Highly sensitive nanozyme strip:An effective tool for forensic material evidence identification

During criminal case investigations,blood evidence tracing is critical for criminal investigation.However,the blood stains are often cleaned or covered up after the crime,resulting in trace residue and difficult tracking.Therefore,a highly sensitive and specific method for the rapid detection of human blood stains remains urgent.To solve this problem,we established a nanozyme-based strip for rapid detection of blood evidence with high sensitivity and specificity.To construct reliable nanozyme strips,we synthesized CoFe_(2)O_(4) nanozymes with high peroxidase-like activity by scaling up to gram level,which can be supplied for six million tests,and conjugated antibody as a detection probe in nanozyme strip.The developed CoFe_(2)O_(4) nanozyme strip can detect human hemoglobin(HGB)at a concentration as low as 1 ng/mL,which is 100 times lower than the commercially available colloidal gold strips(100 ng/mL).Moreover,this CoFe_(2)O_(4) nanozyme strip showed high generality on 12 substrates and high specificity to human HGB among 13 animal blood samples.Finally,we applied the developed CoFe_(2)O_(4) nanozyme strip to successfully detect blood stains in three real cases,where the current commercial colloidal gold strip failed to do.The results suggest that the CoFe_(2)O_(4) nanozyme strip can be used as an effective on-scene detection method for human blood stains,and can further be used as a long-term preserved material evidence for traceability inquiry.

Biochemistry of mammalian ferritins in the regulation of cellular iron homeostasis and oxidative responses

Ferritin,an iron-storage protein,regulates cellular iron metabolism and oxidative stress.The ferritin structure is characterized as a spherical cage,inside which large amounts of iron are deposited in a safe,compact and bioavailable form.All ferritins readily catalyze Fe(II)oxidation by peroxides at the ferroxidase center to prevent free Fe(II)from participating in oxygen free radical formation via Fenton chemistry.Thus,ferritin is generally recognized as a cytoprotective stratagem against intracellular oxidative damage.The expression of cytosolic ferritins is usually regulated by iron status and oxidative stress at both the transcriptional and post-transcriptional levels.The mechanism of ferritin-mediated iron recycling is far from clarified,though nuclear receptor co-activator 4(NCOA4)was recently identified as a cargo receptor for ferritin-based lysosomal degradation.Cytosolic ferritins are heteropolymers assembled by H-and L-chains in different proportions.The mitochondrial ferritins are homopolymers and distributed in restricted tissues.They play protective roles in mitochondria where heme-and Fe/S-enzymes are synthesized and high levels of ROS are produced.Genetic ferritin disorders are mainly related to the L-chain mutations,which generally cause severe movement diseases.This review is focused on the biochemistry and function of mammalian intracellular ferritin as the major iron-storage and anti-oxidation protein.