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Hydrogen, oxygen, carbon, and nitrogen isotopes derived from three different strains of silkworms at different life stages involved in silkworm rearing, were measured to understand the fractionation characteristics of stable isotopes at different stages of silkworm development, and to trace the movement of these isotopes from food to larva to excrement and finally to silk. We found that silkworm strain had little effect on δ2H, δ18O and δ13C values. However, a large difference was found in the δ15N levels of newly-hatched silkworms between Jingsong Haoyue and Hua Kang No. 3 orthogonal strains, suggesting that the mating and egg laying differences may result in an inconsistent kinetic nitrogen isotope fractionation. The δ13C values of silkworm pupae and silkworm cocoon also displayed significant differences, suggesting that heavy carbon isotopes are greatly fractionated from the larva to the silk during cocoon formation. Overall, these results may be used to clarify the relationship between isotope fractionation and the ecological process of the Bombyx mori and expand our ability to resolve stable isotope anomalies at a small regional-scale level. [ABSTRACT FROM AUTHOR]

We report the preparation of a specific fibroin antibody and its use for the identification of unearthed ancient silk relics. Based on the 12-amino-acid repeat sequence 'GAGAGSGAGAGS', which is found in fibroin of the silkworm Bombyx mori, a specific antibody against fibroin was prepared in rabbits through peptide synthesis and carrier-protein coupling. This antibody was highly specific for fibroin found in silk. Using this antibody we have successfully identified four silk samples from different time periods. Our results reveal, for the first time, a method capable of detecting silk from a few milligrams of archaeological fabric that has been buried for thousands of years, confirming that the ancient practice of wearing silk products while praying for rebirth dated back to at least 400 BCE. This method also complements current approaches in silk detection, especially for the characterization of poorly preserved silks, promoting the investigation of silk origins and of ancient clothing cultures. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The origin and dissemination of silk have been hotly debated in the field of archaeology, and the key to resolving this controversy lies in the detection and species identification of ancient silk microtraces. Herein, a taxonomically specific anti-fibroin monoclonal antibody was successfully prepared and a layer-by-layer self assembly electrochemical immunosensor was innovatively proposed for detecting silk traces based on flexible carbon cloth. The immunosensor possessed a broad linear range of 10−2-103 ng mL−1 and a detection limit of 2.15 pg mL−1 for the ultrasensitive detection of Bombyx mori silk traces. In addition, the elaborate immunosensor exhibited satisfactory high specificity, storage stability and reproducibility. In particular, the qualitative and quantitative performance of the immunosensor was excellent in the analysis of archaeological samples. Therefore, this work demonstrates that the proposed method not only provides a reliable analytical tool for exploring the origin and spread of archaeological silk, but also improves our understanding of how to use emerging materials like two-dimensional titanium carbide to creat innovative biosensors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultrasensitive detection is critical for investigating silk's origin and spread. • A dual-responsive PEC immunosensor was prepared for silk microtrace detection. • The sensor was developed by in-situ growth of Ag 2 S on ZnO-MXene nanocomposites. • The sensor exhibits excellent taxonomic specificity, repeatability and stability. • The dual-responsive PEC immunosensor is applied for detection of real silk samples. Developing an effective analytical method for microtrace detection of ancient silk is highly desirable and vitally crucial for exploring the origin and spread of silk. Herein, a taxonomically specific anti-fibroin monoclonal antibody was prepared and an elaborate visible/near-infrared (vis/NIR) photoelectrochemical (PEC) immunosensor was proposed. The sensor employed Ag 2 S nanoparticles (NPs) grown in situ on ZnO nanowire array-MXene nanocomposites (ZnO-MX) via a sonochemical method as a photosensitive material. The experimental results illustrated that the ZnO-MX/Ag 2 S-based sensor presented 6.8 times larger PEC responses than a ZnO-MX-based sensor under visible light illumination, and the PEC signal of the ZnO-MX/Ag 2 S nanocomposites was 30 times as high as that of ZnO-MX under 808 nm NIR light, indicating enhanced photoelectric activity and a matched energy band structure of ZnO with MXene and Ag 2 S. This PEC immunosensor exhibited excellent potential for the ultrasensitive detection of Bombyx mori silk traces due to its wide linear range of 0.005–50 ng mL−1 and low detection limit of 1.51 pg mL−1. Additionally, the immunosensor showed outstanding specificity, stability, and repeatability, particularly for the qualitative detection of archeological artifacts. Given its aforementioned benefits, ZnO-MX/Ag 2 S nanocomposites are potentially attractive photoactive materials for use in vis/NIR PEC immunosensors. Moreover, this demonstrated method offers a feasible method to investigate the history and distribution of ancient silk. [ABSTRACT FROM AUTHOR]

Achieving efficient identification of silk protein requires highly sensitive analytical techniques and favorable extraction methods, which is of great significance to the research of ancient silk, especially for the controversial issue of the silk origin. In this paper, proteomics and western blot were proposed to analyze the silk proteins of Bombyx mori (B. mori) and Antheraea pernyi (A. pernyi) dissolved by different methods. First, the differences in secondary structure were detected via spectroscopy. LC-MS/MS was then employed to characterize the peptides of silk proteins precisely. LiBr solution exhibited outstanding dissolution effect on B. mori cocoon, with 87 proteins detected; while copper-ethylenediamine solution (CED) was more appropriate for A. pernyi cocoon, and 16 proteins were identified in A. pernyi -CED. In addition to fibroin and sericin, abundant seroins, enzymes, protease inhibitors, other functional proteins and uncharacterized proteins were detected. Based on the LC-MS/MS data, diagnostic antibodies for the two species were prepared, and fibroin was successfully identified by western blot assay because both dissolution methods were gentle and did not destroy the antigenic epitopes in the protein molecule. Owing to their good specificity and high sensitivity, these diagnostic antibodies have good application prospects in immunoassays of different silk species. This study presents the comprehensive analysis on silk identification of proteins from B. mori and A. pernyi extracted by different methods via the proteomic and immunology as well as the conventional approaches. Great coverage of two cocoon proteomes was accomplished, which demonstrated the outstanding difference in components and abundance. Based on the proteomics analysis, the diagnostic antibodies against two species were prepared and identified the corresponding fibroin successfully in the completed protein mixtures. To our knowledge, the proteomic and immunology procedures with high efficiency, sensitivity and specificity are novel analysis on the silk identification and has great potential in the field of ancient silk detection. Unlabelled Image • The secondary structure of silk proteins obtained by different methods were well characterized. • The iBAQ proteomic analysis indicates differences in silk proteins of Bombyx mori (B. mori) and Antheraea pernyi (A. pernyi). • Highly sensitive polyclonal antibodies were prepared successfully to silk proteins of B. mori and A. pernyi , respectively. [ABSTRACT FROM AUTHOR]