Simple and sensitive method for detecting point mutations of epidermal growth factor receptor using cationic conjugated polymers

Current status and new experimental diagnostic methods of invasive fungal infections after hematopoietic stem cell transplantation

Invasive fungal infections (IFIs) are common and life-threatening complications in post-hematopoietic stem cell transplantation (post-HSCT) recipients, Severe IFIs can lead to systemic infection and organ damage, which results in high mortality in HSCT recipients. With the development of the field of fungal infection diagnosis, more and more advanced non-culture diagnostic tools have been developed, such as glip biosensors, metagenomic next-generation sequencing, Magnetic Nanoparticles and Identified Using SERS via AgNPs+ , and artificial intelligence-assisted diagnosis. The advanced diagnostic approaches contribute to the success of HSCT and improve the overall survival of post-HSCT leukemia patients by supporting therapeutical decisions. This review provides an overview of the characteristics of two high-incidence IFIs in post-HSCT recipients and discusses some of the recently developed IFI detection technologies. Additionally, it explores the potential application of cationic conjugated polymer fluorescence resonance energy transfer (CCP-FRET) technology for IFI detection. The aim is to offer insights into selecting appropriate IFI detection methods and gaining an understanding of novel fungal diagnostic approaches in laboratory settings.

Conjugated Polymers-based Luminescent Probes for Ratiometric Detection of Biomolecules

Accurate monitoring of the biomolecular changes in biological and physiological environments is of great significance for pathogenesis, development, diagnosis and treatment of diseases. Compared with traditional luminescent probes on the...

Sensitive monitoring of RNA transcription by optical amplification of cationic conjugated polymers

We reported a new strategy for sensitive monitoring in vitro RNA synthesis in real time based on fluorescence resonance energy transfer (FRET) from water-soluble conjugated polymer poly (9, 9-bis (6'-N, N, N,-trimethylammonium) hexyl) fluorene-co-alt-1,4-phenylene) bromide (PFP) to fluorogenic RNA aptamer/fluorophore (Spanich2/DFHBI and Broccoli/DFHBI) system. In this strategy, RNA of interest was transcribed accompanied by the Spanich2 or Broccoli. Then the 3, 5-difluoro-4-hydroxybenzylidene imidazolinone (DFHBI) bound to the RNA aptamer sequence and thereby induced a fluorescence signal. PFP was used as the fluorescence energy donor, and Spanich2/DFHBI was the fluorescence energy acceptor. The fluorescence signal of Spanich2/DFHBI was amplified by light-harvesting and fluorescence amplification ability of PFP via FRET. And the limit of detection (LOD) (0.29 nM) was near 10-fold lower than that of RNA aptamer/DFHBI (LOD is 2.8 nM) alone by measuring the FRET ratio, which greatly reduced the variation of background signals. Most importantly, the addition of PFP did not interfere with RNA transcription in vitro, so this method was successfully applied to sensitively monitor RNA transcription and effect of T7 RNA polymerase inhibitor in real time, supplying a sensitive and simple method to study the modulation and inhibitor of RNA polymerase in vitro.

Sensitive genotyping of mutations in the EGFR gene from NSCLC patients using PCR-GoldMag lateral flow device

Epidermal growth factor receptor (EGFR) mutations predict better outcomes with EGFR tyrosine kinase inhibitors in patients with non-small cell lung cancer (NSCLC). Most common activating mutations include in-frame deletion in exon 19 and L858R substitution in exon 21, which account for >90% of all EGFR mutations in NSCLC. In this study, a PCR-GoldMag lateral flow assay (PCR-GoldMag LFA) was developed for the visual detection of delE746-A750 and L858R of EGFR mutations. Forty formalin-fixed paraffin-embedded (FFPE) tissue samples of NSCLC patients were analyzed using PCR-GoldMag LFA system and verified by direct sequencing and TaqMan-PCR detection methods. Results showed that EGFR mutations were detected in 34 cases among the 40 samples (85%) by PCR-GoldMag LFA method. Among the 34 cases, 5 cases were simultaneously detected with delE746-A750 in exon 19 and L858R mutation in exon 21. Compared with sequencing, only 4 samples were detected as delE746-A750, which revealed higher sensitivity of PCR-GoldMag LFA detection method than direct sequencing. TaqMan-PCR method verified the L858R mutation and was in 100% agreement with our method. These results indicated that our method has obvious advantages to analyze clinical samples and offers a more sensitive alternative to direct sequencing for the detection of EGFR mutations.

Effect of Zinc oxide nanoparticle on Fluorescence Resonance Energy transfer between Fluorescein and Rhodamine 6G

Fluorescence Resonance Energy Transfer between two dyes Fluorescein and Rhodamine 6G were investigated in solution in the presence and absence of Zinc oxide nanoparticle. Zinc oxide nanostructure is used as the fluorescence enhancing agent for the present study since donor (Fluorescein) fluorescence increase significantly in presence of nanoparticle. Accordingly, the energy transfer efficiency in the presence of nanoparticle increases. The maximum efficiency was 69% for acceptor (Rhodamine 6G) concentration of 0.75×10^-5M. The energy transfer efficiency was found to be pH sensitive and it varies from 4.15% to 90.00% in mixed dye solution for a change in pH from 1.5 to 10.0. With proper calibration it is possible to use the present system under investigation to sense pH which is better with respect to our previous reported results [Spectrochim. Acta Part A. 149 (2015) 143-149] as it can sense a wide range of pH and with better sensitivity.

Fluorescence Visual Detection of Herbal Product Substitutions at Terminal Herbal Markets by CCP-based FRET technique

Inaccurate labeling of materials used in herbal products may compromise the therapeutic efficacy and may pose a threat to medicinal safety. In this paper, a rapid (within 3 h), sensitive and visual colorimetric method for identifying substitutions in terminal market products was developed using cationic conjugated polymer-based fluorescence resonance energy transfer (CCP-based FRET). Chinese medicinal materials with similar morphology and chemical composition were clearly distinguished by the single-nucleotide polymorphism (SNP) genotyping method. Assays using CCP-based FRET technology showed a high frequency of adulterants in Lu-Rong (52.83%) and Chuan-Bei-Mu (67.8%) decoction pieces, and patented Chinese drugs (71.4%, 5/7) containing Chuan-Bei-Mu ingredients were detected in the terminal herbal market. In comparison with DNA sequencing, this protocol simplifies procedures by eliminating the cumbersome workups and sophisticated instruments, and only a trace amount of DNA is required. The CCP-based method is particularly attractive because it can detect adulterants in admixture samples with high sensitivity. Therefore, the CCP-based detection system shows great potential for routine terminal market checks and drug safety controls.

Recent Advances in Conjugated Polymer Materials for Disease Diagnosis

The extraordinary optical amplification and light-harvesting properties of conjugated polymers impart sensing systems with higher sensitivity, which meets the primary demands of early cancer diagnosis. Recent advances in the detection of DNA methylation and mutation with polyfluorene derivatives based fluorescence resonance energy transfer (FRET) as a means to modulate fluorescent responses attest to the great promise of conjugated polymers as powerful tools for the clinical diagnosis of diseases. To facilitate the ever-changing needs of diagnosis, the development of detection approaches and FRET signal analysis are highlighted in this review. Due to their exceptional brightness, excellent photostability, and low or absent toxicity, conjugated polymers are verified as superior materials for in-vivo imaging, and provide feasibility for future clinical molecular-imaging applications. The integration of conjugated polymers with clinical research has shown profound effects on diagnosis for the early detection of disease-related biomarkers, as well as in-vivo imaging, which leads to a multidisciplinary scientific field with perspectives in both basic research and application issues.

Homogeneous fluorescent specific PCR for the authentication of medicinal snakes using cationic conjugated polymers

A label-free, homogenous and sensitive one-step method for the molecular authentication of medicinal snakes has been developed by combining a rapid PCR technique with water-soluble cationic conjugated polyelectrolytes (CCPs). Three medicinal snake materials (Deinagkistrodon acutus, Zaocys dhumnades and Bungarus multicinctus; a total of 35 specimens) and 48 snake specimens with similar morphologies and textures were clearly distinguished by the naked eye by utilizing a CCP-based assay in a high-throughput manner. The identification of medicinal snakes in patented Chinese drugs was successfully performed using this detection system. In contrast to previous fluorescence-labeled oligonucleotide detection and direct DNA stain hybridization assays, this method does not require designing dye-labeled primers, and unfavorable dimer fluorescence is avoided in this homogenous method.

Targeted therapies for patients with advanced NSCLC harboring wild-type EGFR: what's new and what's enough

Historically, non-small cell lung cancer (NSCLC) is divided into squamous and nonsquamous subtypes based on histologic features. With a growing number of oncogenic drivers being identified in squamous and nonsquamous NSCLC, this malignancy has been recently divided into several distinct subtypes according to the specific molecular alterations. This new paradigm has substantially highlighted the treatment of advanced NSCLC, shifting it from standard chemotherapy according to specific histologic subtypes to targeted therapy according to specific oncogenic drivers. The application of epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) in NSCLC patients harboring activating EGFR mutations has been a representative model of precise medicine in the treatment of NSCLC. As the role of EGFR-TKIs in routine management of patients with advanced NSCLC has been well established, this review provides an overview of alternative targeted therapy in the treatment of NSCLC, including EGFR-TKIs for patients with wild-type EGFR NSCLC, as well as other targeted agents either clinical available or in early- to late-stage development.

Nonenriched PCR Versus Mutant-Enriched PCR in Detecting Selected Epidermal Growth Factor Receptor Gene Mutations Among Nonsmall-Cell Lung Cancer Patients

BACKGROUND

Biopsies obtained from lung cancers contain a mixture of cancerous and healthy tissues. The mutant-enriched polymerase chain reaction (ME-PCR) identifies low-level somatic DNA mutations within an excess wild-type sample.

AIMS

This study aimed at comparing nonenriched PCR (NE-PCR) versus ME-PCR for the detection of two epidermal growth factor receptor (EGFR) gene mutations among nonsmall cell lung cancer patients.

METHODS

Fifty lung tissue biopsies were screened for inframe TTAA deletions in exon-19 and the L858R point mutation in exon-21, using ME-PCR and NE-PCR, followed by capillary electrophoresis.

RESULTS

Only exon-19 deletions were detected in 22% and 18% of cases using ME-PCR and NE-PCR, respectively. Diagnostic performance of the NE-PCR versus the ME-PCR serving as a "gold standard" revealed a sensitivity of 82%, and a specificity of 100%, with positive and negative predictive values of 100% and 95%, respectively, and an overall accuracy of 96%. Despite a strong agreement shown between the two assays (K=0.875), the NE-PCR showed an 18% false-negative rate in bronchoscopically obtained biopsies compared to ME-PCR.

CONCLUSION

The false negativity encountered with NE-PCR in bronchoscopically obtained samples makes ME-PCR the technique of choice in such situations.

[Immunohistochemical detections of EGFR status in NSCLC]

背景与目的

存在表皮生长因子受体（epidermal growth factor receptor, EGFR）突变的非小细胞肺癌（non-small cell lung cancer, NSCLC）患者对EGFR酪氨酸激酶抑制剂（tyrosine kinase inhibitor, TKI）治疗有良好反应。与检测EGFR突变的分子水平手段相比，免疫组织化学法（immunohistochemistry, IHC）价格低廉，操作简便、迅速，易开展。本研究旨在探索免疫组化法检测EGFR突变的准确性。

方法

选取97例NSCLC患者的手术或组织活检标本行EGFR特异性抗体的免疫组化染色，分析染色阳性标本的临床病理特征，并继续接受液相芯片检测验证是否存在突变；新收集40例被证实为EGFR突变的手术标本接受免疫组化染色，计算免疫组化法检出突变灵敏度。

结果

97例NSCLC标本，17例染色阳性，染色阳性标本好发于女性、腺癌、不吸烟患者中，其染色阳性标本中，76.9%实际存在突变。40例EGFR突变标本中，免疫组化法检出突变的灵敏度为40%。

结论

免疫组化法染色评分为强阳性的标本结果准确，但该方法灵敏度不甚理想，不同研究者所得结果差异较大，临床推广是否可行仍有待进一步探讨。

Investigation of Fluorescence Resonance Energy Transfer between Fluorescein and Rhodamine 6G

Fluorescence Resonance Energy Transfer between two organic dyes Fluorescein and Rhodamine 6G was investigated in aqueous solution in presence and absence of synthetic clay laponite. Spectroscopic studies suggest that both the dyes were present mainly as monomer in solution. Fluorescence Resonance Energy Transfer occurred from Fluorescein to Rhodamine 6G in solutions. Energy transfer efficiency increases in presence of laponite and the maximum efficiency was 72.00% in aqueous laponite dispersion. Energy transfer efficiency was found to be pH sensitive. It has been demonstrated that with proper calibration it is possible to use the present system under investigation to sense pH over a wide range from 1.5 to 8.0.

A single quantum dot-based biosensor for DNA point mutation assay

We develop a single quantum dot-based biosensor for sensitive and selective detection of DNA point mutation.

Real time in vitro regulation of DNA methylation using a 5-fluorouracil conjugated DNA-based stimuli-responsive platform

DNA methylation, catalyzed by methylases, plays a critical role in many biological processes, and many methylases have been regarded as promising targets for antimicrobial drugs. In this work, we report a stimulus responsive, self-regulating anticancer drug release platform, comprising a multifunctional DNA that upon methylation by methyltransferase (MTase) releases 5-fluorouracil (5-Fu) and in turn inhibits subsequent expression of MTase. The multifunctional DNA with anticancer drug are first methylated by DNA adenine methylation (DAM) methyltransferase (MTase) and then cut by the methylation-sensitive restriction endonuclease Dpn I. Removal of duplex from the functional DNA by the methylation/cleavage process will release the anticancer drug, resulting in inhibition of the activity of DAM in turn. Consequently, the enzyme activity of DAM MTase can be self-regulated. Furthermore, we found that the inhibition efficiency of 5-Fu significantly increase as it is functionalized with DNA.

Polymer nanoparticle-protein interface. Evaluation of the contribution of positively charged functional groups to protein affinity

Cationic-functionalized polymer nanoparticles (NPs) show strikingly distinct affinities to proteins depending on the nature of the cationic functional group. N-Isopropylacrylamide (NIPAm) polymer NPs incorporating three types of positively charged functional groups (guanidinium, primary amino, and quaternary ammonium groups) were prepared by precipitation polymerization. The affinities to fibrinogen, a protein with an isoelectric point (pI) of 5.5, were compared using UV-vis spectrometry and a quartz crystal microbalance (QCM). Guanidinium-containing NPs showed the highest affinity to fibrinogen. The observation is attributed to strong, specific interactions with carboxylate groups on the protein surface. The affinity of the positively charged NPs to proteins with a range of pIs revealed that protein-NP affinity is due to a combination of ionic, hydrogen bonding, and hydrophobic interactions. Protein affinity can be modulated by varying the composition of these functional monomers in the acrylamide NPs. Engineered NPs containing the guanidinium group with hydrophobic and hydrogen bonding functional groups were used in an affinity precipitation for the selective separation of fibrinogen from a plasma protein mixture. Circular dichroism (CD) revealed that the protein was not denatured in the process of binding or release.

EGFR mutation testing in lung cancer: a review of available methods and their use for analysis of tumour tissue and cytology samples

Aims

Activating mutations in the gene encoding epidermal growth factor receptor (EGFR) can confer sensitivity to EGFR tyrosine kinase inhibitors such as gefitinib in patients with advanced non-small-cell lung cancer. Testing for mutations in EGFR is therefore an important step in the treatment-decision pathway. We reviewed reported methods for EGFR mutation testing in patients with lung cancer, initially focusing on studies involving standard tumour tissue samples. We also evaluated data on the use of cytology samples in order to determine their suitability for EGFR mutation analysis.

Methods

We searched the MEDLINE database for studies reporting on EGFR mutation testing methods in patients with lung cancer.

Results

Various methods have been investigated as potential alternatives to the historical standard for EGFR mutation testing, direct DNA sequencing. Many of these are targeted methods that specifically detect the most common EGFR mutations. The development of targeted mutation testing methods and commercially available test kits has enabled sensitive, rapid and robust analysis of clinical samples. The use of screening methods, subsequent to sample micro dissection, has also ensured that identification of more rare, uncommon mutations is now feasible. Cytology samples including fine needle aspirate and pleural effusion can be used successfully to determine EGFR mutation status provided that sensitive testing methods are employed.

Conclusions

Several different testing methods offer a more sensitive alternative to direct sequencing for the detection of common EGFR mutations. Evidence published to date suggests cytology samples are viable alternatives for mutation testing when tumour tissue samples are not available.