 degrees C, the amounts of calcium and lactate and the pH of the agarose gels were determined. This procedure was repeated on three consecutive days. Two parent S. mutans strains, one parent S. sobrinus strain, and five fluoride-resistant derivatives were tested. Both pretreatments gave a significant protection to the enamel specimens. For the S. mutans strains, the degree of protection did not depend on the fluoride sensitivity of the strains. For the S. sobrinus strains, the results suggested a reduced protection against demineralization by the fluoride-resistant derivatives. Only from the second group of enamel specimens was enough fluoride released for inhibition of bacterial metabolism. Presumably, it was released by the dissolution of CaF2. It is concluded that a possible adaptation of mutans streptococci in dental plaque to frequent exposures to fluoride will not necessarily decrease the caries-preventive effects caused by topically applied fluoride agents.

Fluoride uptake by enamel in vitro following application of various topical fluoride preparations

Two conventional topical fluoride preparations; APF and neutral 2% NaF gel and two fluoride varnishes; Duraphat and Fluor Protector, were applied to 60 permanent and 20 primary teeth. The teeth were halved to provide test and control groups, and the fluoride uptake was measured using a micro acid etch technique, after 30 seconds and 60 seconds etching periods. All topical fluoride preparations in our study caused some fluoride uptake in permanent and primary tooth enamel compared to the control groups. Duraphat and APF were found to be more effective than the other agents.