Optimisation of an Electrochemical DNA Sensor for Measuring KRAS G12D and G13D Point Mutations in Different Tumour Types

Nanomedicine Innovations for Lung Cancer Diagnosis and Therapy

Lung cancer remains a challenge within the realm of oncology. Characterized by late-stage diagnosis and resistance to conventional treatments, the currently available therapeutic strategies encompass surgery, radiotherapy, chemotherapy, immunotherapy, and biological therapy; however, overall patient survival remains suboptimal. Nanotechnology has ushered in a new era by offering innovative nanomaterials with the potential to precisely target cancer cells while sparing healthy tissues. It holds the potential to reshape the landscape of cancer management, offering hope for patients and clinicians. The assessment of these nanotechnologies follows a rigorous evaluation process similar to that applied to chemical drugs, which includes considerations of their pharmacokinetics, pharmacodynamics, toxicology, and clinical effectiveness. However, because of the characteristics of nanoparticles, standard toxicological tests require modifications to accommodate their unique characteristics. Effective therapeutic strategies demand a profound understanding of the disease and consideration of clinical outcomes, physicochemical attributes of nanomaterials, nanobiointeractions, nanotoxicity, and regulatory compliance to ensure patient safety. This review explores the promise of nanomedicine in lung cancer treatment by capitalizing on its unique physicochemical properties. We address the multifaceted challenges of lung cancer and its tumor microenvironment and provide an overview of recent developments in nanoplatforms for early diagnosis and treatment that can enhance patient outcomes and overall quality of life.

An Electrochemical Nucleic Acid Biosensor for Triple-Negative Breast Cancer Biomarker Detection

Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, affecting younger women and women of minorities. The nomenclature "triple negative" is derived from the absence of the three most common breast cancer biomarkers: progesterone receptor (PR), estrogen receptor (ER), and human epidermal growth factor receptor 2 (HER2). It derives its name from testing negative for these three most common breast cancer biomarkers. Currently, TNBC is diagnosed at advanced stages, necessitating the need for a diagnostic tool or method to identify this malignancy at an early stage prior to metastasis. In this study, a novel electrochemical biosensor was developed, optimized, and evaluated for the detection of microRNA-10b (miRNA-10b), marking the first use of this biomarker for the early diagnosis of TNBC. The biosensor demonstrated the ability to detect concentrations as low as 10 pM. Furthermore, the biosensor was specific toward the target biomarker, distinguishing non-target miRNAs of similar size. The efficacy of the biosensor for TNBC early diagnosis was further validated using human serum samples.

Singlet oxygen-based photoelectrochemical detection of single-point mutations in the KRAS oncogene

Single nucleotide point mutations in the KRAS oncogene occur frequently in human cancers, rendering them intriguing targets for diagnosis, early detection and personalized treatment. Current detection methods are based on polymerase chain reaction, sometimes combined with next-generation sequencing, which can be expensive, complex and have limited availability. Here, we propose a novel singlet oxygen (1O2)-based photoelectrochemical detection methodology for single-point mutations, using KRAS mutations as a case study. This detection method combines the use of a sandwich assay, magnetic beads and robust chemical photosensitizers, that need only air and light to produce 1O2, to ensure high specificity and sensitivity. We demonstrate that hybridization of the sandwich hybrid at high temperatures enables discrimination between mutated and wild-type sequences with a detection rate of up to 93.9%. Additionally, the presence of background DNA sequences derived from human cell-line DNA, not containing the mutation of interest, did not result in a signal, highlighting the specificity of the methodology. A limit of detection as low as 112 pM (1.25 ng/mL) was achieved without employing any amplification techniques. The developed 1O2-based photoelectrochemical methodology exhibits unique features, including rapidity, ease of use, and affordability, highlighting its immense potential in the field of nucleic acid-based diagnostics.

Electrochemical nucleic acid sensors: Competent pathways for mobile molecular diagnostics

Electrochemical nucleic acid biosensor has demonstrated great promise in clinical diagnostic tests, mainly because of its flexibility, high efficiency, low cost, and easy integration for analytical applications. Numerous nucleic acid hybridization-based strategies have been developed for the design and construction of novel electrochemical biosensors for diagnosing genetic-related diseases. This review describes the advances, challenges, and prospects of electrochemical nucleic acid biosensors for mobile molecular diagnosis. Specifically, the basic principles, sensing elements, applications in diagnosis of cancer and infectious diseases, integration with microfluidic technology and commercialization are mainly included in this review, aiming to provide new insights and directions for the future development of electrochemical nucleic acid biosensors.

Nucleotide-selective amplification and array-based detection for identifying multiple somatic mutations

In the context of personalized and cost-effective treatment, knowledge of the mutational status of specific genes is advantageous to predict which patients are responsive to therapies. As an alternative to one-by-one detection or massive sequencing, the presented genotyping tool determines multiple polymorphic sequences that vary a single nucleotide. The biosensing method includes an effective enrichment of mutant variants and selective recognition by colorimetric DNA arrays. The proposed approach is the hybridization between sequence-tailored probes and products from PCR with SuperSelective primers to discriminate specific variants in a single locus. A fluorescence scanner, a documental scanner, or a smartphone captured the chip images to obtain spot intensities. Hence, specific recognition patterns identified any single-nucleotide change in the wild-type sequence overcoming qPCR methods and other array-based approaches. Studied mutational analyses applied to human cell lines provided high discrimination factors, the precision was 95%, and the sensitivity was 1% mutant of total DNA. Also, the methods showed a selective genotyping of the KRAS gene from tumorous samples (tissue and liquid biopsy), corroborating results by NGS. The developed technology supported on low-cost robust chips and optical reading provides an attractive pathway toward implementing fast, cheap, reproducible discrimination of oncological patients.

Electrochemical biosensors for analysis of DNA point mutations in cancer research

Cancer is a genetic disease induced by mutations in DNA, in particular point mutations in important driver genes that lead to protein malfunctioning and ultimately to tumorigenesis. Screening for the most common DNA point mutations, especially in such genes as TP53, BRCA1 and BRCA2, EGFR, KRAS, or BRAF, is crucial to determine predisposition risk for cancer or to predict response to therapy. In this review, we briefly depict how these genes are involved in cancer, followed by a description of the most common techniques routinely applied for their analysis, including high-throughput next-generation sequencing technology and less expensive low-throughput options, such as real-time PCR, restriction fragment length polymorphism, or high resolution melting analysis. We then introduce benefits of electrochemical biosensors as interesting alternatives to the standard methods in terms of cost, speed, and simplicity. We describe most common strategies involved in electrochemical biosensing of point mutations, relying mostly on PCR or isothermal amplification techniques, and critically discuss major challenges and obstacles that, until now, prevented their more widespread application in clinical settings.

Reverse Electrochemical Sensing of FLT3-ITD Mutations in Acute Myeloid Leukemia Using Gold Sputtered ZnO-Nanorod Configured DNA Biosensors

Detection of genetic mutations leading to hematological malignancies is a key factor in the early diagnosis of acute myeloid leukemia (AML). FLT3-ITD mutations are an alarming gene defect found commonly in AML patients associated with high cases of leukemia and low survival rates. Available diagnostic assessments for FLT3-ITD are incapable of combining cost-effective detection platforms with high analytical performances. To circumvent this, we developed an efficient DNA biosensor for the recognition of AML caused by FLT3-ITD mutation utilizing electrochemical impedance characterization. The system was designed by adhering gold-sputtered zinc oxide (ZnO) nanorods onto interdigitated electrode (IDE) sensor chips. The sensing surface was biointerfaced with capture probes designed to hybridize with unmutated FLT3 sequences instead of the mutated FLT3-ITD gene, establishing a reverse manner of target detection. The developed biosensor demonstrated specific detection of mutated FLT3 genes, with high levels of sensitivity in response to analyte concentrations as low as 1 nM. The sensor also exhibited a stable functional life span of more than five weeks with good reproducibility and high discriminatory properties against FLT3 gene targets. Hence, the developed sensor is a promising tool for rapid and low-cost diagnostic applications relevant to the clinical prognosis of AML stemming from FLT3-ITD mutations.

Rapid Multiplex Strip Test for the Detection of Circulating Tumor DNA Mutations for Liquid Biopsy Applications

In the era of personalized medicine, molecular profiling of patient tumors has become the standard practice, especially for patients with advanced disease. Activating point mutations of the KRAS proto-oncogene are clinically relevant for many types of cancer, including colorectal cancer (CRC). While several approaches have been developed for tumor genotyping, liquid biopsy has been gaining much attention in the clinical setting. Analysis of circulating tumor DNA for genetic alterations has been challenging, and many methodologies with both advantages and disadvantages have been developed. We here developed a gold nanoparticle-based rapid strip test that has been applied for the first time for the multiplex detection of KRAS mutations in circulating tumor DNA (ctDNA) of CRC patients. The method involved ctDNA isolation, PCR-amplification of the KRAS gene, multiplex primer extension (PEXT) reaction, and detection with a multiplex strip test. We have optimized the efficiency and specificity of the multiplex strip test in synthetic DNA targets, in colorectal cancer cell lines, in tissue samples, and in blood-derived ctDNA from patients with advanced colorectal cancer. The proposed strip test achieved rapid and easy multiplex detection (normal allele and three major single-point mutations) of the clinically relevant KRAS mutations in ctDNA in blood samples of CRC patients with high specificity and repeatability. This multiplex strip test represents a minimally invasive, rapid, low-cost, and promising diagnostic tool for the detection of clinically relevant mutations in cancer patients.

Stimuli-Induced Upgrade of Nuclease-Resistant DNA Nanostructure Composed of a Single Molecular Beacon for Detecting Mutant Genes

As a kind of cell-free DNA in the bloodstream liberated from tumor cells, circulating tumor DNAs (ctDNAs) have been recognized as promising biomarkers in the field of early cancer diagnosis. However, robust, sensitive, and accurate detection of ctDNA in serum remains extremely challenging, especially toward the mutant KRAS gene, one of the most frequently mutated genes. Although DNA oligonucleotides as emerging practical signaling materials have been developed as sensitive and accurate tools, some intrinsic defects need to be overcome, such as fragility in complex biological environments. In this work, on the basis of the hydrophilicity-promoted assembly, a core/shell DNA nanostructure (DNS-MB) probe is constructed from only one hairpin-shaped probe (cholesterol-modified palindromic molecular beacon, Chol-PMB) for the amplification detection of KRAS mutation in serum without the need for any auxiliary probe. Chol-PMB is designed to recognize target DNA and serve as a polymerization primer and template, and thus target species can initiate polymerization-based strand displacement amplification (SDA). Moreover, target DNA is able to induce further aggregation of DNS-MB particles due to the enzymatic cross-linking effect, leading to a structural upgrade. The DNS-MB probe exhibits a detection limit of 50 fM and a wide quantitative range (from 50 fM to 160 nM). In addition, single nucleotide polymorphisms can be discriminated, such as mutant KRAS G12D (KRAS-M), providing a desirable platform for screening ctDNAs. More excitingly, because the termini of DNA components are hidden inward from nuclease attack, DNS-MB circumvents a false-positive signal even in freshly sampled serum and is suitable for application in the complex biological milieu. As a proof of concept, the DNS-MB probe is expected to provide useful insight into the development of simple and degradation-resistant DNA probes for substantially amplified detection of ctDNAs in complex serum, showing potential applications in the field of early tumor diagnosis.