Photoluminescence Mechanisms of Dual-Emission Fluorescent Silver Nanoclusters Fabricated by Human Hemoglobin Template: From Oxidation- and Aggregation-Induced Emission Enhancement to Targeted Drug Delivery and Cell Imaging

Abstract

A novel fundamental understanding of the features of mechanism for the synthesis of luminescent silver nanoclusters (AgNCs) in human hemoglobin (Hb) as capping/reducing agents is presented based upon simultaneous size transition and fluorescence enhancement phenomena The interesting features consist of both NC core oxidation and aggregation-induced emission (AIE) attributed to ligand-to-metal charge transfer (LMCT) or ligand-to-metal–metal charge transfer (LMMCT) from Ag­(I)-Hb complexes (through oxygen, nitrogen, and sulfur atoms of Hb residues donation to the Ag­(I) ions) forming Ag(0)@Ag­(I)–Hb core–shell NCs, the origin and consequence being a dual emission/single excitation nanosystem with large stocks shift and high quantum yield obtained even at high temperature which is a challenging subject, is not reported until now. The bioconjugation of hyaluronic acid (HA) onto surfaces of an Hb layer (HA/AgNCs) produced a biocompatible platform with a doxorubicin drug (DOX) as DOX/HA/AgNCs for specific imaging and delivery of DOX via an efficient targeting of CD44-overexpressing cancer cells, which lead to an increased inhibition of tumor cell growth. Additionally, the cell viability analysis illustrated that the developed nanocarriers significantly enhanced the DOX uptake in HeLa cancer cells compared to HUVEC and HNCF-PI 52 normal cells allowing a selective cytotoxicity to HeLa cells. The suggested LMCT/LMMCT mechanism for an emission source combined with such attractive properties as a simple one-pot, nontoxic, synthesis route, long lifetime, large Stocks shift, excellent aqueous stability and photostability, and easy functionalization capability with good cell viability provided the possibility for a AgNCs nanoprobe for use to better understand the nucleation and growth mechanisms via computational modeling techniques (e.g., DFT study) and also for fabrication of new nanoprobes for developing multifunctional applications in the biobased chemical and electrochemical fields and in in vivo research.

Shape-Controlled Synthesis of Luminescent Hemoglobin Capped Hollow Porous Platinum Nanoclusters and their Application to Catalytic Oxygen Reduction and Cancer Imaging

“…Thus, the solution contains two species, a blue emitting cluster, and a red emitting Hb/Pt NCs system, when Pt NCs were synthesized with a low concentration of H 2 PtCl 6 (0.125 mM). Since the PL band at 760 nm probably arises from the surface state 26 – 29 , the emission at 450 nm is much higher than that of 760 nm. This finding could be due to a low fraction of Pt (II) species on the cluster surface (~13.68%) as discussed below in XPS spectra, which is similar to the emission spectra of Ag NCs 26 and in contrast to the emission spectra of Cu NCs in the previous reports 29 , 30 .…”

“…1d ). Moreover, compared to Au NCs, prepared under the same conditions 25 , Hb/Pt NCs exhibited near-infrared (NIR) fluorescence emission at λ em = 760 nm (λ ex = 320 nm) attributed to a larger cluster size 14 , 26 . The emission intensity at 760 and 450 nm reaches a maximum after about 22 days (Fig.…”

Strategies for the Development of Metallic‐Nanoparticle‐Based Label‐Free Biosensors and Their Biomedical Applications

“…Thiol atoms present in TCh bind with Ag NCs (AgÀS) and enhancet he fluorescence intensity of DNA-templated Ag NCs by LMCT or LMMCT (charget ransfer from the sulfur atom in the thiolate ligand to silver NCs). [67][68][69] The addition of TCh from 0t o2 0nm increased the fluorescence of dC 12 -Ag NCs by increasingt he number of AgÀSb onds. The LOD was 0.3 nm.O ther enzymes, except AChE, displayed nearly no change in fluorescencei ntensity; thus verifyingi ts specificity.T he activity of AChE with dC12-Ag NCs waschecked in the human red blood cell (RBC) membrane through the Ellmanm ethod, which was used to detect the activity of AChE by measuring thiol groups.B oth experiments displayed similar results;t hus affirming the sensitivity and specificity of this mechanism.…”

“…The mechanism involves the hydrolysis of acetylthiocholine (ATCh) by AChE and release of TCh. Thiol atoms present in TCh bind with Ag NCs (Ag−S) and enhance the fluorescence intensity of DNA‐templated Ag NCs by LMCT or LMMCT (charge transfer from the sulfur atom in the thiolate ligand to silver NCs) . The addition of TCh from 0 to 20 n m increased the fluorescence of dC 12 ‐Ag NCs by increasing the number of Ag−S bonds.…”

Quantification of controlled release leuprolide and triptorelin in rabbit plasma using electromembrane extraction coupled with HPLC–UV

“…It has been demonstrated that castration levels can be achieved with continuous administration of LA or TA . In recent years, drug delivery systems have been developed significantly in order to deliver pharmaceutical compounds in a controlled manner and in a more efficient way that results in desired biological effects and proper treatment . Depot formulation based on biodegradable polymers is one of the novel drug delivery systems, which has been developed in order to deliver LA or TA in a controlled manner within a particular period of time (over 1–6 months, depending on the formulation).…”