The Biomedical And Analytical Applications Of Near-Infrared-Responsive Nanomaterials With Aptamer-Functionalization

In recent years,near-infrared(NIR)light has been widely used in biomedicine and bioanalysis due to its deep tissue penetration and minimal photodamage to human tissue and organs.Nanomaterials possess distinguishly different optical,electric and magnetic properties compared to their bulk counterparts.NIR-responsive nanomaterials are a special kind of materials that can produce special optical or photothermal effect under the excitation of NIR light,making them promising in applications such as targeted bioimaging and photothermal therapy.Aptamers are short,single-stranded DNA or RNA molecules that can recognize any molecule of interest with high affinity and specificity.The targets of aptamers are ranging from metal ions,small molecules,biological macromolecules,cells to live tissues Compared to antibodies,aptamers possess several advantages,such as design flexibility,tolerant of harsh synthetic conditions,easy modification,and biochemical stability.Therefore,aptamers can potentially endow NIR-responsive nanomaterials with intelligent recognizing capabilities.The application of aptamer functionalized NIR light responsive nanomaterials can thus be extended to various fields,ranging from enzyme activity regulation,targeted and controlled drug release to analysis.It is obvious that NIR light responsive nanomaterials with aptamer functionalization have huge potential in modern biomedicine and bioanalysis and diverse applications.In this paper,a series of NIR-responsive nanomaterials have been synthesized and modified with different aptamers.Their application in biomedicine and bioanalysis were systematically investigated.An enzyme activity regulation system,a targeted and controlled drug release system and a lateral flow immunochromatographic assay system were constructed.The major content of the paper includes three following aspects:(1)A system composed of aptamer-functionalized magnetic beads/gold nanorods nanocomposites was developed for reversible regulation of thrombin activity under NIR light stimulation.By using proximity-dependent surface hybridization assay,a closed-loop structure has been constructed with thrombin and two thrombin-binding aptamers,significantly enhancing the inhibition capabilities of aptamers towards thrombin.Owing to the excellent localized surface plasmon resonances(LSPRs)property,gold nanorods(AuNRs)display good photothermal effect.The activity of inhibited thrombin was efficiently recovered by utilizing AuNRs as photothermal agents to disrupt the closed-loop structure.Thrombin can catalyze the conversion of fibrinogen into fibrin.Thus the activity of thrombin was determined by real-time monitoring the changes of light scattering capability of the reaction solution.Thrombin clotting time measurement in human plasma further illustrated the promise of the regulation method in clinical applications.Furthermore,the artificial dialysis simulation experiments demonstrated this method can also be used in potential areas such as the hemofiltration of renal failure therapy.(2)The core-shell structured upconversion nanoparticles with UV emission were synthesized and encapsulated with a layer of uniform mesoporous silica shells to construct the core-shell structured UCNPs@mSiO2 nanocomposites.When further modified with DNA sequences,the obtained multifunctional nanocomposites.can be performed as NIR photon-manipulated DNA nanomachines for targeted drug delivery.A single-stranded DNA molecule with an extension of aptamer region that can specifically recognize cancer cells was immobilized on the surface of the core-shell nanoparticles.The other complementary azobenzene-modified DNA molecule was hybridized with the aptamer-modified DNA to form double-strand DNA molecule for blocking the pores in the mSiO2.When the UCNPs@mSiO2-aptamer nanocomposites touched cancer cells with the guidance of aptamer,upconversion UCNPs nanoparticles can emit ultraviolet light to stimulate the isomerization of azobenzene under NIR light excitation.The photoisomerization of azobenzene induced the dehybridization of double-strand DNA complementary DNA,leading to the uncapping of the mesoporous pores and the loaded drug was finally released.We anticipate that this NIR-responsive nanocomposite could be used as photocontrolled drug release system in cancer therapy.(3)NaYF4 nanoparticles with green emission were synthesized through the thermal decomposition method.When functionalized with aptamer,the resultant upconversion luminescence probe was obtained and can serve as the signal vehicles in the detection of small organic molecules pesticides with the lateral flow immunochromatographic assay(LFIA).The fluorescent strip was promising to improve the selectivity and sensitivity through eliminating the background fluorescence interference.Moreover,the developed LFIA would provide enormous potential as a useful tool for detection of many analytes such as small molecules and proteins.The technique also allows detection of a variety of substances simultaneously by utilizing upconversion nanoparticles with different emission bands.