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Bioinert gold nanoparticles of various shapes and functionalities are widely accepted as contrast agents (CAs) for several modalities of imaging, viz., electron microscopy, computerized tomography (CT), X-ray and photoacoustic (PA) imaging. However, testing of novel compact-imaging probes for ocular diagnostic imaging is always challenging. Here, ultra-fast microwave oven synthesized gold nanocages (AuNcgs) were successfully demonstrated for high-contrast PA ocular imaging for the first time. Methods are described for the synthesis, characterization and application of quickly synthesized AuNcgs in diagnostic ocular imaging. PA and ultrasound (US) images were acquired using a commercial US imaging scanner integrated with a tunable nanosecond pulsed laser. This integrated hybrid-modality system is a combined PA and US platform for imaging which enabled acquiring of complementary structural and optical absorption-based information simultaneously. Initial experiments were conducted using tubings filled with solutions of different concentrations of quickly synthesized AuNcgs. Biological PA and US imagings were demonstrated using enucleated porcine eye samples. Based on the acquired results, it is envisaged that AuNcgs can be employed as a high strength PA CA to potentially diagnose ocular disease like uveal melanoma in the near future. MOE (Min. of Education, S’pore) Accepted version

Gold nanocages (AuNcgs) are well-studied, hollow, metallic nanostructures that have fascinated researchers in the fields of nanotechnology, materials science, photoelectronics, biotechnology, and medical science for the last decade. However, the time-consuming synthesis of AuNcgs has limited their widespread use in materials science and nano-biotechnology. A novel, ultra-fast, simple, and highly convenient method for the production of AuNcgs using microwave heating is demonstrated herein. This quick method of AuNcg synthesis requires mild laboratory conditions for large-scale production of AuNcgs. The microwave heating technique offers the advantage of precise mechanical control over the temperature and heating power, even for the shortest reaction period (i.e., seconds). Microwave-synthesized AuNcgs were compared with conventionally synthesized AuNcgs. Structural maneuver studies employing the conventionally produced AuNcgs revealed the formation of screw dislocations and a shift in the lattice plane. Detailed characterization of the microwave-generated AuNcgs was performed using high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and spectroscopic techniques.

Highly conductive biocompatible graphene is synthesized using ecofriendly reduction of graphene oxide (GO). Two strains of non-pathogenic extremophilic bacteria are used for reducing GO under both aerobic and anaerobic conditions. Degree of reduction and quality of bacterially reduced graphene oxide (BRGO) are monitored using UV–vis spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. Structural morphology and variation in thickness are characterized using electron microscopy and atomic force microscopy, respectively. Electrical measurements by three-probe method reveal that the conductivity has increased by 104–105 fold from GO to BRGO. Biocompatibility assay using mouse fibroblast cell line shows that BRGO is non-cytotoxic and has a tendency to support as well as enhance the cell growth under laboratory conditions. Hereby, a cost effective, non-toxic bulk reduction of GO to biocompatible graphene for green electronics and bioscience application is achieved using halophilic extremophiles for the first time.

A multifunctional nanoparticle based on carboxymethyl cellulose was developed. Folate group was attached to nanoparticle for specific recognition of cancerous cells and 5FU was encapsulated for delivering cytotoxicity. The whole system was able to track by the semiconductor quantum dots that were attached to the nanoparticle. The multifunctional nanoparticle was characterized by UV-VIS spectra, PL spectra, FTIR, TEM, SEM etc and was targeted to human breast cancer cell, MCF7. The biocompatibility of nanoparticle without drug and cytotoxicity rendered by nanoparticle with drug was studied with MCF7 and L929 cell lines. The epifluorescent images suggest that the folate-conjugated nanoparticles were more internalized by folate receptor positive cell line, MCF7 than the noncancerous L929 cells.

Sulfated polysaccharides are complex polysaccharide molecules with excellent physico-chemical properties and bioactivities. On the basis of origin, they are classified as plant, animal, microbial and chemically synthesized sulfated polysaccharides. They have been widely applied in the fields of material and biological sciences. Biocompatibility and biodegradability of these molecules facilitate their increased use in the nanoparticle synthesis and tissue engineering applications. This review focuses on the structure, function and applications of important types of natural and chemically derived sulfated polysaccharides in the fields of nanotechnology and biomedical sciences. In the first part, we discuss the classification and role of sulfated polysaccharides in various fields. Later, we elaborate the specific bionano applications of commercially important sulfated polysaccharides in ionic gelation, stabilizing, cross-linking, capping and encapsulation of drugs. Finally, we conclude with the future scope and advanced applications of sulfated polysaccharides in various fields of interdisciplinary science. From the Clinical Editor This comprehensive review focuses on the structure, function, and applications of natural and chemically derived sulfated polysaccharides in the fields of nanotechnology and biomedical sciences.

Precise control of the placement and patterning of graphene on various substrates has tremendous impact in many fields, such as nanoscale electronics, multifunctional optoelectronic devices, and molecular sensing. A one-step facile technique involving N2-plasma promotes surface modification and enhances the surface wettability of the substrate. The technique is employed to create partially hydrophilic surfaces on SiO2/Si substrate with the aid of various templates, enabling the selective deposition, alignment, and formation of patterns comprising monolayer graphene oxide (GO) sheets; it successfully uses the Langmuir–Blodgett (LB) deposition technique over a large area without the need of any sophisticated equipment. Various characterization techniques are carried out in order to understand the possible mechanism behind the pinning of the GO on the partially treated areas. It is a relatively easy and swift process that can reliably accomplish specific surface modification with high bonding strength between GO and the substrate. This technique allows the creation of patterns with controllable dimensions. For example, the thickness of the GO sheets can be controlled; this is particularly important in creating arrays and devices at wafer-scale. Being simple yet effective and inexpensive, this technique holds tremendous potential that can be exploited for numerous applications in the field of bio-nanoelectronics.