Single-cell biomagnifier for optical nanoscopes and nanotweezers

Optical microscopes and optical tweezers,which were invented to image and manipulate microscale objects,have revolutionized cellular and molecular biology.However,the optical resolution is hampered by the diffraction limit;thus,optical microscopes and optical tweezers cannot be directly used to image and manipulate nano-objects.The emerging plasmonic/photonic nanoscopes and nanotweezers can achieve nanometer resolution,but the high-index material structures will easily cause mechanical and photothermal damage to biospecimens.Here,we demonstrate subdiffraction-limit imaging and manipulation of nano-objects by a noninvasive device that was constructed by trapping a cell on a fiber tip.The trapped cell,acting as a biomagnifier,could magnify nanostructures with a resolution of 100 nm(λ/5.5)under white-light microscopy.The focus of the biomagnifier formed a nano-optical trap that allowed precise manipulation of an individual nanoparticle with a radius of 50 nm.This biomagnifier provides a high-precision tool for optical imaging,sensing,and assembly of bionanomaterials.

Removal of copper by modified chitosan adsorptive membrane

In this study,a novel adsorptive membrane was prepared from chitosan as the functional polymer and some additive blend solutions by solution casting method.The modified chitosan membrane was characterized by FTIR and its Water Swelling Ratio(WSR).The adsorption of copper ions on the adsorptive membrane was investi-gated in batch experiments.The results obtained from the experiments indicated that the membrane had a good adsorption capacity for copper ions,the optimal ionic strength and pH were 0.1 and 5–6,respectively.Compared with the Langmuir isotherm model,the experimental data were found to be following the Freundlich model.

Lipid droplets as endogenous intracellular microlenses

Using a single biological element as a photonic component with well-defined features has become a new intriguing paradigm in biophotonics.Here we show that endogenous lipid droplets in the mature adipose cells can behave as fully biocompatible microlenses to strengthen the ability of microscopic imaging as well as detecting intra-and extracellular signals.By the assistance of biolenses made of the lipid droplets,enhanced fluorescence imaging of cytoskeleton,lysosomes,and adenoviruses has been achieved.At the same time,we demonstrated that the required excitation power can be reduced by up to 73%.The lipidic microlenses are finely manipulated by optical tweezers in order to address targets and perform their real-time imaging inside the cells.An efficient detecting of fluorescence signal of cancer cells in extracellular fluid was accomplished due to the focusing effect of incident light by the lipid droplets.The lipid droplets acting as endogenous intracellular microlenses open the intriguing route for a multifunctional biocompatible optics tool for biosensing,endoscopic imaging,and single-cell diagnosis.

Optical trapping and orientation of Escherichia coli cells using two tapered fiber probes

We report on the optical trapping and orientation of Escherichia coli(E.coli) cells using two tapered fiber probes.With a laser beam at 980 nm wavelength launched into probe I, an E. coli chain consisting of three cells was formed at the tip of probe I. After launching a beam at 980 nm into probe II, the E.coli at the end of the chain was trapped and oriented via the optical torques yielded by two probes. The orientation of the E. coli was controlled by adjusting the laser power of probe II. Experimental results were interpreted by theoretical analysis and numericalsimulations.