Selection of DNA aptamers for tramadol through the systematic evolution of ligands by exponential enrichment method for fabrication of a sensitive fluorescent aptasensor based on graphene oxide

Tramadol hydrochloride (TH), as an atypical opioid and a 4-phenyl-piperidine analogue of codeine, is mainly used for treating moderate to severe pains. Due to its extensive application, the consequent need for its analysis in various samples is essential. The current study focuses on the introduction of a rapid fluorescent assay using graphene oxide (GO) and aptamer for determination of tramadol in serum samples. Specific ssDNA aptamers for TH were developed by SELEX (Systematic Evolution of Ligands by EXponential Enrichment) technique using GO as a fluorescence quencher. After 10 rounds, two aptamers (Apt19 and Apt39) were selected from various families. Then, the binding constants of aptamers were measured using fluorometric assay and finally Apt39 (labeled with ATTO 647N) was chosen for development of a fluorescent aptasensor because this aptamer bound to TH with high affinity (K_d = 178.4 nM) and specificity. The current analytical system showed detection limits of 1.04 nM and 2.56 nM in serum sample and phosphate buffer saline (10 mM PBS), respectively.

Protective Effect of Crocin on Malathion-induced Cardiotoxicity in Rats: A Biochemical, Histopathological and Proteomics Study

In this study, the protective effect of crocin on malathion (MTN) induced cardiotoxicity in rats in subacute exposure was evaluated. Rats were divided into 6 groups; control (normal saline); MTN (100 mg/kg); MTN + crocin (10, 20 and 40 mg/kg) and MTN + vitamin E 200 IU/kg. Treatments were continued for two weeks. Creatine phosphokinase MB (CK-MB), malondialdehyde (MDA) and glutathione (GSH) levels were evaluated in heart tissue at the end of treatments. The effect of crocin and MTN on histopathological changes in rat cardiac tissue was also investigated. The alteration of protein profile in the heart of the animals exposed to MTN was evaluated by proteomic approach through two-dimensional gel electrophoresis followed by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) software. MTN induced histopathological damages and elevated the level of cardiac marker CK-MB (P < 0.01). The level of MDA increased and the level of GSH reduced (P < 0.001). MDA levels were reduced in all crocin plus MTN groups (P < 0.001) and vitamin E plus MTN (P < 0.001) groups as compared to MTN groups. However, in the crocin (10 mg/kg) + MTN group, the content of GSH compared to MTN treated rats increased (P < 0.001). Protein abundance analysis identified proteins implicated in cardiac necrosis, tricarboxylic acid cycle, cellular energy homeostasis, arrhythmias, heart development, heart failure and cardiovascular homeostasis to be affected by MTN. In summary, MTN may induce damage in the heart tissue of rats following subacute exposure and crocin, as an antioxidant, showed protective effects against MTN cardiotoxicity.

Application of the catalytic activity of gold nanoparticles for development of optical aptasensors

Biosensor technology is considered to be a great alternative in analytical techniques over the conventional methods. Among many recently developed techniques and devices, aptasensors are interesting because of their high specificity, selectivity and sensitivity. Combining aptamer as a biological recognition element with gold nanoparticles (AuNPs) as probe, are becoming more general owing to their beneficial properties, including low cost and ability to analyze specific targets on-site and using naked eye. Hydrogen bonds, nucleic acid hybridization, aptamer-target and antigen-antibody binding, Raman signature, enzyme inhibition, and enzyme-mimicking activity are main different sensing strategies exploited in AuNPs-based optical aptasensors. In this review article, we discussed the recent advances in optical aptasensors with a special emphasis on the catalytic activity property of AuNPs.

A novel colorimetric aptasensor for ultrasensitive detection of aflatoxin M1 based on the combination of CRISPR-Cas12a, rolling circle amplification and catalytic activity of gold nanoparticles

Colorimetric approaches have received noticeable attention among sensing methods in view of simplicity and watching the color change of sample by the naked eyes. However, developing colorimetric sensing methods which show high sensitivity is still problematic. Herein, based on CRISPR-Cas12a, rolling circle amplification (RCA) and catalytic activity of gold nanoparticles (AuNPs), a colorimetric aptasensor was introduced for highly sensitive detection of aflatoxin M₁ (AFM₁). In the presence of AFM₁, the CRISPR-Cas12a is inactivated and large single-stranded DNA (ssDNA) structures are formed on the surface of AuNPs following the addition of T4 DNA ligase and phi29 DNA polymerase. So, the sample color remains yellow after addition of 4-nitrophenol. However, no huge DNA structure is observed on the surface of AuNPs in the absence of target because of activation of CRISPR-Cas12a and digestion of primer. So, the color of sample switches to colorless. The results indicated that the biosensor had high selectivity toward AFM₁ and the approach achieved a detection limit as low as 0.05 ng/L. In addition, it could sensitively identify AFM₁ in the spiked milk samples. Overall, this approach is highly sensitive and does not require sophisticated equipment. Therefore, it maintains promising potential for other mycotoxins detection in real samples by simply replacing the applied sequences.

Targeted SPION siderophore conjugate loaded with doxorubicin as a theranostic agent for imaging and treatment of colon carcinoma

Recently, the siderophores have opened new horizons in nanomedicine. The current study aimed to design a theranostic platform based on superparamagnetic iron oxide nanoparticles-pyoverdine (SPION/PVD) conjugates bound to MUC1 aptamer (MUC1_Apt) and loaded with doxorubicin (DOX) as an anti-cancer agent. The SPION/PVD complex was covalently conjugated to MUC1_Apt and loaded with DOX to prepare a targeted drug delivery system (SPION/PVD/MUC1_Apt/DOX). The investigation of cellular cytotoxicity and uptake of formulations by MTT and flow cytometry in both MUC1 positive (C26) and MUC1 negative (CHO) cell lines revealed that MUC1_Apt could improve both cellular uptake and toxicity in the C26 cell line. The evaluation of tumor-targeting activity by in vivo bio-distribution showed that the targeted formulation could enhance tumor inhibitory growth effect and survival rate in C26 tumor-bearing mice. Furthermore, the potential of synthesized SPION/PVD/MUC1_Apt/DOX complex as diagnostic agents was investigated by magnetic resonance imaging (MRI) which improved the contrast of tumor site in MRI. Our findings confirm that aptamer-targeted PVD chelated the SPION as a diagnostic agent and loaded with DOX as a chemotherapeutic drug, would be beneficial as a novel theranostic platform.

A novel liquid crystal-based aptasensor for ultra-low detection of ochratoxin a using a π-shaped DNA structure: Promising for future on-site detection test strips

Ochratoxin A (OTA) as the most dangerous mycotoxin is produced by Aspergillus Ochraceus and Penicillium verrucosum. OTA can be found in beverages and foodstuffs that induces the teratogenic, nephrotoxic, carcinogenic, and immunosuppressive effects on humans. Hence, developing highly sensitive methods for its detection is of great importance. Herein, a novel aptasensor was designed for the label-free monitoring of the ultra-low OTA levels by a combination of the superiority of aptamers and long-range orientational order of liquid crystals (LCs). The aptasensing strategy was based on the conformational switch of the immobilized π-shaped DNA structure on the glass substrate in presence of the target. A shift in the orientation of LCs from random to homeotropic state led to the apparent alteration of the optical appearance of the aptasensor platform from bright to dark. The LC-based aptasensor especially detects OTA at the ultra-trace level as low as 0.63 aM with comparable selectivity. The aptasensor could detect OTA successfully in the grape juice, coffee, and human serum samples. The LC-based aptasensor paves a way for developing portable and real-time sensing probes with high performance for food safety control and clinical application.

Fabrication of versatile targeted lipopolymersomes for improved camptothecin efficacy against colon adenocarcinoma in vitro and in vivo

BACKGROUND

Hybrid vesicular systems (lipopolymersomes) are promising platforms for minimizing the liposomes and polymersomes disadvantages in terms of chemotherapeutic transportation. In this regard, lipopolymersome has been designed to integrate the advantage of both polymersomes and liposomes to enable better structural integrity of the bilayer after encapsulation of hydrophobic drugs while maintaining the soft nature of liposomes, superior serum stability, and high encapsulation efficiency of cargos in the bilayer segment.

RESEARCH DESIGN AND METHODS

In the present study, we reported preparation and characterization of five camptothecin (CPT)-loaded lipopolymersomal formulations composed of poly (ethylene glycol)-poly (lactic acid) (PEG-PLA) and dipalmitoylphosphatidylcholine (DPPC) at different molar ratios using film rehydration method. Afterward, the preferred formulation was tagged with AS1411 DNA aptamer in order to evaluate the therapeutic index using nucleolin-positive colon cancer cell lines (HT29 and C26).

RESULTS

The obtained data indicated that the prepared CPT-loaded lipopolymersome at a PEG-PLA: DPPC ratio of 75:25 exhibited superior stability and high loading capacity compared to other systems. Moreover, high cytotoxicity of the aptamer-targeted lipopolymersome and increased tumor accumulation were observed in comparison with non-targeted one.

CONCLUSIONS

The designed polymer-rich lipopolymersomal platform offers bright future for the development of potent nanomedicine against cancer.

Targeted delivery and controlled release of doxorubicin to cancer cells by smart ATP-responsive Y-shaped DNA structure-capped mesoporous silica nanoparticles

In this study, a dual-receptor doxorubicin-targeted delivery system based on mesoporous silica nanoparticles (MSNs) modified with mucine-1 and ATP aptamers (DOX@MSNs-Apts) was developed. An amine-modified mucine-1 (MUC1) aptamer was covalently anchored on the surface of carboxyl-functionalized MSNs. Then, ATP aptamers (ATP1 and ATP2 aptamers) were immobilized on the surface of MSNs through partial hybridization with the MUC1 aptamer by forming a Y-shaped DNA structure on the MSNs surface (DOX@MSNs-Apts) as a gatekeeper. The developed DOX@MSNs-Apts exhibited high DOX loading capacity. In addition, it indicated an ATP-responsive feature, leading to the release of DOX in the environment with high ATP concentration (10 mM), similar to the intracellular environment of tumor cells. This property demonstrated that anticancer drug (DOX) could be entrapped inside the nanocarrier with nearly no leakage in blood and a very low concentration of ATP (1 μM). It was found that after the internalization of DOX@MSNs-MUC1 by cancer cells via the MUC1 receptor-mediated endocytosis, the ATP aptamers left the surface of the nanocarrier, allowing for rapid DOX release. DOX@MSNs-Apts indicated higher cellular uptake in MCF-7 and C26 cancer cells (MUC1+), rather than CHO cells (MUC1-). The in vitro cytotoxicity and the in vivo antitumor efficacy of DOX@MSNs-Apts showed greater cytotoxicity than the nanoparticles decorated with scrambled ATP aptamers (DOX@MSNs-Apts scrambled) in C26 and MCF-7 cell lines (MUC1+). The biodistribution and in vivo anticancer efficacy on the C26 tumor bearing mice indicated that the DOX@MSNs-Apts had a higher tumor accumulation and superior tumor growth inhibitory effect compared to free DOX and their scrambled aptamers, DOX@MSNs-Apts scrambled. Overall, the obtained results indicated that the prepared smart platform could reveal new insights into the treatment of cancer.

Aptamer-based ATP-responsive delivery systems for cancer diagnosis and treatment

In recent years, many stimuli-triggered drug delivery platforms have been designed to deliver drugs accurately to specific sites and reduce their side effects, improving "on-demand" therapeutic efficacy. Adenosine-5'-triphosphate (ATP)-responsive drug delivery methods are examples of these systems that use ATP molecules as a trigger for delivery of therapeutic agents. Since intra- and extra-cellular ATP concentrations are significantly different from each other (1-10 mM and <0.4 mM, respectively), the use of ATP can be a practical method for regulating drug release. Aptamers possess unique properties including, ligand-specific response, short sequence (~ 20-80 bases) and easy functionalization. Thus, their combination with ATP-responsive systems results in more accurate drug delivery systems and greater control of drug release. A wide range of nanoparticles, such as polymeric nanogels, liposomes, metallic nanoparticles, protein, or DNA nano-assemblies, have been employed in the fabrication of nanocarriers. In this review, we describe several ATP-responsive drug delivery systems based on the various carriers and discuss the challenges and strengths of each method.

Fabrication of anionic dextran-coated micelles for aptamer targeted delivery of camptothecin and survivin-shRNA to colon adenocarcinoma

In this study, we synthesized PLA-PEI micelles which was co-loaded with an anticancer drug, camptothecin (CPT), and survivin-shRNA (sur-shRNA). The hydrophobic CPT was encapsulated in the core of the polymeric micelles while sur-shRNA was adsorbed on the shell of the cationic micelles. Then, the positively-charged sur-shRNA-loaded micelles were coated with poly carboxylic acid dextran (PCAD) to form PLA/PEI-CPT-SUR-DEX. To selectively target the system to colon cancer cells, AS1411 aptamer was covalently attached to the surface of the PCAD-coated nanoparticles (PLA/PEI-CPT-SUR-DEX-APT). PLA/PEI-CPT-SUR-DEX-APT enhanced cellular uptake through receptor-mediated endocytosis followed by increased CPT accumulation, downregulation of survivin, and thereby 38% cell apoptosis. In C26 tumor-bearing mice models, after administered intravenously, PLA/PEI-CPT-SUR-DEX-APT and PLA/PEI-CPT-SUR-DEX formulations resulted in a significant inhibition of the tumor growth with tumor inhibition rate of 93% and 87%, respectively. Therefore, PLA/PEI-CPT-SUR-DEX-APT could be a versatile co-delivery vehicle for promising therapy of colorectal cancer.

Identification and Immunological Characterization of Somatic Proteins from Adults of Toxocara cati by Proteomics Technique

Background:

Toxocara cati is considered as one of the main etiological agents of toxocariasis with global and regional importance. As there is no information on proteomics of T. cati, herein, we reported the results obtained by proteomic analysis of somatic proteins extract, using a mass spectrometry (LC–MS/MS) approach.

Methods:

Somatic extract fractions were separated by two-dimensional SDS-PAGE and were electro blotted on to PVDF membranes for immunoblot analysis, then collected the immunogenic spots which response of antibodies of the paratenic hosts (mice) to the antigens (Mashhad, 2017), and analyzed by LC–MS/MS. The LC-MS/MS data were analyzed by Mascot database, Taxonomy Toxocara, and common contaminants, in Omics Center, Biotechnology Medical University of Graz (Austria, 2018).

Result:

The protein spots were isolated between 15–140 kDa ranges using 3–10 non-linear IPG strips and Brilliant Blue Coomassie. Ten proteins were characterized as immunogenic proteins, seven of them were identified and three of them were unknown proteins.

Conclusion:

This study provided additional information about the somatic antigens of T. cati, which can lead to the development of new strategies for novel immuno-modulators, drug targets, subunit vaccines and immunodiagnostic kits for toxocariasis.

An optical aptasensor for aflatoxin M1 detection based on target-induced protection of gold nanoparticles against salt-induced aggregation and silica nanoparticles

Not only intoxications of aflatoxins are significant risk for human beings, but also; the contamination with these toxins affect the economy. Therefore, developing a rapid, precise and inexpensive determination method is vitally important. Here, a colorimetric aptasensor is introduced for the detection of aflatoxin M₁ (AFM₁) based on the preservation of gold nanoparticles (AuNPs) against NaCl-induced aggregation by detaching of complementary strand of aptamer (CS) from the aptamer-modified streptavidin coated silica nanoparticles (SNPs) following the addition of target. So, the color of sample remains red. While, in the lack of AFM₁, salt-induced aggregation of AuNPs occurs and the color of sample becomes purple as the aptamer/CS (dsDNA)-modified SNPs is stable and CS cannot bind to AuNPs. The proposed aptasensor could detect AFM₁ in a linear dynamic range, 300-75,000 ng/L, with a detection limit of 30 ng/L. Also, the sensing method was effectively applied for AFM₁ recognition in milk samples.

A fluorescent sensing strategy for ultrasensitive detection of oxytetracycline in milk based on aptamer-magnetic bead conjugate, complementary strand of aptamer and PicoGreen

Misuse of antibiotics in animal husbandry and presence of their residues in animal foods is a serious crisis worldwide and thus, monitoring the level of them in food samples is vital for human health. Herein, a fluorescent aptasensor was developed for highly sensitive quantification of oxytetracycline (OTC) in food samples. This method is based on OTC aptamer conjugated to magnetic beads, functioned as recognition element, complementary strand of OTC aptamer, and PicoGreen (PG) as a sensitive double-stranded DNA (dsDNA) fluorescent dye. Formation of OTC aptamer-magnetic bead conjugate provides the opportunity of sample condensation and separation technology. Additionally, the presence of complementary strand leads to significant fluorescence signal alteration of aptasensor in the presence or absence of target and a noteworthy improvement of the aptasensor sensitivity. In the absence of target, complementary strand could bind to aptamer and form dsDNA on the surface of magnetic bead. As a consequence, adding PG to the sample leads to observation of high fluorescence signal from sample. In contrast, once OTC is added to the sample, it binds to OTC aptamer-magnetic bead complex and prevents hybridization of OTC aptamer and its complementary strand. Hence, after addition of PG to the sample, a weak fluorescence intensity is measured. Under optimized conditions, the linear ranges for OTC detection were 0.2-2 nM and 2-800 nM. The detection limit was calculated to be as low as 0.15 nM for the fabricated aptasensor. Besides the great sensitivity, proposed method demonstrated superior specificity towards OTC once it was used against several antibiotics. More significantly, the recovery rates of OTC in milk ranged from 96.46% to 101.5%, implying the great feasibility of designed sensor as well as its potential to be employed for analysis of OTC in real samples.

Design and synthesis of a new magnetic metal organic framework as a versatile platform for immobilization of acidic catalysts and CO2 fixation reaction

The first report of the use of an acidic magnetic metal organic framework for the chemical fixation of CO2 as an environmentally friendly reaction.

Smart metal organic frameworks: focus on cancer treatment

Metal–organic frameworks (MOFs), as a prominent category of hybrid porous materials, have been broadly employed as controlled systems of drug delivery due to their inherent interesting properties.

A Novel Fluorescent Aptasensor for Sensitive Detection of Oxytetracycline Based on Gold Nanoparticles and OTC-Eu3+ Complex Using Two Different Methods for Modification of Gold Nanoparticles

We developed a simple and selective fluorescent aptasensor for the detection of oxytetracycline (OTC) using aptamer-conjugated gold nanoparticles (AuNPs) and a complex formed between oxytetracycline and a europium cation. In this study, AuNPs were modified with an OTC aptamer using two methods (Tween and NaCl methods). In the absence of OTC, an OTC-Eu3+ complex binds to the aptamer in the aptamer-conjugated AuNPs to give weak fluorescence emission. However, in the presence of OTC, the aptamer interacts with its target, causing a strong fluorescence emission. Under optimum conditions, the designed method showed high selectivity for OTC and a good linear range to OTC concentration from 15 to 500 nM with a limit of detection (LOD) of 10.6 nM for the NaCl method and linear range over 15–500 nM with an LOD of 8.8 nM for the Tween method. This biosensor was successfully employed to quantify OTC in milk and tablet samples.

CRISPR-cas9 genome editing delivery systems for targeted cancer therapy

The prokaryotic CRISPR-Cas systems could be applied as revolutionized genome editing tool in live cells of various species to modify, visualize and identify definite sequences of DNA and RNA. CRISPR-Cas could edit the genome by homology-directed repair and non-homologous end joining mechanisms. Furthermore, DNA-targeting modification by CRISPR-Cas methodology provides opportunity for diagnosis, therapy and the genetic disorders investigation. Here, we summarized delivery systems employed for CRISPR-Cas9 for genome editing. Then preclinical studies of the CRISPR-Cas9-based therapeutics will be discussed considering the associated challenges and developments in its translation to clinic for cancer therapy.

5'-Adenosine monophosphate deaminase regulation in ground squirrels during hibernation

Hibernation is an important winter survival strategy for many small mammals. By sinking into a deep torpor where metabolic rate can be as low as 1-5% of the resting rate in euthermia, animals accrue huge energy savings that allow survival, typically without eating, for many months. Hibernating ground squirrels show a net reduction in the total adenylate pool of skeletal muscle during torpor, but the ATP/ADP ratio and adenylate energy charge remain stable. A key enzyme involved in managing adenylate pool size is 5'-adenosine monophosphate deaminase (AMPD). Assessing skeletal muscle AMPD from both Richardson's ground squirrels (Urocitellus richardsonii) (RGS) and 13-lined ground squirrels (Ictidomys tridecemlineatus) (TLGS), the present study shows that muscle AMPD of euthermic versus hibernating animals displays markedly different kinetic properties, differential responses to temperature and to effectors, and is regulated by reversible protein phosphorylation. AMPD activity decreased during hibernation in both TLGS and RGS skeletal muscle, by 70 and 84%, respectively. Stimulation of total protein phosphatases, total serine/threonine protein phosphatases, PP1, PP2B or PP2C, all reduced AMPD activity between 54 and 92% in extracts of euthermic RGS muscle. The same incubation did not change the activity of AMPD from muscle of hibernating animals. Oppositely, both euthermic and hibernating AMPD showed a strong increase in activity when incubated under conditions that promoted the enzyme phosphorylation by PKA, PKC or PKG. Overall, the data indicate that both low activity of AMPD and low affinity of the enzyme for AMP during torpor reduce the rate of adenylate degradation, the primary driver of these changes being covalent phosphorylation of AMPD.

Co-delivery of doxorubicin and aptamer against Forkhead box M1 using chitosan-gold nanoparticles coated with nucleolin aptamer for synergistic treatment of cancer cells

Herein, a nanotherapeutic delivery method was presented for co-delivery of doxorubicin (DOX) and aptamer against Forkhead box M1 (FOXM1 Apt) to cancer cells. Firstly, the vehicle composed of chitosan (CS)-Gold nanoparticles (AuNPs) conjugate was prepared. Nucleolin aptamer (AS1411) and FOXM1 Apt were loaded onto the CS-AuNPs and formed Aptamers (Apts)-CS-AuNPs. Subsequently, DOX was added to the Apts-CS-AuNPs to obtain the DOX-Apts-CS-AuNPs complex for synergistic treatment of tumor. The data of flow cytometry analysis and fluorescence imaging displayed that the complex was effectively internalized into target cells (A549 and 4T1 cells, nucleolin+) but not into CHO cells as nontarget cells. The results of the MTT assay showed that the complex significantly increased cell mortality in 4T1 and A549 cells compared to CHO cells treated with the complex. The in vivo studies demonstrated that the DOX-Apts-CS-AuNPs complex exhibited more tumor inhibitory effect and less distribution in other organs compared to free DOX.