Differential Surface Engineering Generates Core-Shell Porous Silicon Nanoparticles for Controlled and Targeted Delivery of an Anticancer Drug.

An approach to differentially modify the internal surface of porous silicon nanoparticles (pSiNPs) with hydrophobic dodecene and the external surface with antifouling poly-N-(2-hydroxypropyl) acrylamide (polyHPAm) as well as a cell-targeting peptide was developed. Specifically, to generate these core-shell pSiNPs, the interior surface of a porous silicon (pSi) film was hydrosilylated with 1-dodecene, followed by ultrasonication to create pSiNPs. The new external surfaces were modified by silanization with a polymerization initiator, and surface-initiated atom transfer radical polymerization was performed to introduce polyHPAm brushes. Afterward, a fraction of the polymer side chain hydroxyl groups was activated to conjugate cRGDfK─a peptide with a high affinity and selectivity for the ανß3 integrin receptor that is overexpressed in prostate and melanoma cancers. Finally, camptothecin, a hydrophobic anti-cancer drug, was successfully loaded into the pores. This drug delivery system showed excellent colloidal stability in a cell culture medium, and the in vitro drug release kinetics could be fine-tuned by the combination of internal and external surface modifications. In vitro studies by confocal microscopy and flow cytometry revealed improved cellular association attributed to cRGDfK. Furthermore, the cell viability results showed that the drug-loaded and peptide-functionalized nanoparticles had enhanced cytotoxicity toward a C4-2B prostate carcinoma cell line in both 2D cell culture and a 3D spheroid model.

Activation of multiple proteolysis systems contributes to acute cadmium cytotoxicity.

Cadmium exhibits both toxic and carcinogenic effects, and its cytotoxicity is linked to various cellular pathways, such as oxidative stress, ubiquitin-proteasome, and p53-mediated response pathways. The molecular mechanism(s) underlying cadmium cytotoxicity appears to be complex, but remains largely unclear. Here, we examined the effects of cadmium on the protein catabolism using two surrogate markers, DNA topoisomerases I and II alpha and its contribution to cytotoxicity. We have found that cadmium exposure induced time- and concentration-dependent decreases in the protein level of surrogate markers and therefore suggest that cadmium may be involved in proteolysis system activation. A pharmacological study further revealed the novel role(s) of these proteolytic activities and reactive oxygen species (ROS) in the cadmium-induced acute toxicity: (i) Proteasome inhibition only partially relieved the cadmium-induced proteolysis of topoisomerases; (ii) Moreover, we report for the first time that the activation of metalloproteases, serine proteases, and cysteine proteases contributes to the acute cadmium cytotoxicity; (iii) Consistent with the notion that both ROS generation and proteolysis system activation contribute to the cadmium-induced proteolysis and cytotoxicity, the scavenger N-acetylcysteine and aforementioned protease inhibition not only reduced the cadmium-induced topoisomerase degradation but also alleviated the cadmium-induced cell killing. Taken together, acute cadmium exposure may activate multiple proteolytic systems and ROS formation, subsequently leading to intracellular damage and cytotoxicity. Thus, our results provide a novel insight into potential action mechanism(s) by which cadmium exerts its cytotoxic effect and suggest potential strategies to prevent cadmium-associated acute toxicity.

XPS Analysis of 2- and 3-Aminothiophenol Grafted on Silicon (111) Hydride Surfaces.

Following on from our previous study on the resonance/inductive structures of ethynylaniline, this report examines similar effects arising from resonance structures with aromatic aminothiophenol with dual electron-donating substituents. In brief, 2- and 3-aminothiophenol were thermally grafted on silicon (111) hydride substrate at 130 °C under nonpolar aprotic mesitylene. From the examination of high resolution XPS Si2p, N1s, and S2p spectrum, it was noticed that there was a strong preference of NH2 over SH to form Si⁻N linkage on the silicon hydride surface for 2-aminothiophenol. However, for 3-aminothiophenol, there was a switch in reactivity of the silicon hydride toward SH group. This was attributed to the antagonistic and cooperative resonance effects for 2- and 3-aminothiophenol, respectively. The data strongly suggested that the net resonance of the benzylic-based compound could have played an important role in the net distribution of negative charge along the benzylic framework and subsequently influenced the outcome of the surface reaction. To the best of the authors' knowledge, this correlation between dual electron-donating substituents and the outcome of the nucleophilic addition toward silicon hydride surfaces has not been described before in literature.

Bioactivating Silicon (100) Surfaces with Novel UV Grafting of Cyclopropylamine for Promotion of Cell Adhesion.

In this report, utraviolent (UV) photoionization of cyclopropylamine on silicon (100) hydride was employed to examine interfacing with three different epithelial cell types (MDA-MB 231, AGS and HEC1A). The cellular viability using this novel methodology had been quantified to evaluate the bioactivating potential of this ring-opening chemistry when compared to standardized controls (aminopropyltriethoxylamine, collagen and poly-L lysine). X-ray photospectroscopy (XPS) and atomic force microscopy (AFM) were used to characterize surface chemistry composition, while cell viability and confocal microscopy after 24 h of incubation were performed. Based on the results acquired from this novel ring-opening metastasis process, the promotion of cell adhesion and viability was found to be higher using this chemistry when compared to other conventional control groups, even for the collagen coating, without any observable issues of cytotoxicity.

Anthracenedione-methionine conjugates are novel topoisomerase II-targeting anticancer agents with favorable drug resistance profiles.

Structure-associated drug resistance and DNA-unwinding abilities have greatly limited the clinical usage of anthracenediones, including mitoxantrone (MX) and ametantrone (AT), which intercalate into DNA and induce topoisomerase II (TOP2)-mediated DNA break. We studied a series of 1,4-bis(2-amino-ethylamino) MX- and AT-amino acid conjugates (M/AACs) and showed that abilities in cancer cell killing correlate with the amounts of chromosomal DNA breaks induced by M/AACs. Notably, the 1,4-bis-L/l-methionine-conjugated MAC (L/LMet-MAC) exhibits DNA-breaking, cancer cell-killing and anti-tumor activities rivaling those of MX. Interestingly, l- and d-form Met-M/AACs unwind DNA poorly compared to MX and AT. The roles of the two human TOP2 isozymes (hTOP2α and 2ß) in the L/LMet-MAC-induced DNA breakage and cancer cell-killing were suggested by the following observations: (i) M/AAC-induced DNA breakage, cytotoxicity and apoptosis are greatly reduced in various TOP2-deficient conditions; (ii) DNA breaks induced by MACs are highly reversible and effectively antagonized by the TOP2 catalytic inhibitors; (iii) MACs induced differential TOP2-mediated DNA cleavage in vitro using recombinant hTOP2α proteins and the formation of hTOP2α/ßcc in the cell culture system. Interestingly, d-aa-conjugated MACs often caused a lower level in hTOP2-mediated DNA breaks and cell-killing than the corresponding l-form ones indicating a steric-specific effect of MACs. Together, our results suggest that both enzyme- and DNA-drug interactions might contribute to TOP2-targeting by M/AACs. Furthermore, Met-MACs are poor substrates for the MDR1 transporter. Therefore, L/LMet-MAC represents a promising class of TOP2-targeting drugs with favorable drug resistance profiles.

Chronic hepatitis ameliorates anaemia in haemodialysis patients.

BACKGROUND: Study for influence of chronic hepatitis (CH) on anaemia in haemodialysis (HD) patients remains inconclusive. We aim to characterize the red cell status between CH and hepatitis-free groups among the HD population. METHODS: We retrospectively analysed 80 chronic HD patients from Taipei Medical University Hospital with monthly sampled biochemical study between December 2004 and December 2005. Data classified according to the hepatitis-free, chronic hepatitis B and C groups were expressed as mean +/- standard deviation. Student's t-test and anova were used to determine the mean difference for continuous variables. RESULTS: Age, Kt/V, systolic or diastolic blood pressure, body mass index, total cholesterol and triglyceride were not different between CH and hepatitis-free groups. HD duration (P = 0.0002), aspartate (P < 0.0001), alanine aminotransferase (P < 0.0001), alkaline phosphatase (P = 0.04), haemoglobin (P = 0.0066) and haematocrit (P = 0.002) were significantly more elevated in the CH group demanding less erythropoietin dose than in the hepatitis-free group. CONCLUSION: Our study demonstrated that lessened anaemia was observed in CH, which demanded less erythropoietin dose.

Synthesis, DNA binding, and cytotoxicity of 1,4-bis(2-amino-ethylamino)anthraquinone-amino acid conjugates.

Two series of 1,4-bis(2-amino-ethylamino)anthraquinone-amino acid conjugates (BACs), ametantrone (AT)-amino acid conjugates (AACs) and mitoxantrone (MX)-amino acid conjugates (MACs), were designed and synthesized. The DNA binding of BACs was evaluated by DNA thermal denaturation experiment. In the series, the methionine-substituted BACs had the weakest DNA binding, while the lysine-substituted BACs had the highest T(m) values. The abilities of BACs to inhibit the growth of MCF-7, NCI-H460, SF-268, and PC-3 cell lines were determined. l-Met-MAC 16 and l-Lys-MAC 20 were the most potent growth inhibitors. MAC 16 was more cytotoxic than MX, whereas the T(m) of MAC 16 was much lower than that of MX. In contrast to MAC 16, l-Lys-MAC 20 demonstrated higher T(m) than MX. These data suggested that Met-BACs possessed a different pharmacological profile, in which the ability to stabilize DNA is not parallel to the ability to kill cancer cells, from that of AT and MX. The primary mechanism of cytotoxicity for MAC 16 was most likely through TOP2 poisoning. Therefore, MAC 16 may provide a lead for the development of novel generations of anthraquinone-type antitumor agents.