Pattern Biosensing,Bioimaging And Photothermal Generation Of H₂S Molecules Based On Optical Nanomaterials

In recent years,with the rapid development of nanotechnology,a series of optical nanomaterials with unique physical and chemical properties have been developed.Among them,quantum dots?QDs?,gold nanoparticles?AuNPs?and graphene have been widely used in fluorescent detection,optical imaging and medical therapy,due to their excellent optical properties,facile preparation and high biocompatibility.Meanwhile,gas molecular therapy emerged as a new approach for disease treatment,however,it is still in its infancy and there are still many key scientific problems to be solved,such as the stimuli-response,controlled release,and specific targeting.Therefore,in this paper,several optical biosensing and bioimaging strategies were developed based on the excellent optical properties of QDs,AuNPs and graphene.Meanwhile,the pyrolysis of dithiocarbamatefor generation of H₂S and gas molecular therapy was also preliminary investigated.The detailed description is listed as follows:1.Protein-driven disassembly of surfactant-polyelectrolyte nanomicelles:modulation of quantum dot/fluorochrome fluorescence resonance energy transfer?FRET?for pattern sensingSeven different kinds of FRET systems were constructed with different surfactants and polymer coated FRET pair,and it was used for the discrimination of five different human serum proteins through tar get-triggered disassembly of the noncovalent amphiphilic surfactant-polyelectrolyte nanomicelle.Firstly,four different surfactants and four poly electrolytes were utilized to fabricate seven noncovalent amphiphilic polymer nanomicelles through supramolecular electrostatic assemblies.The apolar interiors of nano micelle had sequestered QDs/Texasred-DHPE fluorochrome as FRET donor-acceptor pair.The extent of nano micelles disassembly,induced by five different human serum proteins?immunoglobulin,human serum albumin,?-antitrypsin,fibrinogen,transferrin?,led to fluorescence attenuation of the fluorochrome and gave distinct fluorescence response patterns.These patterns could be quantitatively differentiated by linear discriminate analysis.The sensor array was successfully used to identify five human serum proteins.The transmission electron microscope and dynamic light scattering results confirmed the assembly and disassembly of the complex structure and FRET based signal difference.This pattern sensing method is simple,fast and high throughput.Furthermore,an unknown concentration of proteins was also effectively distinguished through absorption normalization algorithm.This study demonstrated the utility of the supramolecular disassemble to modulate the FRET process and present a flexible pattern sensing platform for rapid identify and discrimination of biological proteins.2.Quantum dot/methylene blue FRET mediated near-infrared?NIR?fluorescent nanomicelles with large Stokes shift for bioimagingA new kind of large Stokes shifting fluorescent nanoprobe for NIR bio imaging was developed by packing the highly efficient FRET complex between the QDs donor and the methylene blue?MB?acceptor in the cetyltrimethylammonium bromide?CTAB?nanomicelles.The hydrophobic CdSe/ZnS QDs?605 nm?and MB were loaded in the nano mice lles via the formation of microemulsion.The nano micelle was about 6.8 nm with high colloidal stability and photostability.Its size changed little at 20 ?,40 ? and 60 ?,and its fluorescence at 609 nm changed little under five hours of UV irradiation.The FRET efficiency reached up to 82.2%.The highly efficient FRET between the QDs and MB extended the Stokes shift to 202 nm and significantly enhanced the signal to noise ratio in the cellular and in vivo imaging.Therefore,the FRET nanomicelles with large Stokes shift could be potentially employed as an ideal fluorescence contrast agent for in vivo NIR imaging.3.Biomime tic synthesis of highly biocompatible gold nanoparticles with amino acid-dithiocarbamate as a precursor for surface-enhanced raman scattering?SERS?imagingA series of amino acid functionalized gold nanoparticles was synthesized based on the pyrolysis of the amino acid-dithiocarbamate?amino acid-DTC?and used for the SERS imaging of cell.Glycine?Gly?,glutamic acid?Glu?,and histidine?His?were chosen as representative amino acid candidates to synthesize corresponding amino acid-DTC compounds.The pyrogenic decomposition of amino acid-DTC initiated the reduction synthesis of AuNPs,and the strong coordinating dithiocarbamate group of amino acid-DTC served as stabilizer that grafted on the surface of AuNPs,which rendered the as-prepared nanoparticles negative surface charge and high colloidal stability.Meanwhile,the bio mimetic AuNPs showed strong SERS effect with an enhancement factor of 9.8×105 for Rhodamine 6G,and two distinct Raman peaks located at 1363 and 1509 cm^-1 could be obviously observed in cell imaging experiments.Therefore,the biomimetic AuNPs can be explored as excellent SERS contrast nanoprobe for biomedical imaging,and the amino acid-DTC mediated synthesis of AuNPs has a great potential in bio-engineering and biomedical imaging applications.4.Photothermal generation of H₂S based on dithiocarbamate/Au@Au-Ag NPs encapsulated polumer microspheresA remote light controlled H₂S generation system was constructed via doping Au@Au-Ag photothermal nanoparticles and the H₂S donor Gly-DTC together in a polymer microspheres.The system was used for the modulation of intracellular H₂S level.First,the glycine dithiocarbamate?Gly-DTC?and the Au@Au-Ag nanoparticles were doped in polymer microspheres?Gly-DTC/Au@Au-Ag nanoparticles microspheres?with diameter of 13.6 ± 3.5 ?m through synchronous assembly.Upon 780 nm laser irradiation,the encapsulated Au@Au-Ag nanoparticles can effectively convert NIR laser into heat,that lead to the thermolysis of Gly-DTG,and generation of H₂S molecules.The results indicated that the H₂S generation was mainly triggered by NIR light in the presence of photothemal nanoparticle and the H₂S donor.The amount of H₂S generated could reach up to 68.1 ?M.We further examined the culture of the microspheres with CEM cells.It was found that H₂S generation form microspheres can efficiently diffuse to CEM cells.Therefore,this work provided a new remote,controllable,non-invasive and real-time approach for the generation of H₂S.5.Photothermal generation of H₂S based on dithio carba mate/re duce d graphene oxide?RGO?nanocomposite for intracellular reactive oxygen species?ROS?scavengingPo lye thy le n imine der ivate d dit hio c arbamate?PEI-DTC?encapsulated RGO nano materials were constructed for the efficient photothermal generation of H₂S molecules,which was utilized for the scavenging of the intracellular ROS and the oxidation of H₂O₂.The PEI-DTC was firstly adsorbed on the surface of the RGO based on the electrostatic interaction to form PEI-DTC/RGO nanocomposites.Upon NIR laser irradiation,the PEI-DTC/RGO nanocomposite can effectively convert NIR laser into heat,that lead to the thermolysis of Gly-DTC,and generation of H₂S molecules.The amount of released H₂S could reach up to 66.7 ?M.We further examined the response of cell to the photothermal generated H₂S molecules.It was found that the intracellular H₂S concentration increased due to the H₂S generation from the PEI-DTC/RGO nanocomposite.At the same time,both the level of ROS and Caspase 3 dereased,the expression of Caspase 3 dropped down to 24.8%.These results confirmed that the PEI-DTC/RGO nanocomposite under NIR irradiation exhibited potent cellular protection against oxidative injury?H₂O₂?.This work provided a simple and flexible approach for fabricating H₂S donor polymer and a new way to clear the intracellular ROS and H₂O₂.It will provide a reference for celluar antioxidant research and has potential application in the field of gas molecular therapy.