Bovine Serum Albumin-stabilized Gold Nanoclusters Research Articles

Biotin-Modified PEGylated Protein-Stabilized gold Nanoclusters: A strategy for selective and efficient intracellular transport of glucose oxidase for glucose detection

Although bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs) have various applications in biological environments., limited research has been carried out on their potential for intracellular delivery of enzymes and highly selective intracellular detection of specific analytes. We developed biotin-capped polyethylene glycol (PEG)-functionalized bovine serum albumin-stabilized gold nanoclusters (biotin-AuNCs) for enhanced optical properties and bioimaging applications. Biotin-AuNCs exhibited superior performance to BSA-AuNCs, with higher quantum yield (∼14 %), improved photostability, and enhanced resistance to trypsin digestion. These nanoclusters enabled selective imaging of biotin receptor-positive cells such as HeLa and MCF-7, while forming nanocomposites (GOx-AuNCs) with avidin-glucose oxidase (GOx) for intracellular glucose detection. The GOx-AuNCs showed selective imaging capabilities and facilitated glucose sensing through GOx-catalyzed H2O2 production, leading to fluorescence quenching of the biotin-AuNCs. This method provided a reliable indicator for intracellular glucose levels, establishing a linear calibration curve between GOx-AuNC-labeled cells’ luminescence intensity and intracellular glucose concentration. Additionally, we developed dual-emission probes by modifying red-emitting GOx-AuNCs with green-emitting BDP-FL for ratiometric imaging of intracellular glucose concentration, enhancing glucose sensing precision in biological environments.

Horseradish peroxidase-catalyzed polyacrylamide gels: monitoring their polymerization with BSA-stabilized gold nanoclusters and their functional validation in electrophoresis.

Polyacrylamide gel (PAG) is extensively used as a matrix for biomolecular analysis and fractionation. However, the traditional polymerization catalyst system N,N,N',N'-tetramethylethylenediamine (TEMED)/ammonium persulphate (APS) of PAG presents non-negligible toxicity. Herein, we utilized the green and efficient bio-enzyme horseradish peroxidase (HRP) to catalyze the gel polymerization of polyacrylamide. At the same time, the efficacy of this gel system in separating nucleic acids and proteins was confirmed by applying the gel system in electrophoresis. This study aims to explore a higher biosafety polyacrylamide gel polymerization catalytic system which can be applied to electrophoresis technology. Furthermore, in order to differentiate between the bio-enzymatic catalytic system and the traditional toxic catalytic system during polymerization, aggregation-induced luminescence (AIE) of bovine serum albumin-stabilized gold nanoclusters (BSA-Au NCs) was used to monitor the polymerization reaction of the system. The results indicated that the fluorescence intensity of the polymeric system containing BSA-Au NCs increased with the polymerization of the monomers. Subsequently, we assessed whether certain components of nucleic acid electrophoresis and protein electrophoresis such as sodiumdodecylsulfate (SDS) and TBE buffer (Tris-boric acid, EDTA, pH 8.3) would affect the polymerization of the polyacrylamide gels catalyzed by the biological enzymes. The experimental conditions were also optimized to explore the optimal concentration of the ternary system of HRP, H2O2 and ACAC. Our results suggested that the bioenzyme-catalyzed system could be a feasible alternative to the TEMED/APS-catalyzed system, which also could provide new insights into the methods of monitoring the polymerization system.

Detection and imaging of bacterial biofilms with glutathione-stabilized gold nanoclusters

Bacterial biofilms colonize chronic wounds and surfaces of medical devices, thus making the development of reliable methods for imaging and detection of biofilms crucial. Although fluorescent identification of bacteria is sensitive and non-destructive, the lack of biofilm-specific fluorescent dyes limits the application of this technique to biofilm detection. Here, we demonstrate, for the first time, that fluorescent glutathione-stabilized gold nanoclusters (GSH-AuNCs) without targeting ligands can specifically interact with extracellular matrix components of Gram-negative and Gram-positive bacterial biofilms resulting in fluorescent staining of bacterial biofilms. By contrast, fluorescent bovine serum albumin-stabilized gold nanoclusters and 11-mercaptoundecanoic acid – stabilized gold nanoclusters do not stain the extracellular matrix of biofilms. According to molecular docking studies, GSH-AuNCs show affinity to several targets in extracellular matrix, including amyloid-anchoring proteins, matrix proteins and polysaccharides. Some experimental evidence was obtained for the interaction of GSH-AuNCs with the lipopolysaccharide (LPS) that was isolated from the matrix of Azospirillum baldaniorum biofilms. Based on GSH-AuNCs properties, we propose a new fluorescent method for the measurement of biofilm biomass with a limit of detection 1.7 × 105 CFU/mL. The sensitivity of the method is 10-fold higher than the standard biofilm quantification with the crystal violet assay. There is a good linear relationship between the fluorescence intensity from the biofilms and the number of CFU from the biofilms in the range from 2.6 × 105 to 6.7 × 107 CFU/mL. The developed nanocluster-mediated method of biofilm staining was successfully applied for quantitative detection of biofilm formation on urinary catheter surface. The presented data suggest that fluorescent GSH-AuNCs can be used to diagnose medical device-associated infections.

Gold Nanoclusters and Silica-Coated Carbon Dots-Assisted Ratiometric Fluorescent Nanosensors for Ultrasensitive Detection of Glyphosate

In this work, a novel ratiometric fluorescent nanosensor by coupling mesoporous silica spheres-coated nitrogen-doped carbon dots (N-CDs@SiO2) and bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs) was developed for sensitive detection of glyphosate. BSA-AuNCs nanocomposites were covalently connected onto the surface of amino-functionalized N-CDs@SiO2 nanospheres, causing the core-satellite probes with two fluorescence emissions at 436 and 651 nm, respectively, under a single excitation of 360 nm. The N-CDs@SiO2@BSA-AuNCs “signal on–off–on” ratiometric fluorescent probes could realize highly selective differentiation and accurate detection of glyphosate based on the fluorescence quenching of Cu2+ on BSA-AuNCs and glyphosate-induced fluorescence recovery due to the strong complexation of glyphosate toward Cu2+. The developed ratiometric fluorescent nanosensor exhibited excellent selectivity to glyphosate, wide detectability in a concentration range of 5–100 ng/mL, high sensitivity with a low detection limit of 3.4 ng/mL, as well as fascinating reliability and practicability in real malt samples with recoveries of 94.81–101.61%. This study provides a universal platform for versatile sensing of more trace analytes in complex matrices and can be extended for wide application in the environment and food safety fields.

Horseradish Peroxidase-Encapsulated Fluorescent Bio-Nanoparticle for Ultra-Sensitive and Easy Detection of Hydrogen Peroxide.

Hydrogen peroxide (H2O2) has been a fascinating target in various chemical, biological, clinical, and industrial fields. Several types of fluorescent protein-stabilized gold nanoclusters (protein-AuNCs) have been developed for sensitive and easy detection of H2O2. However, its low sensitivity makes is difficult to measure negligible concentrations of H2O2. Therefore, to overcome this limitation, we developed a horseradish peroxidase-encapsulated fluorescent bio-nanoparticle (HEFBNP), comprising bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs) and horseradish peroxidase-stabilized gold nanoclusters (HRP-AuNCs). The fabricated HEFBNP can sensitively detect H2O2 owing to its two properties. The first is that HEFBNPs have a continuous two-step fluorescence quenching mechanism, which comes from the heterogenous fluorescence quenching mechanism of HRP-AuNCs and BSA-AuNCs. Second, the proximity of two protein-AuNCs in a single HEFBNP allows a reaction intermediate (•OH) to rapidly reach the adjacent protein-AuNCs. As a result, HEFBNP can improve the overall reaction event and decrease the loss of intermediate in the solution. Due to the continuous quenching mechanism and effective reaction event, a HEFBNP-based sensing system can measure very low concentrations of H2O2 up to 0.5 nM and show good selectivity. Furthermore, we design a glass-based microfluidic device to make it easier use HEFBNP, which allowed us to detect H2O2 with the naked eye. Overall, the proposed H2O2 sensing system is expected to be an easy and highly sensitive on-site detection tool in chemistry, biology, clinics, and industry fields.

Bovine serum albumin-stabilized gold nanoclusters as fluorescent probe for enzyme-free detection of glyphosate

Bovine serum albumin-stabilized gold nanoclusters as fluorescent probe for enzyme-free detection of glyphosate

The photo-activated oxidase-like activity of gold nanoclusters: Implication for singlet oxygen generation

Gold-based nanomaterials have been widely used as photocatalysts, but little is known about their catalytic mechanism. In this work, we systematically investigated the oxidase-like activity of bovine serum albumin-stabilized gold nanoclusters (BSA-Au25NCs) and gold nanoparticles (AuNPs) upon with different wavelengths. Our experiments showed that only BSA-Au25NCs could possess the photo-activated oxidase-like activity because the generation of reactive oxygen species (ROS) from BSA-Au25NCs was relatively efficient as compared to that of AuNPs. In addition, the interaction of BSA-Au25NCs with copper ions (Cu2+) further verified that singlet oxygen (1O2) was the key reactive species in the dominant involvement of the photo-oxidase reaction. This work provides new insight into regulating the 1O2 generation of BSA-Au25NCs, which might help in the design of AuNCs for other photocatalytic and photodynamic applications.

Microwave-assisted ultra-fast synthesis of bovine serum albumin-stabilized gold nanoclusters and in-situ generation of manganese dioxide to detect alkaline phosphatase

Alkaline phosphatase (ALP) is a kind of biological hydrolase which plays a key role in the normal growth of the body. Therefore, it is necessary to establish a simple and accurate method for quantitative detection of ALP. In this work, gold nanoclusters with bovine serum albumin as a template (BSA-AuNCs) were rapidly synthesized in 20 s based on microwave-assisted. Subsequently, manganese dioxide (MnO2) was generated in situ on the surface of the gold nanoclusters which quenched the fluorescence of BSA-AuNCs. The quenching mechanism was explored and found that it was through the combined effect of fluorescence resonance energy transfer and inner filter effect. The quantitative detection of ALP was achieved through a simple enzymatic reaction and a redox reaction. The developed method was simple and convenient, and the detection limit for ALP was 1.5 mU mL−1. In addition, this fluorescence sensor had good selectivity and could accurately detect ALP in human serum, which demonstrated its potential applications in clinical diagnosis.

Circularly Polarized Luminescent Chiral Photonic Films Based on the Coassembly of Cellulose Nanocrystals and Gold Nanoclusters.

In this work, we studied the formation and properties of composite films coassembled by cellulose nanocrystals (CNCs) and bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs). The influences of the BSA-AuNC concentration on the structure and optical properties of CNC-based composite films were further studied. It was found that the composite film retained the chiral nematic structure and optical activity. The self-assembled CNC and BSA-AuNC helical superstructures can produce strong, left-handed, circularly polarized luminescence with dissymmetry factors up to 0.287. Meanwhile, the third component, polyethylene glycol, was introduced without affecting the structural color and fluorescence characteristics of the composite film to enhance the flexibility of the film. The simplicity of the film preparation, the abundance of CNCs, and the flexibility and stability of the composite films pave the way for the production of functional materials with integrated functions.

The recognition of aristolochic acid I based on fluorescence quenching of bovine serum albumin-stabilized gold nanoclusters.

Aristolochic acid I (AAI) is one of the nephrotoxic derivatives present in genera Aristolochia and Asarum. Although some detection strategies for monitoring AAI have been reported, the application of these methods is limited because they involve tedious preparation and require professional operation. In this work, bovine serum albumin (BSA) has been introduced as a reducing agent and stabilizing agent to synthesize gold nanoclusters with strong red fluorescence for the rapid and effective detection of AAI. Under excitation at 328 nm, the fluorescence intensity at the maximum emission wavelength of the bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs) decreased with the addition of AAI, and the degree of quenching showed a linear relationship with the concentration of AAI from 0.1-12.8 μg mL-1. The obtained BSA-AuNCs were stable, and quenching in the presence of AAI could be achieved within 10 seconds. Here, we have focused on the application of these gold nanoclusters as an optical sensing material for AAI in rat urine samples, including a discussion on the detection mechanism. The detection result of the fluorescent probe was consistent with that of the HPLC method. In view of this reality, the reported protein-AuNCs sensing platform can serve as a convenient detection strategy in toxicological analyses.

One-pot synthesis of boron and nitrogen co-doped silicon-carbon dots for fluorescence enhancement and on-site colorimetric detection of dopamine with high selectivity

The boron and nitrogen co-doped silicon-carbon dots (BN-SiCDs) were synthesized by one-pot method. The introduction of boron in BN-SiCDs played a significant role to selectively respond to dopamine (DA) based on fluorescence enhancement, while almost no respond to structural analogues, i.e. norepinephrine and epinephrine. The hydrogen bonds and π-π conjugation between BN-SiCDs and DA oligomers, and the polymerization nature of DA could be contributing factors to this phenomenon. BN-SiCDs were employed as the fluorescent nanoprobe to determine DA with the linearity of 0.005–10 μg mL−1, and limit of detection of 1.58 ng mL−1. For on-site detection, the fluorescence colorimetric probe was constructed based on BN-SiCDs and bovine serum albumin-stabilized gold nanoclusters. The sensitive color change from red to blue-green was visually observed by naked eyes corresponding to DA concentration of 0–9 μg mL−1. Further combined with the APP by the smartphone, the colorimetric probe was used for the quantitative detection. The proposed BN-SiCDs probe, colorimetric system or APP method were applied to determine DA in hydrochloride dopamine injection and human urine samples, and results agreed well with each other. The present study provided an effective strategy to adjust properties of fluorescent nanoprobes from synthetic sources to realize high selective detection.

Light-responsive Au nanoclusters with oxidase-like activity for fluorescent detection of total antioxidant capacity

A fluorescent assay for total antioxidant capacity (TAC) detection based on the light-responsive oxidase-like activity of bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs) has been developed. Thiamine (TH) as the peroxidase substrate usually works at alkaline conditions and thus limits its practical applications. Here, by utilization the light-responsive oxidase-like activity of BSA-AuNCs, TH is oxidized to fluorescent thiochrome under neutral condition in two minutes due to the single oxygen generated by BSA-AuNCs upon light irradiation. After the introduction of antioxidants into the BSA-AuNCs-TH system, the formation of thiochrome is inhibited resulting in the fluorescence decrease. On the basis of the above facts, BSA-AuNCs-TH-based assay has been fabricated and applied successfully to detect antioxidants and the TAC of vitamin C tablets as well as some commercial fruit juice with satisfied results. This work may provide novel insights into developing light-responsive nanozymes-based fluorescent assays.

Ratiometric fluorescence determination of alkaline phosphatase activity based on dual emission of bovine serum albumin-stabilized gold nanoclusters and the inner filter effect.

A novel and convenient method for the ratiometric fluorescence detection of alkaline phosphatase (ALP) activity was proposed based on dual emission of bovine serum albumin-templated gold nanoclusters (BSA-AuNCs) and the mechanism of the inner filter effect between BSA-AuNCs and p-nitrophenol (PNP). First, ALP catalyzed the hydrolysis of the substrate p-nitrophenyl phosphate (PNPP) to produce PNP. PNP effectively quenched the emission peak of BSA-AuNCs at 410 nm because of the overlap in absorbance feature of PNP and the fluorescence spectrum of BSA-AuNCs, and the peak at 650 nm was almost unaffected. Thus, a sensitive ratiometric method for detection of ALP activity was developed using the fluorescence intensity of BSA-AuNCs at 650 nm as a reference signal. ALP activity versus the ratio of fluorescence intensities at 410 and 650 nm showed good linearity between 0.2 and 5 mU mL-1 (R2 = 0.9931) and high sensitivity with a detection limit of 0.03 mU mL-1 (S/N = 3). The developed sensing method was successfully applied to investigate ALP inhibitors and detect ALP in serum samples.

Fluorescence Quenchers Manipulate the Peroxidase-like Activity of Gold-Based Nanomaterials.

Although the regulation of the enzyme-like activities of nanozymes has stimulated great interest recently, the exploration of modulators makes it possible to enhance the catalytic performance of nanozymes, though doing so remains a big challenge. Herein, we systemically studied the effects of fluorescence quenchers on the peroxidase-like activity of bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs) based on photoinduced electron transfer (PET). We found that PET quenchers can not only quench the fluorescence of BSA-AuNCs but also regulate their intrinsic peroxidase-like activity. Importantly, both BSA and human serum albumin (HSA) could enhance the peroxidase-like activity of Cu2+, which provided a new sensing platform for distinguishing BSA and HSA from other thiol-containing biomolecules. The PET quenchers could also manipulate the peroxidase-like activity of polyvinylpyrrolidone-stabilized gold nanoparticles (PVP-AuNPs), which exhibited some opposite results between PVP-AuNPs and BSA-AuNCs. The opposite effects on BSA-AuNCs and PVP-AuNPs were speculated to highly depend on their surface properties. Our findings offer an efficient strategy for tuning the peroxidase-like activities of gold-based nanozymes.

Foldable paper-based analytical device for membraneless gas-separation and determination of iodate based on fluorescence quenching of gold nanoclusters

A new design of a paper-based analytical device (PAD) for membraneless gas-separation with subsequent determination of iodate is presented. The rectangular PAD was invented as the folded pattern, where two circular reservoirs: the donor reservoir and the acceptor reservoir were situated in “a single paper” for convenient use. The hydrophobic barrier of each reservoir was easily fabricated by painting with a permanent marker. The PAD was demonstrated for the quantitative analysis of iodate, based on the fluorescence quenching of the bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs). The BSA-AuNCs were fast prepared by a microwave-assisted approach. The nanoclusters solution was applied into the acceptor reservoir, while the sample, iodide and sulfuric acid were sequentially aliquoted into the donor reservoir. After folding the PAD, the donor and the acceptor were mounted together via a two-sided mounting tape. The headspace between the two reservoirs allows membraneless gas-separation of free iodine from the donor to diffuse into the acceptor. Etching of gold core of the nanoclusters in the acceptor resulted in quenching of the red emission, was monitored by two methods, i.e. “fluorometric detection” (λex: 490 nm, λem: 630 nm) and “image capture” of the acceptor under the UV irradiation by a smart phone's camera. Two calibrations were plotted accordingly to their detections and good linearities (r2 ˃ 0.98) were observed from 0.005 to 0.1 mmol L−1 iodate. High accuracy (mean recovery: 95.1 (±4.6) %) and high precision (RSD < 3%) were obtained. The lower limits of detection were 0.005 mmol L−1 (with fluorometric detection) and 0.01 mmol L−1 (with image capture). The method was effectively applied for the measurement of iodate in iodized salts and fish sauces without prior sample pre-treatment.

Enhancement of the peroxidase-like activity of aptamers modified gold nanoclusters by bacteria for colorimetric detection of Salmonella typhimurium

A colorimetric aptasensor was developed for selective and sensitive detection of Salmonella typhimurium (S. typhimurium) based on the enhancement of bacteria for the peroxidase-like activity of dual aptamers modified bovine serum albumin stabilized-gold nanoclusters (aptamers@BSA-AuNCs). Micro-sized bacteria was found to be able to capture aptamers@BSA-AuNCs and 3,3′,5,5′-tetramethylbenzidine (TMB), thus promoting the proximity of aptamers@BSA-AuNCs to TMB and greatly increasing the local concentrations of the enzyme-mimetic nanoparticles and their substrate. As a result, addition of bacteria promoted the formation of blue products in the catalytic system, which was utilized to achieve bacteria detection by colorimetry. The parameters influencing the colorimetric aptasensor were optimized by an orthogonal test. Under the selected conditions, the aptasensor exhibited a wide linear response to S. typhimurium in the concentration range of 101–106 cfu mL−1 with a detection limit as low as 1 cfu mL−1. The feasibility of the aptasensor was verified by successful detection of S. typhimurium in egg samples with recoveries in the range of 92.4%–110%.

A simple, quantitative method for spectroscopic detection of metformin using gold nanoclusters.

We synthesized bovine serum albumin (BSA)-stabilized gold nanoclusters (BSA-GNCs) and confirmed their ultra-small size using HRTEM (High-resolution Transmission Electron Microscope) and DLS (Dynamic Light Scattering). The fluorescence intensity of BSA-GNCs is "turned off" in the presence of Cu(II) metal ions. The resulting Cu(II)-mediated BSA-GNCs were utilized to detect metformin, a drug used to control diabetes. Metformin binds to and displaces Cu(II) ions from the BSA on the surface of the nanoclusters, which turns on the fluorescence of the nanoclusters. The interactions between the protein-stabilized nanoclusters were investigated in the absence and presence of Cu(II) using circular dichroism (CD) and Fourier-transform infrared spectroscopy (FTIR). Cu(II)-quenched BSA-GNCs had an extremely high sensitivity to detect metformin, with a low limit of detection (LOD) of 0.068μM and a dynamic range of limit of quantification (LOQ=10/3 LOD) of 0.22 to 11μM. The ability of this novel "turn-on" nanosensor to detect metformin in human serum and urine samples was confirmed: the percentage recovery in fluorescence for spiked analyte ranged from 96.00-98.50% and 92.60-96.62% in human serum and urine samples, respectively. Thus, BSA-GNCs provide a valid, sensitive, specific fluorometric methodology for the detection of metformin in biomedical applications.

Gold nanoclusters-based dual-channel assay for colorimetric and turn-on fluorescent sensing of alkaline phosphatase

Here, based on their bifunctional peroxidase-mimicking activity and fluorescence of bovine serum albumin-stabilized gold nanoclusters (BSA-AuNCs), we develop a colorimetric and fluorescent dual-channel assay for alkaline phosphatase activity determination. The peroxidase-like activity of BSA-AuNCs makes it possible to catalyze the oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) into its blue product (oxTMB) in the presence of H2O2, and result in the fluorescence quench of BSA-AuNCs simultaneously due to the inner filter effect between oxTMB and BSA-AuNCs. While the ascorbic acid generating form alkaline phosphatase (ALP)-catalyzed hydrolysis of L-ascorbic acid-2-phosphate can inhibit the oxidation of TMB, thereby inducing decolorization of oxTMB and fluorescence recovery of BSA-AuNCs. Based on these findings, a dual-readout assay for ALP activity sensing using BSA-AuNCs has been reported for the first time. The detection limitation can reach as low as 0.26 and 0.16 mU mL-1 by colorimetric and fluorescent method, respectively. Moreover, the developed assay has been successfully applied to detect ALP in human serum samples with satisfactory results. This method may not only offer new idea for simple, sensitive and accurate detection of ALP activity, but also broaden the applications of BSA-AuNCs in bioanalysis.

A Photoluminescent Colorimetric Probe of Bovine Serum Albumin-Stabilized Gold Nanoclusters for New Psychoactive Substances: Cathinone Drugs in Seized Street Samples.

Screening of illicit drugs for new psychoactive substances—namely cathinone—at crime scenes is in high demand. A dual-emission bovine serum albumin-stabilized gold nanoclusters probe was synthesized and used for quantitation and screening of 4-chloromethcathinone and cathinone analogues in an aqueous solution. The photoluminescent (PL) color of the bovine serum albumin-stabilized Au nanoclusters (BSA-Au NCs) probe solution changed from red to dark blue during the identification of cathinone drugs when excited using a portable ultraviolet light-emitting diodes lamp (365 nm). This probe solution allows the PL color-changing point and limit of detection down to 10.0 and 0.14 mM, respectively, for 4-chloromethcathinone. The phenomenon of PL color-changing of BSA-Au NCs was attributed to its PL band at 650 nm, quenching through an electron transfer mechanism. The probe solution was highly specific to cathinone drugs, over other popular illicit drugs, including heroin, cocaine, ketamine, and methamphetamine. The practicality of this BSA-Au NCs probe was assessed by using it to screen illicit drugs seized by law enforcement officers. All 20 actual cases from street and smuggling samples were validated using this BSA-Au NCs probe solution and then confirmed using gas chromatography–mass spectrometry. The results reveal this BSA-Au NCs probe solution is practical for screening cathinone drugs at crime scenes.

Protein-Nanoparticle Agglomerates as a Plasmonic Magneto-Luminescent Multifunctional Nanocarrier for Imaging and Combination Therapy.

We report the fabrication of a plasmonic magneto-luminescent multifunctional nanocarrier (PML-MF nanocarrier) by lysozyme-mediated agglomeration of gold-coated iron oxide nanoparticles (IO@AuNPs) and subsequent coating of these agglomerates with BSA-stabilized gold nanoclusters (BSA-AuNCs). The agglomeration-mediated enhancement of plasmonic absorbance at the NIR biological window helped in plasmonic photothermal therapy (PPTT) by PML-MF nanocarriers. PML-MF nanocarriers demonstrated excellent in vitro bioimaging and magnetic targeting capabilities due to the strong photoluminance and superparamagnetism of the constituent AuNCs and IO@AuNPs, respectively. Moreover, these nanocarriers showed the successful loading and delivery of doxorubicin to cancer cells with a significant killing efficiency that could be synergistically improved by combining with PPTT.