3D-printing for forensic chemistry: voltammetric determination of cocaine on additively manufactured graphene-polylactic acid electrodes.

Cocaine is probably one of the most trafficked illicit drugs in the world. For this reason, police forces require fast, selective, and sensitive methods for cocaine detection at crime scenes. Taking benefit of additive manufacturing, we demonstrate that 3D-printed graphene-polylactic acid (G-PLA) electrodes using the affordable fused deposition modelling technique can identify and quantify cocaine in seized drugs. The detection of cocaine based on its electrochemical oxidation on such electrodes was dramatically improved after an electrochemical surface treatment that generates reduced graphene oxide (anodic followed by a cathodic treatment). Square-wave voltammetric determination of cocaine was achieved in the concentration range between 20 and 100 µmol L-1, with a detection limit of 6 µmol L-1, and free from the interference of paracetamol, caffeine, phenacetin, lidocaine, benzocaine and levamisole, which are common adulterants found in seized drugs. The analytical characteristics obtained using 3D-printed G-PLA electrodes were comparable with those of previously reported electrochemical sensors, but presented the inherent advantages of the 3D-printing technology that enables low-cost, reproducible, and large-scale production of such electrodes in remote areas combined with the use of an environmentally-friendly biopolymer.

KRAS mutation status is highly homogeneous between areas of the primary tumor and the corresponding metastasis of colorectal adenocarcinomas: one less problem in patient care.

Background: Mutations in KRAS are negative predictors of the response to anti-EGFR therapies in the treatment of metastatic colorectal cancer. Yet, the ideal tissue to test for KRAS mutation-primary or metastatic-remains unknown, as is the validity of testing only 1 area of the primary tumor. The aim of this study was to determine the heterogeneity of KRAS mutational status between areas of the primary lesion and between paired primary CRC and the corresponding lymph node (LN), liver, and lung metastasis with a high-sensitivity sequencing method. Design: DNA from 2 or 3 areas from the primary tumor and 1 area of metastatic tissue was obtained from formalin-fixed paraffin-embedded specimens from 102 metastatic CRC patients. Mutations in KRAS codons 12, 13, and 61 were analyzed by pyrosequencing. RESULTS: Ninety-one cases had DNA extracted from more than 1 area of the primary tumor. Only 1 patient showed intratumor heterogeneity, which involved KRAS mutation type, not KRAS mutational status. We examined KRAS mutations in 97 primaries and matched metastatic samples, recording 2 discordant cases, representing 2.1% of our cohort of matched samples. Conclusion:KRAS status is highly homogeneous throughout primary CRC tumor areas and consistent between the primary tumor and metastatic tissue in the same patient. Our data suggest that testing KRAS mutations in only 1 area of the primary or metastatic tissue is suitable for predicting the response to anti-EGFR treatment and guiding clinical decisions.