Responsive Calcium (Ca²⁺) Alginate-Chitosan Based Hydrogel: A Promising Biomaterial for Spinal Cord Injury

Spinal cord injury is damage to the spinal cord which causes lesions in the spinal cord and leads to an increase in extracellular Ca2+. It results in additional neuronal loss which causes temporary/permanent disability or even death. The aim of this study was to determine characteristics and the best composition of alginate – chitosan hydrogel responsive to Calcium (Ca2+) for spinal cord injury. Hydrogel synthesis with its compositions, namely chitosan was dissolved in 0.4% acetic acid, neutralized in pH 7 with 0.5 M NaOH, added some 0.85% NaCl in it, and added 5 alginate variations which were dissolved in 0.85% NaCl, next will centrifugation method. Based on the FTIR test, hydrogel showed stretching vibrations of Chitosan’s O–H bonds appeared in 3415.93cm-1 wavenumber, while Na groups of alginate isomer appeared in 1413.82 cm-1 wavenumber. The results of the cytotoxicity test using the MTT Assay method showed live cell percentage from less than 50% to 52.61% in Sample B and 83.83% in Sample C. The results of the injectability test showed that all samples were injectable with the highest percentage of injectability at 98.283%. The results of the UV-Vis spectrophotometric test showed that all hydrogel samples were able to absorb Ca2+. Hydrogels can be degraded at more than 90% within 14 days. The results of the morphology test (SEM) obtained 84.7-99.6 μm pore sizes.

Bioelectronics of The Cellular Cytoskeleton: Monitoring Cytoskeletal Conductance Variation for Sensing Drug Resistance

Actin and microtubules form cellular cytoskeletal network, which mediates cell shape, motility and proliferation and are key targets for cancer therapy. Changes in cytoskeletal organization dramatically affect mechanical properties of the cells and correlate with proliferative capacity and invasiveness of cancer cells. Changes in the cytoskeletal network expectedly lead to altered nonmechanical material properties including electrical conductivity as well. Here we applied, for the first time, microtubule and actin based electrical measurement to monitor changes in the electrical properties of breast cancer cells upon administration of anti-tubulin and anti-actin drugs, respectively. Semiconductive behavior of microtubules and conductive behavior of actins presented different bioelectrical responses (in similar frequencies) of the cells treated by anti-tubulin with respect to anti-actin drugs. Doped silicon nanowires were applied as the electrodes due to their enhanced interactive surface and compatibility with electronic fabrication process. We found that treatment with Mebendazole (MBZ), a microtubule destabilizing agent, decreases electrical resistance while treatment with Paclitaxel (PTX), a microtubule stabilizing agent, leads to an increase in electrical resistance. In contrast, actin destabilizing agents, Cytochalasin D (CytD), and actin stabilizing agent, Phalloidin, lead to an increased and decreased electrical resistance, respectively. Our study thus provides proof-of-principle of the usage of determining the electrical function of cytoskeletal compartments in grading of cancer as well as drug resistance assays.

Trace Elements and Chemotherapy Sensitivity

Trace elements might be associated with the development of hepatocellular carcinoma (HCC) and the efficacy of chemotherapy against HCC. Therefore, this study aimed to explore the association between trace elements and efficacy of chemotherapy in patients with HCC. Cancer, cancer-adjacent, and cancer-free tissues were collected intraoperatively from 55 patients with HCC between January 2001 and April 2004 at the Affiliated Tumor Hospital of Guangxi Medical University in Guangxi (China), a high HCC incidence area in the world. Trace element levels were analyzed by atomic absorption spectrophotometry. In vitro sensitivity of cancer cells to five chemotherapeutic drugs (5-fluorouracil, doxorubicin, cisplatin, carboplatin, and mitomycin) was tested using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in cancer cells from 32 patients. Zinc, copper, manganese, and selenium levels had the same gradient distribution in different liver tissues: cancer < cancer-adjacent < cancer-free tissues. Copper levels of cancer tissues were negatively correlated with body weight (r = -0.278, P = 0.027), while manganese and selenium levels were negatively correlated with age (r = -0.297, P = 0.015; r = -0.285, P = 0.018, respectively). Simple correlation analyses revealed that the carboplatin sensitivity was negatively correlated with selenium levels of cancer tissues, while doxorubicin sensitivity was negatively correlated with manganese levels (r = -0.497, P = 0.004). Partial correlation analyses showed that doxorubicin sensitivity only was negatively correlated with manganese levels (r = -0.450, P = 0.014). These results suggest that the selenium and manganese content in primary HCC tissues could influence the response of the HCC cells to carboplatin and doxorubicin. These preliminary results provide a basis for future studies.