Detection of large deletion in human BRCA1 gene in human breast carcinoma MCF-7 cells by using DNA-Silver Nanoclusters

Fluorescence self-assembled DNA hydrogel for the determination of prostate specific antigen by aggregation induced emission

In this study, an aptamer-based, functionalized-DNA hydrogel system is developed for prostate-specific antigen (PSA) detection. A pure DNA hydrogel is constructed using specific DNA building blocks and an aptamer as a cross-linker. Firstly, silver nanoclusters (AgNCs) are constructed on the Y-shaped DNA (Y-DNA) building blocks. Then, the DNA hydrogel was formed via the addition of the cross-linker to the Y-DNA solution. In this case, the fluorescence emission of silver nanoclusters that have accumulated in the hydrogel increases due to aggregation-induced emission (AIE). The presence of PSA and its subsequent interaction with its specific aptamer dissolve the hydrogel structures, which leads to a low emission intensity. A great linear relationship was attained in this assay in the range of 0.05 to 8 ng mL-1 with a detection limit of 4.4 pg mL-1 for the detection of PSA. Additionally, the proposed aptasensor was successfully used to detect PSA in human serum samples. The recovery for different concentrations of PSA was in the range of 96.1% to 99.3%, and the RSD range was from 2.3% to 4.5%. Comparing our method to current ones in the field of PSA detection proves that our platform benefits from a simpler procedure, lower cost, and better efficiency, providing high potential for future clinical applications.

Nanotechnology: A Promising Approach for Cancer Diagnosis, Therapeutics and Theragnosis

Cancer remains the most devastating disease and the major cause of mortality worldwide. Although early diagnosis and treatment are the key approach in fighting against cancer, the available conventional diagnostic and therapeutic methods are not efficient. Besides, ineffective cancer cell selectivity and toxicity of traditional chemotherapy remain the most significant challenge. These limitations entail the need for the development of both safe and effective cancer diagnosis and treatment options. Due to its robust application, nanotechnology could be a promising method for in-vivo imaging and detection of cancer cells and cancer biomarkers. Nanotechnology could provide a quick, safe, cost-effective, and efficient method for cancer management. It also provides simultaneous diagnosis and treatment of cancer using nano-theragnostic particles that facilitate early detection and selective destruction of cancer cells. Updated and recent discussions are important for selecting the best cancer diagnosis, treatment, and management options, and new insights on designing effective protocols are utmost important. This review discusses the application of nanotechnology in cancer diagnosis, therapeutics, and theragnosis and provides future perspectives in the field.

Design of Smart Nanomedicines for Effective Cancer Treatment

Nanomedicine is a novel field of study that involves the use of nanomaterials to address challenges and issues that are associated with conventional therapeutics for cancer treatment including, but not limited to, low bioavailability, low water-solubility, narrow therapeutic window, nonspecific distribution, and multiple side effects of the drugs. Multiple strategies have been exploited to reduce the nonspecific distribution, and thus the side effect of the active pharmaceutical ingredients (API), including active and passive targeting strategies and externally controllable release of the therapeutic cargo. Site-specific release of the drug prevents it from impacting healthy cells, thereby significantly reducing side effects. API release triggers can be either externally applied, as in ultrasound-mediated activation, or induced by the tumor. To rationally design such nanomedicines, a thorough understanding of the differences between the tumor microenvironment versus that of healthy tissues must be pared with extensive knowledge of stimuli-responsive biomaterials. Herein, we describe the characteristics that differentiate tumor tissues from normal tissues. Then, we introduce smart materials that are commonly used for the development of smart nanomedicines to be triggered by stimuli such as changes in pH, temperature, and enzymatic activity. The most recent advances and their impact on the field of cancer therapy are further discussed.

Suboptimal folic acid exposure rewires oncogenic metabolism and proteomics signatures to mediate human breast cancer malignancy

Whether treatment with folic acid (FA) affects human breast cancer positively or negatively remains unclear. We subjected human MCF-7 cells, a human breast cancer cell line, to suboptimal FA at low levels (10 nM; LF) and high levels (50 μM; HF) and investigated the molecular mechanisms underlying their effects through metabolic flux and systematic proteomics analyses. The data indicated that LF induced and HF aggravated 2-fold higher mitochondrial toxicity in terms of suppressed oxidative respiration, increased fermented glycolysis, and enhanced anchorage-independent oncospheroid formation. Quantitative proteomics and Gene Ontology enrichment analysis were used to profile LF- and HF-altered proteins involved in metabolism, apoptosis, and malignancy pathways. Through STRING analysis, we identified a connection network between LF- and HF-altered proteins with mTOR. Rapamycin-induced blockage of mTOR complex 1 (mTORC1) signaling, which regulates metabolism, differentially inhibited LF- and HF-modulated protein signatures of mitochondrial NADH dehydrogenase ubiquinone flavoprotein 2, mitochondrial glutathione peroxidase 4, kynureninase, and alpha-crystallin B chain as well as programmed cell death 5 in transcript levels; it subsequently diminished apoptosis and oncospheroid formation in LF/HF-exposed cells. Taken together, our data indicate that suboptimal FA treatment rewired oncogenic metabolism and mTORC1-mediated proteomics signatures to promote breast cancer development.

Highly selective and rapid detection of silver ions by using a "turn on" non-fluorescent cysteine stabilized gold nanocluster probe

Cysteine is widely used as a stabilizer for the preparation of fluorescent gold nanoclusters (Au NCs) with different fluorescence properties. Herein, by using cysteine as a stabilizer and controlling the synthesis conditions, a new non-fluorescent cysteine stabilized gold nanocluster (Cys-Au NCs) probe was prepared and a new strategy for "turning on" the fluorescence of the Cys-Au NCs was studied for rapid and selective detection of silver ions. In this strategy, the addition of silver ions to non-fluorescent Cys-Au NCs solution could quickly induce a visible fluorescence "turn on" phenomenon in 30 s. Further studies indicated that this fluorescence "turn on" phenomenon is specific for silver ions and the "turn on" fluorescence intensity has a linear relationship with the amount of silver ions in the range from 3.0 to 30.0 μM. Therefore, the non-fluorescent Cys-Au NCs were applied to the detection of silver ions in environmental water samples and a limit of detection (LOD) of 0.26 μM was obtained. This research sheds light on new applications of Au NCs and proposes a simple, rapid, sensitive, and visual method for the detection of metal ions.

Fluorometric determination of the breast cancer 1 gene based on the target-induced conformational change of a DNA template for copper nanoclusters

The breast cancer 1 (BRCA1) gene is a tumor suppressor gene, whose mutation is closely related to breast cancer. Therefore, the sensitive detection of the BRCA1 gene is extremely important for human health, particularly for women. In this study, a label-free fluorescent method based on hairpin DNA-templated copper nanoclusters (CuNCs) was for the first time developed for the detection of the BRCA1 gene. In the absence of target DNA, the detection system showed a strong red emission and produced a high emission peak. However, in the presence of the BRCA1 gene, the DNA probe hybridized with the BRCA1 gene and conformation of the DNA probe changed. As a result, the amount of produced CuNCs decreased and a low emission peak was obtained. The fluorescence intensity of the detection system was linearly correlated with the concentration of the BRCA1 gene ranging from 2 nM to 600 nM. The detectable limit was 2 nM for the BRCA1 gene assay, which was comparable with those reported by other non-amplifying sensors. Moreover, the developed method showed satisfactory recoveries for the BRCA1 gene assay in the bovine serum. The DNA-templated CuNC-based fluorescent assay thus offered a promising platform for the diagnosis of a breast cancer biomarker.

Nanotechnology in cancer diagnosis: progress, challenges and opportunities

In the fight against cancer, early detection is a key factor for successful treatment. However, the detection of cancer in the early stage has been hindered by the intrinsic limits of conventional cancer diagnostic methods. Nanotechnology provides high sensitivity, specificity, and multiplexed measurement capacity and has therefore been investigated for the detection of extracellular cancer biomarkers and cancer cells, as well as for in vivo imaging. This review summarizes the latest developments in nanotechnology applications for cancer diagnosis. In addition, the challenges in the translation of nanotechnology-based diagnostic methods into clinical applications are discussed.

Aptamer-based colorimetric determination of early-stage apoptotic cells via the release of cytochrome c from mitochondria and by exploiting silver/platinum alloy nanoclusters as a peroxidase mimic

An enzyme-free aptameric nanosensor is presented for apoptosis assay. The method exploits the peroxidase-mimicking property of silver/platinum alloy nanoclusters (Ag/Pt NCs) and uses a Cyt c binding ssDNA aptamer. An extra-strand polycytosine (C₁₄) aptamer was designed as a template for synthesis of the Ag/Pt NCs. If cell lysate or purified Cyt c is placed in a polystyrene microplate, Cyt c will bind to the surface of the wells of a microtiterplate. On addition of Apt@Ag/PtNCs, it will associate with Cyt c and then catalytically oxidize colorless tetramethylbenzidine (TMB) in the presence of H₂O₂ to give a blue colored oxidation product (TMB_ox) due to the peroxidase-mimicking property of the Ag/Pt NCs. Under optimal conditions, the absorbance of TMB at 660 nm is linearly enhanced as the concentration of Cyt c increases from 50.0 fM to 500 nM, and the detection limit is ~10 pM. The assay is simple, sensitive and cost effective in that it is enzyme-free, antibody-free and label-free. Graphical abstractSchematic diagram of the apoptosis assay on the basis of microplate well-coated mitochondrial cytochrome c releasing by using Aptamer@Ag/Pt NCs.

Glucose Sensor Using Redox Active Oligonucleotide-Templated Silver Nanoclusters

Redox active, photoluminescent silver nanoclusters templated with oligonucleotides were developed for glucose sensing. The silver nanoclusters had a photoluminescent emission at 610 nm that reversibly changed to 530 nm upon oxidation. The reversible emission change was measured with photoluminescent spectroscopy and used to detect H₂O₂, which is a by-product of the reaction of glucose with glucose oxidase. The ratio of the un-oxidised emission peak (610 nm) and the oxidised analogue (530 nm) was used to measure glucose concentrations up to 20 mM, well within glucose levels found in blood. Also, the reversibility of this system enables the silver nanoclusters to be reused.

Fluorescent C-NanoDots for rapid detection of BRCA1, CFTR and MRP3 gene mutations

The authors report on a fluorometric method for the rapid detection of BRCA1, CFRT and MRP3 gene mutations. These are associated with breast cancer, cystic fibrosis and autoimmune hepatitis diseases, respectively. Carbon nanodots with blue fluorescence (with excitation/emission maxima at 340/440 nm) were synthesized and characterized, and their interactions with DNA were investigated. Changes in the fluorescence intensity following interaction with ssDNA and dsDNA were used for specific DNA sequence of BRCA1, CFRT and MRP3 genes detection. The response to DNAs is linear up to 200 nM and the detection limit is 270 pM. The assay selectivity allows the detection of single gene mutations. Under optimum conditions, the assay can rapidly discriminate between wild type and mutated samples. Graphical abstract Schematic representation of fluorescence assay for rapid detection of gene mutation based on fluorescent carbon nanodots.

A colorimetric paper sensor for citrate as biomarker for early stage detection of prostate cancer based on peroxidase-like activity of cysteine-capped gold nanoclusters

Citrate is currently considered a preferred biomarker for the early stage detection of prostate cancer. In the present work, based on the highly efficient catalytic properties of gold nanoclusters, a novel system for optical determination of citrate was successfully established under optimized conditions. Cysteine-capped gold nanoclusters (Cys-AuNCs) are shown to have an intrinsic peroxidase-mimetic activity. In the presence of H₂O_2, Cys-AuNCs nanostructures are able to catalyse the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) with high efficiency to produce a blue dye (with an absorbance maximum at 650 nm). Citrate has carboxylic and hydroxyl groups that can bind with free amino and free carboxyl cysteine groups via hydrogen bonds, thus creating a coating on the surface of the gold nanocluster and inhibiting the cluster oxidation activity. Accordingly, a visual, sensitive and simple colorimetric method using Cys-AuNCs as peroxidase mimetic was developed for detecting citrate. A suitable linear relationship for citrate was obtained for the range of 0.5 to 1000 μM. The limit of detection (LOD) of the proposed method was calculated as 0.1 μM and the relative standard deviation (RSD) was obtained to be less than 4.0%. Moreover, the biosensor was used to perform a paper assay on a Y-shaped microfluidic device and make use of the distinctive features of microchannels such as short response time, very low reagent volume required, low fabrication cost etc. A detection limit of 0.4 μM was achieved through the paper test and a good linear range was observed between 1.0 μM-10 mM. The proposed method was further applied to citrate detection in the human urine sample.

Optical absorption in complexes of abasic DNA with noble-metal nanoclusters by first principles calculations

Abasic sites (AP site) in a DNA duplex have been experimentally used to produce fluorescent Ag nanoclusters (NC) with a small number of atoms (n ≤ 6).