Modulating the Morphology of Gold Graphitic Nanocapsules for Plasmon Resonance-Enhanced Multimodal Imaging.

With their unique optical properties and distinct Raman signatures, graphitic nanomaterials can serve as substrates for surface-enhanced Raman spectroscopy (SERS) or provide signal amplification for bioanalysis and detection. However, a relatively weak Raman signal has limited further biomedical applications. This has been addressed by encapsulating gold nanorods (AuNRs) in a thin graphitic shell to form gold graphitic nanocapsules. This step improves plasmon resonance, which enhances Raman intensity, and has the potential for integrating two-photon luminescence (TPL) imaging capability. However, changing the morphology of gold graphitic nanocapsules such that high quality and stability are achieved remains a challenge. To address this task, we herein report a confinement chemical vapor deposition (CVD) method to prepare the construction of AuNR-encapsulated graphitic nanocapsules with these properties. Specifically, through morphological modulation, we (1) achieved higher plasmon resonance with near-IR incident light, thus achieving greater Raman intensity, and (2) successfully integrated two-photon luminescence dual-modal (Raman/TPL) bioimaging capabilities. Cancer-cell-specific aptamers were further modified on the AuNR@G graphitic surface through simple, but strong, π-π interactions to achieve imaging selectivity through differential cancer cell recognition.

Simultaneous tracking of drug molecules and carriers using aptamer-functionalized fluorescent superstable gold nanorod-carbon nanocapsules during thermo-chemotherapy.

Controlling and monitoring the drug delivery process is critical to its intended therapeutic function. Many nanocarrier systems for drug delivery have been successfully developed. However, biocompatibility, stability, and simultaneously tracing drugs and nanocarriers present significant limitations. Herein, we have fabricated a multifunctional nanocomposite by coating the gold nanorod (AuNR) with a biocompatible, superstable and fluorescent carbon layer, obtaining the AuNR@carbon core-shell nanocapsule. In this system, the carbon shell, originally obtained in aqueous glucose solutions and, therefore, biocompatible in physiological environments, could be simply loaded with cell-specific aptamers and therapeutic molecules through π-π interactions, a useful tool for cancer-targeted cellular imaging and therapy. Moreover, such a stable and intrinsic fluorescence effect of the AuNR@carbon enabled simultaneous tracking of released therapeutic molecules and nanocarriers under thermo-chemotherapy. The AuNR@carbons had high surface areas and stable shells, as well as unique optical and photothermal properties, making them promising nanostructures for biomedical applications.

Alkyne-functionalized superstable graphitic silver nanoparticles for Raman imaging.

Noble metals, especially gold, have been widely used in plasmon resonance applications. Although silver has a larger optical cross section and lower cost than gold, it has attracted much less attention because of its easy corrosion, thereby degrading plasmonic signals and limiting its applications. To circumvent this problem, we report the facile synthesis of superstable AgCu@graphene (ACG) nanoparticles (NPs). The growth of several layers of graphene onto the surface of AgCu alloy NPs effectively protects the Ag surface from contamination, even in the presence of hydrogen peroxide, hydrogen sulfide, and nitric acid. The ACG NPs have been utilized to enhance the unique Raman signals from the graphitic shell, making ACG an ideal candidate for cell labeling, rapid Raman imaging, and SERS detection. ACG is further functionalized with alkyne-polyethylene glycol, which has strong Raman vibrations in the Raman-silent region of the cell, leading to more accurate colocalization inside cells. In sum, this work provides a simple approach to fabricate corrosion-resistant, water-soluble, and graphene-protected AgCu NPs having a strong surface plasmon resonance effect suitable for sensing and imaging.

[Study on pan-resistant Klebsiella pneumoniae harboring blaKPC-2 type carbapenemase gene from a hospital outbreak in Huzhou, Zhejiang].

OBJECTIVE: To investigate the status of genotype of the KPC (Klebsiella pneumoniae carbapenemase)-encoding genes in Pan-resistant K. Pneumoniae, isolated from the 98th Hospital of People's Liberation Army, Huzhou district, Zhejiang province, China. METHODS: 19 strains of Pan-resistant K. pneumoniae were isolated from the inpatients between November, 2008 and July, 2009. Phenotypic confirmatory test for suspected carbapenemases production were carried out by Modified Hodge test. Carbapenemase gene of bla(KPC) was analyzed by PCR and verified by DNA sequencing. RESULTS: In 19 strains of K. pneumoniae, the positive rates of Modified Hodge test and gene of bla(KPC) were both 100.0%. These genes all belonged to bla(KPC-2) subtype confirmed by nucleotide sequence analysis. Among them, the bla(KPC-2) gene sequence of the HZ001 strain (its original serial number was HZ9871) had been registered in GenBank (GenBank Accession Number: GU086225). CONCLUSION: All of the Pan-resistant K. pneumoniae isolated from the inpatients harbored bla(KPC-2) type carbapenemases gene and causing an outbreak in a hospital. Carbapenemases that producing type KPC-2 might be the major reason which causing the resistance to Carbapenems antibiotics.

[Emergence of 16S rRNA methylase gene rmtB in Klebsiella pneumoniae isolates from the inpatients in Zhejiang Province, China].

OBJECTIVE: To investigate the presence and genetic background of 16S rRNA methylase gene and Aminoglycoside modifying enzymes (AMEs) genes in Klebsiella pneumoniae isolated from the People's Liberation Army 98th Hospital, Huzhou district, Zhejiang province, China. METHODS: 25 strains of Klebsiella pneumoniae were isolated from the inpatients between September, 2005 and April, 2006. 6 kinds of 16S rRNA methylase gene (including armA, rmtA, rmtB, rmtC, rmtD and npmA), 6 kinds of AMEs genes [including aac (3)-I, aac (3)-II, aac (6')-I, aac (6')-II, ant (3")-I and ant (2")-I], intI1, intI2, intI3, mercuric reductase gene merA (merA gene were the collective genetic markers of transposons of Tn21 and Tn501) and tnpA (tnpA gene were the collective genetic markers of transposons of Tn1, Tn2,Tn3 and Tn1000) were analyzed by PCR and verificated by DNA sequencing. RESULTS: In 25 strains of Klebsiella pneumoniae, the positive rate of genes of rmtB, aac (3)-II, aac (6')-I, ant (3")-I and intI1 were 60.0% (15/25), 4.0% (1/25), 48.0% (12/25), 60.0% (15/25) and 96.0% (24/25), respectively. The rest 12 kinds of genes were all tested negative. The total positive rate of 6 kinds of AMEs gene was 84.0% (21/25). CONCLUSION: There were very high positive rate on both genes of rmtB and AMEs genotypes in Klebsiella pneumoniae isolated from inpatients, and this was the first report of the emergence of 16S rRNA methylase gene rmtB in Klebsiella pneumoniae identified in Zhejiang province, China.