Irreversible thermal inactivation and conformational lock of alpha glucosidase.

In the present work, we studied the structure-activity relationship and kinetics of thermal inactivation of α-glucosidase A (AglA) in a 50 mM potassium phosphate buffer at pH 6.8 using p-nitrophenyl α-d-glucopyranoside (pNPG) as the synthetic substrate following absorbance at 410 nm by UV-Vis spectrophotometer. The interface structure and residual activity plot were analyzed via biochemical measurements by means of conformational lock theory, as well. The thermal inactivation curves were plotted in temperature interval from 30 to 50 °C. Based on experimental and structural data we suggested intermediates during inactivation before the loss of enzyme activity. Arrhenius plot for thermal inactivation rate constant showed biphasic appearance related to before and after 45°C temperature. The contact areas between two subunits were ruptured and unlocked stepwise during dimer dissociation. Cleavage of these areas induced the dissociation of the subunits along with destruction of the active centers and subsequently the loss of activity. It seems that the contact areas interact with active centers by conformational changes involving secondary structural elements.

Cell-Penetrating Peptides: As a Promising Theranostics Strategy to Circumvent the Blood-Brain Barrier for CNS Diseases.

The passage of therapeutic molecules across the Blood-Brain Barrier (BBB) is a profound challenge for the management of the Central Nervous System (CNS)-related diseases. The ineffectual nature of traditional treatments for CNS disorders led to the abundant endeavor of researchers for the design the effective approaches in order to bypass BBB during recent decades. Cell-Penetrating Peptides (CPPs) were found to be one of the promising strategies to manage CNS disorders. CPPs are short peptide sequences with translocation capacity across the biomembrane. With special regard to their two key advantages like superior permeability as well as low cytotoxicity, these peptide sequences represent an appropriate solution to promote therapeutic/theranostic delivery into the CNS. This scenario highlights CPPs with specific emphasis on their applicability as a novel theranostic delivery system into the brain.

Mesoporous silica nanoparticles for therapeutic/diagnostic applications.

Based on unique intrinsic properties of mesoporous silica nanoparticles (MSNs) such as high surface area, large pore size, good biocompatibility and biodegradability, stable aqueous dispersion, they have received much attention in the recent decades for their applications as a promising platform in the biomedicine field. These porous structures possess a pore size ranging from 2 to 50 nm which make them excellent candidates for various biomedical applications. Herein, at first we described the common approaches of cargo loading and release processes from MSNs. Then, the intracellular uptake, safety and cytotoxicity aspects of MSNs are discussed as well. This review also highlights the most recent advances in the biomedical applications of MSNs, including 1) MSNs-based carriers, 2) MSNs as bioimaging agents, 3) MSNs-based biosensors, 4) MSNs as therapeutic agents (photodynamic therapy), 5) MSN based quantum dots, 6) MSNs as platforms for upconverting nanoparticles, and 6) MSNs in tissue engineering.

SN38 conjugated hyaluronic acid gold nanoparticles as a novel system against metastatic colon cancer cells.

Combination of chemotherapy and photothermal therapy has been proposed for better treatment of metastatic colon cancer. In this study SN38, a highly potent cytotoxic agent, was conjugated to negatively charged hyaluronic acid (HA), which was deposited on the surface of the positively charged gold nanoparticles via electrostatic interaction. The drug conjugation and its interaction with gold nanoparticles were verified by 1H NMR and UV-vis spectroscopies, respectively. The prepared SN38-HA gold NPs are negatively charged spherical nanoparticles with an average size of 75±10nm. In vitro release study revealed that drug release in acidic conditions (pH 5.2) was faster than that in physiological pH. Red light emitting diode (LED, 630nm, 30mW) was used as a light source for photothermal experiments. The drug release in acidic conditions was increased up to 30% using red LED illumination (6min) in comparison with experiment carried out indark. The cytotoxicity study on MUC1 positive HT29, SW480 colon cancer cells and MUC1 negative CHO cells, showed higher toxicity of the nanoparticles on HT29 and SW480 cell lines compared to CHO cells. Confocal microscopy images along with flow cytometry analysis confirm the cytotoxicity results. The incubation time for reaching IC50 decreases from 48h to 24h by LED illumination after nanoparticle treatment. Migratory potential of the HT29 and SW480 cell lines was reduced by co-application of SN38-HA gold NPs and LED radiation. Also anti-proliferative study indicates that LED radiation has increased the cytotoxicity of the nanoparticles and this effect is remained up to 8days.

Targeted Delivery of Cabazitaxel by Conjugation to Albumin-PEG-folate Nanoparticles Using a Cysteine-acrylate Linker and Simple Synthesis Conditions.

BACKGROUND: Cabazitaxel (CBZ) is a new taxane approved by FDA for treatment of castration- resistant prostate cancer not responding to docetaxel. However, CBZ is not a suitable substrate for p-glycoprotein 60, an efflux pump which transports anticancer drugs out of malignant cells and is therefore a promising drug for treatment of multidrug resistant tumors. Similar to other taxanes, the presence of Tween 80 in the CBZ formulation shows that it is insoluble in water. METHODS: In order to increase the solubility and circulation time of this drug, CBZ-human serum albumin (HSA) conjugate was synthesized. The designed linker was composed of methacrylic acid and N-acetyl cysteine to increase the solubility of CBZ and to increase the efficiency of conjugation. Targeting was performed by poly(ethylene glycol)-folic acid amide bound formation with carboxyl groups of HSA during in the step of nanoparticle formation. Cytotoxicity of nanoparticles was evaluated in vitro on HT-29, as a folate negative cell line, and MDA-MB-231, as a folate positive cell line. RESULTS: H-NMR, Gel Permeation Chromatography, High Pressure Liquid Chromatography and UV spectrophotometry analysis confirmed the composition of conjugates. The resulting nanoparticles had a spherical shape, narrow size distribution and mean diameter of 138 nm. The efficiency of conjugation was 41.6 %. The IC50 of CBZ in targeted nanoparticles was 10.1 and 17.4% lower than that of the free CBZ for HT-29 and MDA-MB-231 cells, respectively. CONCLUSION: This designed drug delivery system was more water-soluble and had enhanced in vitro characteristics and higher cytotoxic activity on cancer cells.

Specific targeting delivery to MUC1 overexpressing tumors by albumin-chitosan nanoparticles conjugated to DNA aptamer.

Chitosan-coated human serum albumin nanoparticles were functionalized by MUC1 aptamer to obtain a selective drug carrier toward cancers overexpressing MUC1. The negative charges of albumin nanoparticles were shifted to positive charges by surface modification with chitosan, and MUC1 was conjugated through an acrylate spacer. The cytotoxicity of targeted nanoparticles was significantly more than non-aptamer nanoparticles, and also the chitosan-coated nanoparticles had more cytotoxic effects than the negatively charged albumin nanoparticles. The IC50 of targeted nanoparticles was 28 and 26% of free paclitaxel in MCF7 and T47D cells at 48h, respectively. Confocal laser scanning electron microscopy showed that aptamer conjugation and positive charge increase the cellular uptake. 66% of paclitaxel was released within 32h, but 100% of drug was released at pH=5.5 (similar cancer cells). The paclitaxel plasma amount was at a good level of 17.6% at 2h for increasing the chance of cellular uptake.

Theranostic MUC-1 aptamer targeted gold coated superparamagnetic iron oxide nanoparticles for magnetic resonance imaging and photothermal therapy of colon cancer.

Favorable physiochemical properties and the capability to accommodate targeting moieties make superparamegnetic iron oxide nanoparticles (SPIONs) popular theranostic agents. In this study, we engineered SPIONs for magnetic resonance imaging (MRI) and photothermal therapy of colon cancer cells. SPIONs were synthesized by microemulsion method and were then coated with gold to reduce their cytotoxicity and to confer photothermal capabilities. Subsequently, the NPs were conjugated with thiol modified MUC-1 aptamers. The resulting NPs were spherical, monodisperse and about 19nm in size, as shown by differential light scattering (DLS) and transmission electron microscopy (TEM). UV and X-ray photoelectron spectroscopy (XPS) confirmed the successful gold coating. MTT results showed that Au@SPIONs have insignificant cytotoxicity at the concentration range of 10-100µg/ml (P>0.05) and that NPs covered with protein corona exerted lower cytotoxicity than bare NPs. Furthermore, confocal microscopy confirmed the higher uptake of aptamer-Au@SPIONs in comparison with non-targeted SPIONs. MR imaging revealed that SPIONs produced significant contrast enhancement in vitro and they could be exploited as contrast agents. Finally, cells treated with aptamer-Au@SPIONs exhibited a higher death rate compared to control cells upon exposure to near infrared light (NIR). In conclusion, MUC1-aptamer targeted Au@SPIONs could serve as promising theranostic agents for simultaneous MR imaging and photothermal therapy of cancer cells.

Molecular mechanisms of curcumins suppressing effects on tumorigenesis, angiogenesis and metastasis, focusing on NF-κB pathway.

NF-κB pathway has long been considered as one of the potent prototypical pro-inflammatory signaling pathway and its role in several aspects of human health has been established. Recent studies have suggested that NF-κB activation is the master key in early development and pathobiology of several Cancers. Curcumin is a polyphenolic phytochemical compound with several stablished anti-inflammatory properties and is known to exert its anti-inflammatory effects mostly by interrupting NF-κB signaling pathway at multiple stages. Here we tried to provide a summary of recent finding, focusing on introducing NF-κB signaling pathways and its potential mechanism involved in development of several types of Cancers.

Protein corona hampers targeting potential of MUC1 aptamer functionalized SN-38 core-shell nanoparticles.

Nanoparticles have been considered to improve delivery and physicochemical characteristics of bioactive agents in recent years. In this study, a core-shell chitosan nanoparticulate system was prepared for the targeted delivery of SN-38. SN-38, an active metabolite of camptothecin, conjugated to hyaluronic acid (HA) was used as the shell of chitosan nanoparticles decorated with MUC1 aptamer. The conjugation was confirmed by UV and (1)H NMR techniques. Targeting efficiency was evaluated by confocal microscopy and flow cytometry. It was shown that MUC1 decoration increased the uptake of nanoparticles by HT29 cells, MUC1 positive cell line, while CHO as MUC1 negative cell line showed no enhanced uptake of decorated nanoparticles. Compared to non-targeted nanoparticles, flow cytometric annexin V/PI analyses showed that the nanoparticles exert cytotoxicity through apoptosis. It was, however, shown that protein corona adsorption at the surface of nanoparticles hampered the cytotoxicity of nanoparticles, as there was no difference between the cytotoxicity of targeted and non-targeted nanoparticles, when treated with bovine serum albumin prior to cytotoxicity study.