Synthesis of nanomaterials with multi-imaging modality is of great importance in clinical molecular imaging and diagnostics. This work reports novel synthetic strategy to create ultrasmall and hexagonal upconversion nanoparticles (UCNPs), -NaGdF 4 : Yb 3+ , Er 3+ , and -NaGdF 4 : Yb 3+ , Tm 3+ , with inherent magnetic and efficient upconversion properties. The use of new combination of lanthanide chloride and sodium TFA as the precursors for UCNPs gave the best results in terms of size (10-40 nm), crystallinity and morphology, and proved to be cost-and time-saving. Water solubilization of both NaGdF 4 : Yb 3+ , Er 3+ , and -NaGdF 4 : Yb 3+ , Tm 3+ UCNPs was achieved by homogeneous polymer coating using amphiphilic poly(acrylic acid) derivatives. The strong upconversion and magnetic properties were maintained after extensive polymer coating process. To see the potential of the UCNPs for biological applications, the surface of NaGdF 4 : Yb 3+ , Er 3+ UCNPs were functionalized with Ni-nitrilotriacetate (NiNTA) moiety. The remarkable specificity of these NiNTAUCNPs for the oligohistidine peptide was clearly shown by both magnetic resonance and optical imaging. Finally, the cellular uptake of these UCNPs was investigated by fluorescence microscope using spectral imaging technique.

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Understanding the underlying mechanisms involved in graphene growth via chemical vapour deposition (CVD) is critical for precise control of the characteristics of graphene. Despite much effort, the actual processes behind graphene synthesis still remain to be elucidated in a large number of aspects. Herein, we report the evolution of graphene properties during in-plane growth of graphene from reduced graphene oxide (RGO) on copper (Cu) via methane CVD. While graphene is laterally grown from RGO flakes on Cu foils up to a few hundred nanometres during CVD process, it shows appreciable improvement in structural quality. The monotonous enhancement of the structural quality of the graphene with increasing length of the graphene growth from RGO suggests that seeded CVD growth of graphene from RGO on Cu surface is accompanied by the restoration of graphitic structure. The finding provides insight into graphene growth and defect reconstruction useful for the production of tailored carbon nanostructures with required properties.The growth of graphene on copper (Cu) substrates via chemical vapour deposition (CVD) 1,2 has been extensively exploited for the purpose of achieving large-area, high-quality single crystals, which are highly desirable for the practical use of graphene in industrial applications [3][4][5][6] . Together with their technological appeal, such systems also serve as a unique platform for broadening our fundamental understanding of a new and intriguing class of growth phenomena. In particular, the overall properties of CVD-grown graphene films are sensitively dependent on diverse parameters 7-12 including purity of copper, types of carbon precursors, temperature, and vapour pressure. However, the wide variation in properties of CVD-grown graphene films under similar growth conditions suggests that fine-tuning of the growth parameters is still required. Thus, the actual processes and the underlying mechanisms involved in graphene growth 7-15 are vital to understand for achieving precise control of the graphene growth.CVD growth of graphene on Cu is a surface-mediated process 14 . During the CVD process, nucleation of graphene critical nuclei occurs spontaneously and randomly on the Cu surface, and then monolayer graphene is subsequently synthesized from the edge of the graphene nuclei [13][14][15][16] . Recently, monolayer graphene has been also grown from seeds intentionally patterned or prepared on Cu prior to the CVD process [16][17][18][19] , instead of from graphene seeds spontaneously and randomly nucleated on Cu during the CVD process. Specifically, CVD-grown graphene monolayer or multilayer grains 17,18 and mechanically exfoliated graphene or graphite flakes 17,18 have been utilized as seeds for obtaining high-quality monolayer graphene. In addition, poly(methyl methacrylate) (PMMA) dots 19 and chemically derived graphene oxide (GO) flakes