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

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.

Nucleolin, an RNA binding protein, is considered to be a target for developing cancer therapies and diagnostics. Herein, we have reported a designed nucleolin-targeted AS1411 aptamer conjugated to guanidinium groups of epibromohydrin functionalized TiO2@γ-Fe2O3 nanoparticles (AS1411@GMBS@EG@TiO2@Fe2O3, NP–Apt) to increase drug delivery in targeted tumor tissues. The structure and morphology of the obtained NPs were characterized by FT-IR, VSM, EDX, HRTEM, and TEM analysis. Doxorubicin (DOX) was entrapped in NP–Apt (NP–Apt–DOX) with an entrapment efficiency of 47.59 ± 3.98%. NP–Apt–DOX revealed homogeneous characteristics with narrow particle size distributions. The in vitro drug release of NP–Apt–DOX was pH-dependent with initial rapid release (within 6 h) followed by sustained release for 72 h. Fluorescence microscopy and MTT assay were used to assess the cellular uptake and anti-proliferation activity of NP–Apt–DOX against nucleolin-positive (A375 and C26) cells. NP–Apt–DOX showed higher cellular uptake and more enhanced cytotoxicity in nucleolin-expressing cancer cells than in L929 fibroblasts as a nucleolin-negative cell line through increasing intracellular ROS levels. Significant tumor growth inhibition and prolonged animal survival were observed in mice bearing C26 colon carcinoma treated with NP–Apt–DOX. Overall, AS1411@GMBS@EG@TiO2@Fe2O3 is a pH-responsive sustained release system and offers promise as an effective and safe system for targeted drug delivery.

Herein, a sensitive and rapid fluorescent aptasensor was developed for the detection of cocaine as an illicit drug, based on an amplification strategy involving the use of silica nanoparticles coated with streptavidin (SNPs), double quenching of FAM fluorophore and cocaine split aptamer. Presence of cocaine could trigger the formation of the double-fragment cocaine aptamer and bring TAMRA fluorophore near the SNP surface and FAM close to BHQ-1 and TAMRA, resulting in the enhancement of relative fluorescence signal (fluorescence intensity of TAMRA/fluorescence intensity of FAM). Under optimal conditions, the proposed aptasensor achieved a limit of detection (LOD) of 84 pM and a linear range of 500 pM to 80 nM for cocaine. The practical potential of the developed sensing platform was proved by the detection of cocaine in spiked human serum samples with satisfactory recoveries.

The clinical administration of epirubicin (Epi) in the treatment of cancer has been restricted, owing to its cardiotoxicity. Targeted delivery of anticancer agents could increase their therapeutic efficacy and decrease their off-target effects. In this study, a novel Epi-DNA diamond nanostructure (DDN) conjugate containing two kinds of aptamers (MUC1 and ATP aptamers) was designed and evaluated in the treatment of target cells, including C26 cells (murine colon carcinoma cell) and MCF-7 cells (breast cancer cell). DDN and Epi-DDN conjugate formations were analyzed by gel retardation assay and fluorometric analysis, respectively. Release profiles of Epi from the developed Epi-DDN conjugate were evaluated at pHs 5.4 and 7.4. For the MTT assay (cell viability study), CHO cells (Chinese hamster ovary cell, nontarget), C26 and MCF-7 cells (target) were treated with the Epi-DDN conjugate, DDN, Epi, Epi-DDN conjugate without ATP aptamer and Epi-DDN conjugate without MUC1 aptamer. Internalization of the Epi-DDN conjugate was assessed by flow cytometry analysis and fluorescence imaging. Finally, the designed Epi-DDN conjugate was utilized for inhibition of tumor growth in vivo. 10 μM Epi was efficiently loaded in 1 μM DDN. The drug was released from the Epi-DDN conjugate in a pH-sensitive manner (higher release in acidic conditions). The results of flow cytometry analysis and fluorescence imaging confirmed that the developed Epi-DDN conjugate was effectively internalized into target cells, but not into nontarget cells. The results of the MTT assay were consistent with the internalization data. The Epi-DDN conjugate had more cytotoxicity in MCF-7 and C26 cells and less cytotoxicity in CHO cells in comparison with Epi alone. Moreover, the Epi-DDN conjugate could effectively prohibit tumor growth in vivo.

Clinical application of vincristine in treatment of cancer is restricted because of its poor solubility and neuropathy. Targeted delivery of cytotoxic drugs could improve their therapeutic efficacy and reduce their severe side effects. Biocompatibility and high accumulation of human serum albumin nanoparticles (HSA) in tumors make this substance an ideal candidate for biomedical usage. Here, a Vincristine–HSA–Sgc8c aptamer (Apt) complex was designed and assessed for the treatment of Molt-4 cells (human acute lymphoblastic leukemia T-cell, target). Vincristine–HSA conjugate and Vincristine–HSA–Apt complex formations were analyzed by particle size analyzer, transmission electron microscopy (TEM) and gel retardation assay. Internalization of the Vincristine–HSA–FAM (3′-fluorescein)-labeled Apt complex into Molt-4 (target) and U266 cells (B lymphocyte human myeloma, nontarget) was monitored by confocal imaging and flow cytometry analysis. For cell viability (MTT assay), both cell lines were treated with vincristine, Vincristine–HSA conjugate, HSA–Apt conjugate and Vincristine–HSA–Apt complex. Vincristine was efficiently loaded (8.5%) into HSA. The results of confocal imaging and flow cytometry analysis indicated that the Vincristine–HSA–FAM-labeled Apt complex was effectively internalized into target cells (Molt-4) but not into nontarget cells (U266). The results of MTT assay also confirmed the internalization data. The Vincristine–HSA–Apt complex had less cytotoxicity in U266 cells compared to vincristine alone and Vincristine–HSA conjugate. In conclusion, the developed drug delivery system acquired properties of high drug loading, high cancer cell accumulation and cancer cell targeting.

A fluorescent aptasensor system has been designed for the sensitive detection of kanamycin based on silica nanoparticles (SNPs) coated with streptavidin. The kanamycin aptamer, which served as the molecular recognition probe, was immobilized on the surface of the SNPs. In the absence of kanamycin, the SNPdouble stranded DNA (dsDNA) complex is intact and has the maximum fluorescent signal. Upon addition of kanamycin, the aptamer binds to its target and causes the dissociation of the labeled-complementary strand from dsDNA and SNPs, leading to a decrease of the fluorescence intensity. This aptasensor exhibited a high sensitivity toward kanamycin with a limit of detection (LOD) as low as 612 pM. The designed aptasensor was successfully used to detect kanamycin in serum and a limit of detection as low as 453 pM was obtained. By changing the related aptamer strand and its complementary strand, it could be expected that the proposed method offers a general sensing platform for the recognition of trace amounts of different drugs and biomolecules.

Lead (Pb) is a serious environmental contaminant and one of the most toxic heavy metals. In this study a colorimetric aptasensor was designed for selective, sensitive and rapid detection of Pb2+, based on a triple-helix molecular switch (THMS) and peroxidase-like activity of gold nanoparticles (AuNPs). This sensor inherits the properties of THMS, including high stability and preserving the affinity and selectivity of the original aptamer and properties of peroxidase-like activity of AuNPs, such as fast readout and improvement of the sensitivity. In the absence of Pb2+, THMS is intact, leading to complete peroxidase-like activity of AuNPs and an obvious color change to purplish-blue. In the presence of Pb2+, the aptamer binds to Pb2+, the signal transduction probe (STP) leaves the THMS and adsorbs onto the surface of AuNPs, leading to inhibition of the peroxidase-like activity of AuNPs and no color change is observed. The designed aptasensor showed high selectivity toward Pb2+ with a limit of detection as low as 602 pM for Pb2+. The presented aptasensor was successfully used to detect Pb2+ in water and serum.

Digoxin is a useful drug in the treatment of heart failure. The therapeutic index of digoxin is very narrow. Thus, its detection in serum is of remarkable interest. In this study we designed a sensitive and selective fluorescent aptasensor for detection of digoxin based on silica nanoparticles (SNPs) coated with streptavidin. In the absence of digoxin, the fluorescence of the SNP–double stranded DNA (dsDNA) complex is strong. Upon addition of digoxin, the aptamer binds to its target, leading to release of the labeled-complementary strand from dsDNA and SNPs and decrease of the fluorescence intensity. This aptasensor showed a high selectivity toward digoxin and a limit of detection as low as 566 pM was obtained. This sensing platform is expected to be used successfully for detection of other drugs and biomolecules.

Tetracycline (TET) is one of the most extensively used antibiotics in humans and animals. Fast and sensitive measurement of TET is of great interest. In this study, a triple-helix molecular switch (THMS) was developed for TET detection. The THMS consists of a target specific aptamer sequence and a signal transduction probe (STP). In the presence of a target, the aptamer binds to TET and the THMS complex is disassembled; so that the free STP is folded to a stem loop structure, and the fluorescence is quenched. In the absence of TET, the fluorescence is on. This sensor showed a high selectivity toward TET and a limit of detection (LOD) as low as 2.09 nM was obtained. Furthermore, our fabricated sensor was successfully used for TET detection and quantification in tap water and rat serum. It is expected that this sensor could be extended for the detection of other drugs.

Digoxin is a cardiac glycoside with a narrow therapeutic index that is commonly used to treat heart failure. In this study, we designed selective, sensitive and fast fluorescence quenching and colorimetric aptasensors for the detection of digoxin based on aqueous gold nanoparticle (AuNP) suspension. In the absence of digoxin, aptamers are adsorbed on the surface of AuNPs. Therefore the well-dispersed AuNPs remain stable against salt-induced aggregation and the fluorescence of the ATTO 647N-aptamer is efficiently quenched by AuNPs. In the presence of digoxin, aptamers bind to digoxin, leading to the aggregation of AuNPs by salt, resulting in a color change from red to blue and recovery of the fluorescence emission. Fluorescence quenching and colorimetric aptasensors showed high selectivity toward digoxin with a limit of detection (LOD) as low as 392 and 571 pM, respectively. Our designed aptasensors were successfully used to detect digoxin in serum.