title: Cysteine-capped ZnSe quantum dots as affinity and accelerating probes for microwave enzymatic digestion of proteins via direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis.
abstract: Fluorescent semiconductor quantum dots (QDs) exhibit great potential and capability for many biological and biochemical applications. We report a simple strategy for the synthesis of aqueous stable ZnSe QDs by using cysteine as the capping agent (ZnSe-Cys QDs). The ZnSe QDs can act as affinity probes to enrich peptides and proteins via direct matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) analysis. This nanoprobe could significantly enhance protein signals (insulin, ubiquitin, cytochrome c, myoglobin and lysozyme) in MALDI-TOFMS by 2.5-12 times compared with the traditional method. Additionally, the ZnSe-Cys QDs can be applied as heat absorbers (as accelerating probes) to speed up microwave-assisted enzymatic digestion reactions and also as affinity probes to enrich lysozyme-digested products in MALDI-TOFMS. Furthermore, after the enrichment experiments, the solutions of ZnSe-Cys QDs mixed with proteins can be directly deposited onto the MALDI plates for rapid analysis. This approach shows a simple, rapid, efficient and straightforward method for direct analysis of proteins or peptides by MALDI-TOFMS without the requirement for further time-consuming separation processes, tedious washing steps or laborious purification procedures. The present study has demonstrated that ZnSe-Cys QDs are reliable and potential materials for rapid, selective separation and enrichment of proteins as well as accelerating probes for microwave-digested reactions for proteins than the regular MALDI-MS tools. Additionally, we also believe that this work may also inspire investigations for applications of QDs in the field of MALDI-MS for proteomics.
authors: Department of Chemistry, National Sun Yat-Sen University, Kaohsiung 80424, Taiwan.
authors: Lokesh A
authors: LA
authors: Shastri
authors: Suresh Kumar
authors: SK
authors: Kailasa
authors: Hui-Fen
authors: HF
authors: Wu
mesh_terms: D003545:Cysteine / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D045304:Cytochromes c / Q000032:analysis; D007328:Insulin / Q000032:analysis; D008872:Microwaves; D009113:Muramidase / Q000032:analysis / Q000378:metabolism; D010455:Peptides / Q000032:analysis / Q000378:metabolism; D011506:Proteins / Q000032:analysis* / Q000378:metabolism*; D045663:Quantum Dots; D018036:Selenium Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000191:economics / Q000379:methods*; D013997:Time Factors; D014357:Trypsin / Q000378:metabolism; D017967:Zinc Compounds / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism
chemical_list: D007328:Insulin; D010455:Peptides; D011506:Proteins; D018036:Selenium Compounds; D017967:Zinc Compounds; D045304:Cytochromes c; D009113:Muramidase; D014357:Trypsin; D003545:Cysteine; C044696:zinc selenide