Inkjet Samples Research Articles

Abstract LB-314: Development of reference material guaranteed copy number of DNA for liquid biopsy

Abstract cfDNA (cell free DNA) analysis using liquid biopsy plays an important role in cancer research. In particular NGS (next-generation sequencer)-based assay has attracted wide interests, because it can not only screen many cancer genes but also can detect ultra-low-concentration mutations at the same time. However, there is no reference material to evaluate correctly its performance. Currently, most researchers use diluted human genomic DNA that is commercially available as reference, but adjusting its concentration is difficult because of the Poisson distribution. Herein, we have developed a method to dispense cells with counting a cell one by one using inkjet technology (Manabu Seo, et. Al., 2019, Anal. Chem.). By lysing cells after dispensing, the defined copy number of DNA is prepared with a single molecule level. In this study, we assessed the feasibility of our reference material prepared by inkjet as a control for rare mutation detection (e.g. minimal sampling bias and high reproducibility). Spike-in control samples with exact allele frequencies with 0.07%, 0.53%, 0.64%, and 1.0%, were prepared by accurately dispensing with inkjet the cells that contain a sequence of exons 18, 19, 20, and 21 of EGFR. The EGFR sequence has G719A, E746_A750del, T790M, C797S, L858R, and L861Q mutations. For comparison, a few samples were also prepared by manual dilution process. The EGFR mutations were analyzed by the method of high-sensitivity procedure using NGS (Yoji Kukita, et. Al., 2013, PLoS ONE.). Result of the inkjet method had less variation than the manual dilution method, and high repeatability was obtained. Especially in E746_A750del (0.53%) the inkjet samples were tested three times (n = 24 each), and their CVs (coefficient of variation) were 17%, 17%, and 12%. In contrast, the manual sample's one was 33%. In addition, linearity of T790M and L858R were R2 = 0.98 and R2 = 0.96, respectively. The reference material produced by inkjet method can be provided under the same conditions at each facility and make it possible to improve the reliability of liquid biopsy. Therefore, the reference material could be appropriate standard for external quality control for EGFR mutant detection of liquid biopsy. Citation Format: Yusuke Osaki, Yoshiharu Sato, Miho Ishii, Yuki Yonekawa, Ryo Matoba. Development of reference material guaranteed copy number of DNA for liquid biopsy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr LB-314.

Forensic analysis of printing inks using tandem Laser Induced Breakdown Spectroscopy and Laser Ablation Inductively Coupled Plasma Mass Spectrometry

Elemental analysis, using either LA-ICP-MS or LIBS, can be used for the chemical characterization of materials of forensic interest to discriminate between source materials originating from different sources and also for the association of materials known to originate from the same source. In this study, a tandem LIBS/LA-ICP-MS system that combines the benefits of both LIBS and LA-ICP-MS was evaluated for the characterization of samples of printing inks (toners, inkjets, intaglio and offset.). The performance of both laser sampling methods is presented. A subset of 9 black laser toners, 10 colored (CMYK) inkjet samples, 12 colored (CMYK) offset samples and 12 intaglio inks originating from different manufacturing sources were analyzed to evaluate the discrimination capability of the tandem method. These samples were selected because they presented a very similar elemental profile by LA-ICP-MS. Although typical discrimination between different ink sources is found to be >99% for a variety of inks when only LA-ICP-MS was used for the analysis, additional discrimination was achieved by combining the elemental results from the LIBS analysis to the LA-ICP-MS analysis in the tandem technique, enhancing the overall discrimination capability of the individual laser ablation methods. The LIBS measurements of the Ca, Fe, K and Si signals, in particular, improved the discrimination for this specific set of different ink samples previously shown to exhibit very similar LA-ICP-MS elemental profiles. The combination of these two techniques in a single setup resulted in better discrimination of the printing inks with two distinct fingerprint spectra, providing information from atomic/ionic emissions and isotopic composition (m/z) for each ink sample.

Ink jet printing of bio-treated linen, polyester fabrics and their blend

Cellulosic fabrics were surface modified using Brewer's yeast filtrate and cellulase enzymes (Valumax A828, Valumax A356) to enhance its affinity to ink jet printing. The effect of enzymes on the surface structure and morphology of the cellulosic fabrics used has been illustrated using scanning electron microscope. Related test as tensile strength have been measured. The bio-treated cellulosic fabrics were digitally printed and the colour strength (K/S) and % increase in K/S were measured. Effect of different conditions (enzyme concentration, temperature and time) was investigated to obtain the optimum condition of each enzyme for each fabric that or which was indicated by higher colour strength. Results show a noticeable increase in the K/S especially for cellulosic linen and its blend compared to the standard samples. The optimum conditions to obtain the higher K/S by using Brewer's yeast filtrate and the other two cellulase enzymes in the pre-treatment of ink jet samples were obtained.

Characterization of toners and inkjets by laser ablation spectrochemical methods and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy

Detection and sourcing of counterfeit currency, examination of counterfeit security documents and determination of authenticity of medical records are examples of common forensic document investigations. In these cases, the physical and chemical composition of the ink entries can provide important information for the assessment of the authenticity of the document or for making inferences about common source. Previous results reported by our group have demonstrated that elemental analysis, using either Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) or Laser Ablation Induced Breakdown Spectroscopy (LIBS), provides an effective, practical and robust technique for the discrimination of document substrates and writing inks with minimal damage to the document. In this study, laser-based methods and Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS) methods were developed, optimized and validated for the forensic analysis of more complex inks such as toners and inkjets, to determine if their elemental composition can differentiate documents printed from different sources and to associate documents that originated from the same printing source. Comparison of the performance of each of these methods is presented, including the analytical figures of merit, discrimination capability and error rates. Different calibration strategies resulting in semi-quantitative and qualitative analysis, comparison methods (match criteria) and data analysis and interpretation tools were also developed. A total of 27 black laser toners originating from different manufacturing sources and/or batches were examined to evaluate the discrimination capability of each method. The results suggest that SEM-EDS offers relatively poor discrimination capability for this set (~70.7% discrimination of all the possible comparison pairs or a 29.3% type II error rate). Nonetheless, SEM-EDS can still be used as a complementary method of analysis since it has the advantage of being non-destructive to the sample in addition to providing imaging capabilities to further characterize toner samples by their particle morphology. Laser sampling methods resulted in an improvement of the discrimination between different sources with LIBS producing 89% discrimination and LA-ICP-MS resulting in 100% discrimination. In addition, a set of 21 black inkjet samples was examined by each method. The results show that SEM-EDS is not appropriate for inkjet examinations since their elemental composition is typically below the detection capabilities with only sulfur detected in this set, providing only 47.4% discrimination between possible comparison pairs. Laser sampling methods were shown to provide discrimination greater than 94% for this same inkjet set with false exclusion and false inclusion rates lower than 4.1% and 5.7%, for LA-ICP-MS and LIBS respectively. Overall these results confirmed the utility of the examination of printed documents by laser-based micro-spectrochemical methods. SEM-EDS analysis of toners produced a limited utility for discrimination within sources but was not an effective tool for inkjet ink discrimination. Both LA-ICP-MS and LIBS can be used in forensic laboratories to chemically characterize inks on documents and to complement the information obtained by conventional methods and enhance their evidential value.

Effect of Input Precision on Line Micro Quality Measurement

Line quality micro-measurement is of important content of objective measurement, contributing to reproduction quality assessment of digital printed character and line metrics. Transforming physical presswork to digital image is not only the first but also a key procedure in micro quality measurement. In this study, effect of input resolution was verified in order to determine the precision requirement in micro quality survey. A series of experiments were carried out to measure same inkjet samples, which were scanned with a normal flatbed in three resolution sets. The effect on assessment accuracy of resolution condition was analyzed by pair-wise comparison method. Results show that normal flatbed is precise enough for micro line quality measurement. But 600DPI identified in ISO13660 standard is too low to serve in this survey. 1200DPI can work well enough and extra-high resolution version will not respond to improve the measurement precision obviously in inkjet line attribute evaluation.

Test Target Design Considerations for Automated Image Quality Analysis of Samples Subject to Distortion

Measuring image quality automatically requires that feature locations be known and predictable. This predictability is necessary for successful application of both large field of view, low magnification image analysis (such as mottle) and small field of view, high magnification image analysis (such as line and dot quality) in a machine-vision based system. Variations in sample placement and in the registration of images on the samples produce systematic errors in absolute feature locations that require compensation.Compensation for systematic image placement errors is straightforward. Macroscopic image or sample placement variations can be corrected automatically by using a large field of view camera and an image offset calculation. However, even after the macroscopic image placement correction has taken place, microscopic position variations can still exist. These variations can wreak havoc with high magnification measurements that rely on specific region of interest placement on specific features within the field of view. In some cases, dynamic location can be used for small adjustments within the field of view of the high magnification camera. This combination of macro and micro adjustment works well for most samples where absolute or relative feature positions are known.Difficulties arise when positional variations of features are not systematic or rectilinear. Certain types of samples are susceptible to local or global deformation, which can change the relative position of features. For example, cockled paper, or ink jet samples with highly saturated areas are prone to local deformations, while textiles exhibit major topological variations as well as global deformations that result in non-rectilinear distortions caused by the fabric weave. Although topological variations in samples printed on paper and other paper-like substrates can be largely compensated for through the use of a strong vacuum to hold a sample flat, there are residual, non-systematic positional changes of features that can interfere with traditional automated measurement techniques.This paper will present a series of specific test target design considerations and testing methods that can be used to enable automated image quality measurement of distorted image samples.