A label-free technique for accurate detection of nucleic acid-based self-avoiding molecular recognition systems supplemented multiple cross-displacement amplification and nanoparticles based biosensor

Biosensor-Based Multiple Cross Displacement Amplification for the Rapid Detection of Mycobacterium leprae

Leprosy is an ancient disease caused by Mycobacterium leprae (ML) that remains a public health problem in poverty-stricken areas worldwide. Although many ML detection techniques have been used, a rapid and sensitive tool is essential for the early detection and treatment of leprosy. Herein, we developed a rapid ML detection technique by combining multiple cross displacement amplification (MCDA) with a nanoparticle-based lateral flow biosensor (LFB), termed ML-MCDA-LFB. MCDA induced a rapid isothermal reaction using specific primers targeting the RLEP gene, and the LFB enabled instant visual amplicon detection. The pure genomic DNA of ML and nucleic acids from various pathogens were employed to evaluate and optimize the ML-MCDA-LFB assay. The optimal conditions for ML-MCDA-LFB were 68 °C and 35 min, respectively. The limit of detection for pure ML genomic DNA was 150 fg per vessel, and the specificity of detection was 100% for the experimental strains. Additionally, the entire detection process could be performed within 40 min, including the isothermal amplification (35 min) and result confirmation (1-2 min). Hence, the ML-MCDA-LFB assay was shown to be a rapid, sensitive, and visual method for detecting ML and could be used as a potential tool for early clinical diagnosis and field screening of leprosy.

Paeonol repurposing for cancer therapy: From mechanism to clinical translation

Paeonol (PAE) is a natural phenolic monomer isolated from the root bark of Paeonia suffruticosa that has been widely used in the clinical treatment of some inflammatory-related diseases and cardiovascular diseases. Much preclinical evidence has demonstrated that PAE not only exhibits a broad spectrum of anticancer effects by inhibiting cell proliferation, invasion and migration and inducing cell apoptosis and cycle arrest through multiple molecular pathways, but also shows excellent performance in improving cancer drug sensitivity, reversing chemoresistance and reducing the toxic side effects of anticancer drugs. However, studies indicate that PAE has the characteristics of poor stability, low bioavailability and short half-life, which makes the effective dose of PAE in many cancers usually high and greatly limits its clinical translation. Fortunately, nanomaterials and derivatives are being developed to ameliorate PAE's shortcomings. This review aims to systematically cover the anticancer advances of PAE in pharmacology, pharmacokinetics, nano delivery systems and derivatives, to provide researchers with the latest and comprehensive information, and to point out the limitations of current studies and areas that need to be strengthened in future studies. We believe this work will be beneficial for further exploration and repurposing of this natural compound as a new clinical anticancer drug.

Extraction of curcuminoids and ar-turmerone from turmeric (Curcuma longa L.) using hydrophobic deep eutectic solvents (HDESs) and application as HDES-based microemulsions

The extraction of curcuminoids and aromatic (ar)-turmerone from Curcuma longa L. using organic solvents produces chemical waste, and is therefore incompatible with food applications. To address this issue, this study presents the design of hydrophobic deep eutectic solvents (HDESs) and HDES-based microemulsions. Using the response surface methodology (RSM), the optimal extraction conditions were identified as follows: HDES = OA:menthol (1:3.6 M ratio), solid-to-liquid ratio = 10:1 (mg/mL), and extraction duration = 90 min (prediction accuracy ≥ 85 %). Under these conditions, the HDES extraction yields of bisdemethoxycurcumin, demethoxycurcumin, curcumin, and ar-turmerone were 2.49 ± 0.25, 5.61 ± 0.45, 9.40 ± 0.86, and 3.83 ± 0.19 % (w/w, dry basis), respectively, while those obtained using the HDES-based microemulsion were 2.10 ± 0.18, 6.31 ± 0.48, 12.6 ± 1.20, and 2.58 ± 0.19 % (w/w, dry basis), respectively. The HDES and its microemulsions are more effective and environmentally friendly than conventional organic solvents for the extraction of curcuminoids and ar-turmerone, and these solvents are also compatible with food and pharmaceutical formulations.

Development and Application of a Multiple Cross Displacement Amplification Combined With Nanoparticle-Based Lateral Flow Biosensor Assay to Detect Candida tropicalis

Candida tropicalis is an increasingly opportunistic pathogen that causes serious invasive candidiasis threatening a patient’s life. Traditional methods to detect C. tropicalis infection depends on time-consuming, culture-based gold-standard methods. So, we sought to establish a new method that could detect target pathogens quickly, accurately, and straightforwardly. Herein, a combination of multiple cross displacement amplification (MCDA) and lateral flow biosensors (LFB) was employed to detect C. tropicalis. In the MCDA system, 10 primers were designed to identify the specific genes of C. tropicalis and amplify the genes in an isothermal amplification device. Then, MCDA amplification reaction products could be identified visibly by color change, and all the amplification products would be tested by LFB with no special equipment. The results demonstrated that the optimal reaction condition of C. tropicalis-MCDA assay was 64°C within 30 min, and only 10 fg DNA was required in each reaction. No cross-reaction was found between C. tropicalis strains and non-C. tropicalis strains. For 300 sputum samples, the results showed that MCDA-LFB assay could rapidly and successfully detect all of the C. tropicalis-positive (28/300) samples detected by the gold-standard method. The entire procedure, including specimen processing (40 min), isothermal reaction (30 min) and result reporting (within 2 min), could be completed within 75 min. Briefly, the study results demonstrated that the detection ability of C. tropicalis-MCDA-LFB assay was better than culture methods with more simplicity, rapidity, sensitivity and specificity. Hence, MCDA-LFB strategy is an effective tool to rapidly detect C. tropicalis in clinical samples, especially in resource-poor areas.

Transdermal Delivery Systems of Natural Products Applied to Skin Therapy and Care

Natural products are favored because of their non-toxicity, low irritants, and market reacceptance. We collected examples, according to ancient wisdom, of natural products to be applied in transdermal delivery. A transdermal delivery system, including different types of agents, such as ointments, patches, and gels, has long been used for skin concerns. In recent years, many novel transdermal applications, such as nanoemulsions, liposomes, lipid nanoparticles, and microneedles, have been reported. Nanosized drug delivery systems are widely applied in natural product deliveries. Nanosized materials notably enhance bioavailability and solubility, and are reported to improve the transdermal permeation of many substances compared with conventional topical formulations. Natural products have been made into nanosized biomaterials in order to enhance the penetration effect. Before introducing the novel transdermal applications of natural products, we present traditional methods within this article. The descriptions of novel transdermal applications are classified into three parts: liposomes, emulsions, and lipid nanoparticles. Each section describes cases that are related to promising natural product transdermal use. Finally, we summarize the outcomes of various studies on novel transdermal agents applied to skin treatments.

Comparison of Multiple Displacement Amplification (MDA) and Multiple Annealing and Looping-Based Amplification Cycles (MALBAC) in Limited DNA Sequencing Based on Tube and Droplet

Whole genome amplification (WGA) is crucial for whole genome sequencing to investigate complex genomic alteration at the single-cell or even single-molecule level. Multiple displacement amplification (MDA) and multiple annealing and looping based amplification cycles (MALBAC) are two most widely applied WGA methods, which have different advantages and disadvantages, dependent on research objectives. Herein, we compared the MDA and MALBAC to provide more information on their performance in droplets and tubes. We observed that the droplet method could dramatically reduce the amplification bias and retain the high accuracy of replication than the conventional tube method. Furthermore, the droplet method exhibited higher efficiency and sensitivity for both homozygous and heterozygous single nucleotide variants (SNVs) at the low sequencing depth. In addition, we also found that MALBAC offered a greater uniformity and reproducibility and MDA showed a better efficiency of genomic coverage and SNV detection. Our results provided insights that will allow future decision making.

Current and Future Perspectives on Isothermal Nucleic Acid Amplification Technologies for Diagnosing Infections

Nucleic acid amplification technology (NAAT) has assumed a critical position in disease diagnosis in recent times and contributed significantly to healthcare. Application of these methods has resulted in a more sensitive, accurate and rapid diagnosis of infectious diseases than older traditional methods like culture-based identification. NAAT such as the polymerase chain reaction (PCR) is widely applied but seldom available to resource-limited settings. Isothermal amplification (IA) methods provide a rapid, sensitive, specific, simpler and less expensive procedure for detecting nucleic acid from samples. However, not all of these IA techniques find regular applications in infectious diseases diagnosis. Disease diagnosis and treatment could be improved, and the rapidly increasing problem of antimicrobial resistance reduced, with improvement, adaptation, and application of isothermal amplification methods in clinical settings, especially in developing countries. This review centres on some isothermal techniques that have found documented applications in infectious diseases diagnosis, highlighting their principles, development, strengths, setbacks and imminent potentials for use at points of care.

Sketching neoteric solvents for boosting drugs bioavailability

Emerging neoteric solvents are being the subject of growing attention due to their lower cost and environmental impact, so they are being applied in a broad spectrum of industries. Among them, the pharmaceutical sector is demanding new environmentally friendly and non-toxic solvents able to enhance drugs solubility and stability. The introduction of ionic liquids turned out to be a breakthrough in the field of Green Chemistry opening up new separation and catalysis opportunities. In this sense, the options represented by Deep Eutectic Solvents make up an attractive alternative due to the low cost of their raw material, simple synthesis, and eco-friendly character. In line with these findings, Therapeutic Deep Eutectic Solvents and Natural Deep Eutectic Solvents are new and promising alternatives to improve the bioavailability of drugs in pharmaceutical formulations. This leading article is focused on providing a general picture of the advantages and drawbacks of these new solvents as well as the main research lines and perspectives to achieve efficient drugs delivery systems.

Development of a multiple cross displacement amplification combined with nanoparticles-based biosensor assay to detect Neisseria meningitidis

BACKGROUND

Neisseria meningitidis is a leading pathogen of meningococcal disease in humans worldwide. Multiple cross displacement mplification (MCDA) combined with nanoparticles-based lateral flow biosensor (MCDA-LFB) has been reported for the rapid detection of several bacterial pathogens in recent years. Here, therefore we developed an MCDA-LFB assay for the rapid detection of N. meningitis.

METHODS

A set of 10 primers specifically to recognize 10 different regions of the ctrA gene of N. meningitidis were designed. MCDA was developed and combined with a LFB to detect the ctrA gene of N. meningitidis. The reaction time and temperature condition for the MCDA-LFB were optimized and then the MCDA-LFB was applied to detect the DNA from clinical samples.

RESULTS

MCDA-LFB assay was successfully established for the detection of N. meningitidis based on the ctrA gene. The MCDA assay was optimized at 64°C for only 35 mins and the products of amplification were directly sensed by LFB. The whole operation, including DNA template preparation (~20 mins), MCDA reaction (35 mins) and results interpretation (~2 mins) could be finished in no more than 60 mins. The detection limit was as low as 10 fg/reaction (around 3 CFUs/reaction) of pure N. meningitidis DNA, with no cross-reaction with other bacterial DNA.

CONCLUSION

The MCDA-LFB techniques developed in the present study are an effective tool for the rapid detection of N. meningitidis, especially in resource-poor countries in meningococcal disease epidemic period.

Bone morphogenetic protein signaling in breast cancer progression

Breast cancer is the most prevalent type of cancer amongst women worldwide. The mortality rate for patients with early-stage breast cancer has been decreasing, however, the 5-year survival rate for patients with metastatic disease remains poor, currently at 27%. Here, we have reviewed the current understanding of the role of bone morphogenetic protein (BMP) signaling in breast cancer progression, and have highlighted the discordant results that are reported in different studies. We propose that some of these contradictory outcomes may result from signaling through either the canonical or non-canonical pathways in different cell lines and tumors, or from different tumor-stromal interactions that occur in vivo.

Rapid Detection of Brucella spp. and Elimination of Carryover Using Multiple Cross Displacement Amplification Coupled With Nanoparticles-Based Lateral Flow Biosensor

Brucella spp.is capable of causing disease in a range of animal hosts, and human brucellosis is regarded as a life-threating disease. A novel isothermal amplification technique, termed multiple cross displacement amplification (MCDA), was employed for detecting all Brucella species strains. Brucella-MCDA targets the Bscp31 gene (Brucella species-specific gene) to specifically design a set of 10 primers. The Brucella-MCDA can be coupled with nanoparticles-based lateral flow biosensor (LFB) for highly specific, simple, rapid, and visual detection of Brucella-specific amplicons. Using the protocol, a MCDA amplification followed by 2 min LFB resulted in visualization of DNA products trapped at the LFB test line. Various species of Gram-positive and Gram-negative strains are applied for optimizing and evaluating the target assay. Optimal MCDA condition is found to be 63°C for 40 min, with detection limits at 10 fg of templates in the pure cultures. The specificity of MCDA-LFB technique is of 100%, and no cross-reactions to non-Brucella strains are observed according to the specificity examination. Furthermore, dUTP and AUDG enzyme are added into the MCDA reaction mixtures, which are used for removing false-positive amplification generating from carryover contamination. Thus, 20 min for rapid template extraction followed by AUDG digestion (5 min), MCDA (40 min) combined with LFB detection (2 min) resulted in a total assay time of ~70 min. In sum, Brucella-MCDA-LFB technique is a rapid, simple, reliable, and sensitive method to detect all Brucella species strains, and can be used as potential screening tool for Brucella strains in various laboratories.

Nanomaterials as potential and versatile platform for next generation tissue engineering applications

Tissue engineering (TE) is an emerging field where alternate/artificial tissues or organ substitutes are implanted to mimic the functionality of damaged or injured tissues. Earlier efforts were made to develop natural, synthetic, or semisynthetic materials for skin equivalents to treat burns or skin wounds. Nowadays, many more tissues like bone, cardiac, cartilage, heart, liver, cornea, blood vessels, and so forth are being engineered using 3-D biomaterial constructs or scaffolds that could deliver active molecules such as peptides or growth factors. Nanomaterials (NMs) due to their unique mechanical, electrical, and optical properties possess significant opportunities in TE applications. Traditional TE scaffolds were based on hydrolytically degradable macroporous materials, whereas current approaches emphasize on controlling cell behaviors and tissue formation by nano-scale topography that closely mimics the natural extracellular matrix. This review article gives a comprehensive outlook of different organ specific NMs which are being used for diversified TE applications. Varieties of NMs are known to serve as biological alternatives to repair or replace a portion or whole of the nonfunctional or damaged tissue. NMs may promote greater amounts of specific interactions stimulated at the cellular level, ultimately leading to more efficient new tissue formation. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 2433-2449, 2019.

Isothermal amplification and rapid detection of Klebsiella pneumoniae based on the multiple cross displacement amplification (MCDA) and gold nanoparticle lateral flow biosensor (LFB)

Klebsiella pneumoniae (K. pneumoniae) is a frequent pathogen causing nosocomial infections and outbreaks. We developed a multiple cross displacement amplification (MCDA) assay for the detection of K. pneumoniae, which can get the positive results within 40 minutes’ isothermal amplification. Gold-nanoparticle lateral flow biosensor (LFB) and colorimetric indicators were used for the rapid readouts of MCDA amplification. The detection limit of this assay was 100 fg per reaction at 65°C, which was confirmed to be the optimal amplification temperature according to the real time turbidimeters. For specificity, all of the 30 clinical-source K. pneumoniae strains were positive for the MCDA, and all of the non-K. pneumoniae strains belonging to 31 different species were negative for this MCDA assay. To evaluate the practical applicability of this method, we assessed its detection limit for K. pneumoniae strains in sputum samples (24 CFU per reaction), and DNA templates of 100 sputum samples further underwent the MCDA-LFB tests. All of the sputum samples being positive for K. pneumoniae (30/100) with the culture method were successfully identified with the MCDA assay, the detection power of which was higher than that of polymerase chain reaction (PCR) (25/100). Thus, the MCDA test for K. pneumoniae combined with the gold nanoparticle LFB as the results readout scheme, are simple, specific, and sensitive methods for the rapid diagnosis of K. pneumoniae in clinical samples.

TGF-β plays a vital role in triple-negative breast cancer (TNBC) drug-resistance through regulating stemness, EMT and apoptosis

Triple negative breast cancer (TNBC) is the most malignant subtype of breast cancer in which the cell surface lacks usual targets for drug to exhibit its effects. Epirubicin (Epi) is widely used for TNBC, but a substantial number of patients develop Epi resistance that is usually associated with poor prognosis. Transforming growth factor (TGF-β) is a multifunctional cytokine. In recent study, it appears that TGF-β influences the cancer stem cell population, thus, the drug resistance of cancer may also be affected. We used epirubicin to treat MDA-MB-231 (MB-231) cells and found that TGF-β and breast cancer stem cell markers CD44⁺CD24^- were increased and were dose-dependent of epirubicin. We established drug-resistant cell line from parental MB-231 cells by chronic treatment with low-concentration epirubicin. The MB-231/Epi cell line showed relatively slow growth rate with varied morphology. Transwell assay and drug sensitivity assay revealed that the malignant cell behaviors in terms of migration, invasion and epirubicin-resistant properties were markedly increased in the MB-231/Epi cells. Western blot, immunofluorescence assay, and flow cytometry were used to analyze the expression levels of the breast cancer stem cell markers, CD44 and CD24. Mammospheres assay showed that the stemness of MB-231/Epi was increased compared to their parental cells. Interestingly, MB-231/Epi cells showed different expression levels of apoptosis-related markers: Bcl2, Bax; EMT-related markers E-cadherin, N-cadherin and cell cycle-related marker cyclinD1. These genes have all been shown to be regulated by the TGF-β pathway. Taken together, our findings suggest that TGF-β plays a vital role in TNBC epirubicin-resistance through regulating stemness, EMT and apoptosis.

Multiple Cross Displacement Amplification Coupled With Nanoparticles-Based Lateral Flow Biosensor for Detection of Staphylococcus aureus and Identification of Methicillin-Resistant S. aureus

Staphylococcus aureus (S. aureus), including methicillin-resistant S. aureus (MRSA), is one of the most important human pathogens, which is responsible for bacteremia, soft-tissue infections, and food poisoning. Hence, multiple cross displacement amplification (MCDA) is employed to detect all S. aureus strains, and differentiates MRSA from methicillin-sensitive S. aureus. Multiplex MCDA (m-MCDA), which targets the nuc gene (S. aureus-specific gene) and mecA gene (encoding penicillin-binding protein-2′), could detect S. aureus strains and identify MRSA within 85 min. Detection of the m-MCDA products is achieved using disposable lateral flow biosensors. A total of 58 strains, including various species of Gram-positive and Gram-negative strains, are used for evaluating and optimizing m-MCDA assays. The optimal amplification condition is found to be 63°C for 40 min, with detection limits at 100 fg DNA/reaction for nuc and mecA genes in the pure cultures, and 10 CFU/tube for nuc and mecA genes in the blood samples. The analytical specificity of m-MCDA assay is of 100%, and no cross-reactions to non-S. aureus strains are produced according to the specificity testing. Particularly, two additional components, including AUDG enzyme and dUTP, are added into the m-MCDA amplification mixtures, which are used for eliminating the unwanted results arising from carryover contamination. Thus, the m-MCDA technique appears to be a simple, rapid, sensitive, and reliable assay to detect all S. aureus strains, and identify MRSA infection for appropriate antibiotic therapy.

Rapid, sensitive and reliable detection of Klebsiella pneumoniae by label-free multiple cross displacement amplification coupled with nanoparticles-based biosensor

Klebsiella pneumoniae (K. pneumoniae), as an important hospital-acquired bacterium, is responsible for severe morbidity and mortality among the elderly, newborn and immune-compromised people. We established a rcsA gene-based label-free multiple cross displacement amplification (MCDA) assay for rapid, simple and sensitive detection of K. pneumoniae by using lateral flow biosensor (LFB). MCDA reaction was conducted at a fixed temperature (65 °C) for only 30 min, and amplification results were directly indicated using LFB. The results showed that reaction products were detectable from as little as 100 fg and 4.8 CFU of pure K. pneumoniae templates, and from approximately 480 CFU in 1 mL of spiked clinical samples. All K. pneumoniae strains examined were positive for label-free MCDA-LFB analysis, and all non-K. pneumoniae strains used in the report were negative for label-free MCDA-LFB assay, indicating the high selectivity of the label free MCDA-LFB assay. Furthermore, to remove false-positive results, the label-free MCDA-LFB assay was supplemented with antarctic thermal sensitive uracil-DNA-glycosylase (AUDG) to eliminate the carryover contamination. Thus, label-free MCDA-LFB assay complemented with AUDG enzyme was a rapid, simple, sensitive and reliable technique for detection of target pathogen, which has the ability to effectively avoid carryover contamination, and can be a valuable tool for "on-site" detection, clinical diagnosis, and primary quarantine purposes.