Purelab flex system

Ganoderma lucidum spore (GLS, batch No. 14072201), sporoderm-broken Ganoderma lucidum spore (BGLS, batch No. 15121401) and sporoderm-removed Ganoderma lucidum spore (RGLS, batch No. 16042301) were provided by Zhejiang Shouxiangu Institute of Rare Medicine Plant (Zhejiang, China) and the species origin of the samples were authenticated as Ganoderma lucidum (Curtis) P. Karst. by Prof. Mingyan Li in the institute. The samples were kept in the sample room in Pharmaceutical Informatics Institute of Zhejiang University. Vinorelbine (batch No. 140501) was purchased from Jiangsu Haosen Pharmaceutical Co., Ltd (Jiangsu, China). Reference standards including ganoderic acid A, B, C₂, D, DM, F, G, H, ganoderenic acid A, B, C, D, lucidenic acid A were purchased from Nature Standard (Shanghai, China).
HPLC-grade acetonitrile and methanol were purchased from Merck (Darmstadt, Germany). Formic acid (HPLC grade) was purchased from Roe Scientific (Newark, DE, USA). Ethanol and Methylcellulose were acquired from Shanghai Aladdin Bio-Chem Technology (Shanghai, China). Neutral red was purchased from Sigma Aldrich (Saint-Louis, MO, USA). Isopropyl alcohol was purchased from Hangzhou Changzheng Chemical Reagent (Hangzhou, China). Deionized water was prepared with an Elga PURELAB flex system (ELGA LabWater, UK).

d-(+)-Glucose (≥99.5%), phosphate-buffered
saline (PBS) tablets, silver nitrate (≥99.0%), gold(III) chloride
trihydrate (≥99.9%), sodium citrate dihydrate (≥99.0%), l-ascorbic acid (≥99.0%), potassium chloride (≥99.0%),
sulfuric acid (98%), methanol (≥99.9%), polyethylenimine (PEI,
MW ≈ 25000 by LS), Nafion solution (5 wt %), and 4-aminothiophenol
(4-ATP, 97%) were purchased from Sigma-Aldrich. Heme-containing, membrane-bound
bacterial glucose dehydrogenase (GDH) from Ewingella
americana was purified and characterized according
to a previously published protocol.^{39 (link),45 (link)} All aqueous
solutions were prepared in ultrapure water (resistivity of 18.2 MΩ
cm) purified by a Purelab Flex system (ELGA LabWater, High Wycombe,
UK). For whole blood analysis, blood samples from healthy donors were
collected in VACUETTE FC Mix tubes (Greiner Bio-One, Kremsmünster,
Austria). The tubes contain a mixture of additives Na₂EDTA,
sodium fluoride, citric acid, and sodium citrate, which inhibits glycolysis
and prevents coagulation. Blood collection for analysis with the biosensors
was approved by the Swedish Ethical Board (approval number 2009/180).

Ultrapure water was prepared using the Purelab flex system (ELGA LabWater, Wycombe, UK) and all solvents used were of HPLC grade. Certified analytical standards of biflavonoids, including amentoflavone (CAS 1617-53-4), bilobetin (CAS 521-32-4), ginkgetin (CAS 481-46-9), isoginkgetin (CAS 548-19-6), and sciadopitysin (CAS 521-34-6), were purchased from Phytolab (Vestenbergsgreuth, Germany). Plants of Ginkgo biloba L. were collected in Koprivnica, Croatia, in late October 2022. Leaves, seeds and bark samples were collected and then separated to obtain different tissues (Figure 4). Fresh material was quickly frozen and freeze-dried using a laboratory freeze dryer (LIO-5PLT, KAMBIČ, Ljubljana, Slovenia). The dry plant material was pulverized using a bead mill (Bead Ruptor 12, Omni International, USA), sealed under vacuum and stored at room temperature for further experiments.