graphene sheets have become a versatile platform for the fabrication of innovative hybrid materials with various functions due to their unique electrical, optical, thermal, and mechanical properties. The preparation of graphene-based composites with nanoscale precision is highly important for reproducible and controllable performance through the analysis of interplay between each component. In particular, the layer-by-layer (LbL) assembly technique is known as a simple, inexpensive, and versatile process for the fabrication of highly ordered multilayer film structures from various types of materials. The LbL structures capable of controlling nanoscale composition and architectures are achieved through the sequential adsorption of oppositely charged components by attractive forces such as electrostatic interactions. In this review, we will focus on the recent progress in graphene-based nanocomposites hybridized with various nanomaterials such as carbon nanomaterials, polymers, and inorganic nanoparticles by the LbL assembly. Multilayered graphene nanocomposites exhibit improved physical/chemical properties and superior performance compared with the individual components due to the synergistic effects in various applications including electric devices, energy storage and conversion, and biological usages.

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An innovative nucleus-targeting zwitterionic carbon dot (CD) vehicle has been developed for anticancer drug delivery and optical monitoring. The zwitterionic functional groups of the CDs introduced by a simple one-step synthesis using β-alanine as a passivating and zwitterionic ligand allow cytoplasmic uptake and subsequent nuclear translocation of the CDs. Moreover, multicolor fluorescence improves the accuracy of the CDs as an optical code. The CD-based drug delivery system constructed by non-covalent grafting of doxorubicin, exhibits superior antitumor efficacy owing to enhanced nuclear delivery in vitro and tumor accumulation in vivo, resulting in highly effective tumor growth inhibition. Since the zwitterionic CDs are highly biocompatible and effectively translocated into the nucleus, it provides a compelling solution to a multifunctional nanoparticle for substantially enhanced nuclear uptake of drugs and optical monitoring of translocation.

A universal colorimetric method for the detection of nucleic acids, based on ionic interactions by polydiacetylene (PDA) liposomes, is described. Primary and quaternary amine‐modified diacetylene monomers were synthesized and used to generate positively charged PDA liposomes. The resulting PDA sensors showed a dramatic color change from blue to red upon the addition of nucleic acids amplified by using the polymerase chain reaction (PCR) due to the stimuli caused by ionic interactions between the positively charged PDA and negatively charged phosphate backbone of the nucleic acids. The color change that takes place can be simply detected by the naked eye. Compared with quaternary amine‐functionalized PDA vesicles, the primary amine‐functionalized PDA underwent a more intense color transition under optimized conditions. By using the PDA‐based colorimetric sensor, nucleic acids amplified by common PCR reaction, whose typical concentration is around 100 nM, can be readily detected. Since implementation of this universal colorimetric method is simple, rapid and does not require any sophisticated instrumentation, it should have greatly enhanced applications as a technology for DNA diagnosis.

The development of a bidentate aptamer-functionalized polydiacetylene (PDA) liposome sensor that is capable of specifi c colorimetric detection of proteins, directly in complex mixtures (e.g., serum), at sub-micromolar concentrations within 15 min, is reported. In comparison to sensors fabricated with a single aptamer reagent, the conjugation of bidentate aptamer pairs that recognize two distinct exosites of the target protein (thrombin) to the liposome results in signifi cant enhancements of the sensitivity and the specifi city. To elucidate the mechanism behind this enhancement, experimental evidence is presented that suggests that the liposomic aggregation triggered by specifi c, multi-site binding to the target protein is responsible for the improved colorimetric response. Since the colorimetric protein sensor does not require any power or instrumentation, it offers a promising approach towards molecular diagnostics at point-of-care (POC), especially in low-resource settings.