Electrostatic selectivity in protein-nanoparticle interactions

Application of Monte Carlo simulation in addressing key issues of complex coacervation formed by polyelectrolytes and oppositely charged colloids

This paper reviews the recent advance of Monte Carlo (MC) simulation in addressing key issues of complex coacervation between polyelectrolytes and oppositely charged colloids. Readers were first supplied with a brief overview of current knowledge and experimental strategies in the study of complex coacervation. In the next section, the general MC simulation procedures as well as representative strategies applied in complex coacervation were summarized. The unique contributions of MC simulation in either capturing delicate features, easing the experimental trials or proving the concept were then elucidated through the following aspects: i) identify phase boundary and decouple interaction contributions; ii) clarify composition distribution and internal structure; iii) predict the influences of physicochemical conditions on complex coacervation; iv) delineate the mechanisms for "binding on the wrong side of the isoelectric point". Finally, current challenges as well as prospects of MC simulation in complex coacervation are also discussed. The ultimate goal of this review is to provide readers with basic guideline for synergistic design of experiments in combination with MC simulation, and deliver convincing interpretation and reliable prediction for the structure and behavior in polyelectrolyte-macroion complex coacervation.

Association models for binding of molecules to nanostructures

The interaction between nanoparticles and molecules determines the activity of nanostructures.

Tuning of surface protein adsorption by spherical mixed charged silica brushes (MCB) with zwitterionic carboxybetaine component

Controlled protein adsorption and release without deformation and loss of activity under mild conditions is an essential issue for biological carriers. A spherical mixed charged silica brush (MCB), which could tune protein adsorption, has been prepared by introducing zwitterionic carboxybetaine copolymer onto the surface of silica nanoparticles for the first time. The simple surface-initiated reversible addition-fragmentation chain transfer polymerization (SI-RAFT) was applied to synthesize the MCB precursor - poly(2-(dimethylamino)ethyl methacrylate) modified silica nanoparticles (SiO₂@PDMAEMA). Then, the end group in PDMAEMA was quaternized with propiolactone to obtain poly(DMAEMA-co-carboxybetaine methacrylate) modified silica nanoparticles (SiO₂@poly(DMAEMA-co-CBMA)), which was denoted as MCB. In comparison, fully quaternized MCB (SiO₂@PCBMA) was also prepared by a one-step strategy. Physicochemical behaviours of MCB in solution were systematically studied. The zwitterionic CBMA component endows the MCB with tunable adsorption towards both acidic and basic proteins through simple adjustment of the DMAEMA to CBMA ratio under mild conditions. This study may have great potential applications in the biomedical field, including tunable drug loading and releasing, and immobilized enzymes, etc.

Organic chemistry meets polymers, nanoscience, therapeutics and diagnostics

The atom-by-atom control provided by synthetic organic chemistry presents a means of generating new functional nanomaterials with great precision. Bringing together these two very disparate skill sets is, however, quite uncommon. This autobiographical review provides some insight into how my program evolved, as well as giving some idea of where we are going.

Polypeptide-Nanoparticle Interactions and Corona Formation Investigated by Monte Carlo Simulations

Biomacromolecule activity is usually related to its ability to keep a specific structure. However, in solution, many parameters (pH, ionic strength) and external compounds (polyelectrolytes, nanoparticles) can modify biomacromolecule structure as well as acid/base properties, thus resulting in a loss of activity and denaturation. In this paper, the impact of neutral and charged nanoparticles (NPs) is investigated by Monte Carlo simulations on polypeptide (PP) chains with primary structure based on bovine serum albumin. The influence of pH, salt valency, and NP surface charge density is systematically studied. It is found that the PP is extended at extreme pH, when no complex formation is observed, and folded at physiological pH. PP adsorption around oppositely-charged NPs strongly limits chain structural changes and modifies its acid/base properties. At physiological pH, the complex formation occurs only with positively-charged NPs. The presence of salts, in particular those with trivalent cations, introduces additional electrostatic interactions, resulting in a mitigation of the impact of negative NPs. Thus, the corona structure is less dense with locally-desorbed segments. On the contrary, very limited impact of salt cation valency is observed when NPs are positive, due to the absence of competitive effects between multivalent cations and NP.

Regulation of Macrophage Recognition through the Interplay of Nanoparticle Surface Functionality and Protein Corona

Using a family of cationic gold nanoparticles (NPs) with similar size and charge, we demonstrate that proper surface engineering can control the nature and identity of protein corona in physiological serum conditions. The protein coronas were highly dependent on the hydrophobicity and arrangement of chemical motifs on NP surface. The NPs were uptaken in macrophages in a corona-dependent manner, predominantly through recognition of specific complement proteins in the NP corona. Taken together, this study shows that surface functionality can be used to tune the protein corona formed on NP surface, dictating the interaction of NPs with macrophages.

Impact of Proteins on Aggregation Kinetics and Adsorption Ability of Hematite Nanoparticles in Aqueous Dispersions

The initial aggregation kinetics of hematite nanoparticles (NPs) that were conjugated with two model globular proteins-cytochrome c from bovine heart (Cyt) and bovine serum albumin (BSA)-were investigated over a range of monovalent (NaCl) and divalent (CaCl2) electrolyte concentrations at pH 5.7 and 9. The aggregation behavior of Cyt-NP conjugates was similar to that of bare hematite NPs, but the additional electrosteric repulsion increased the critical coagulation concentration (CCC) values from 69 mM to 113 mM in NaCl at pH 5.7. An unsaturated layer of BSA, a protein larger than Cyt, on hematite NPs resulted in fast aggregation at low salt concentrations and pH 5.7, due to the strong attractive patch-charge interaction. However, the BSA-NP conjugates could be stabilized simply by elevating salt concentrations, owing to the screening of the attractive patch-charge force and the increasing contribution from steric force. This study showed that the aggregation state of protein-conjugated NPs is proved to be completely switchable via ionic strength, pH, protein size, and protein coverage. Macroscopic Cu(II) sorption experiments further established that reducing aggregation of hematite NPs via tailoring ionic strength and protein conjugation could promote the metal uptake by hematite NPs under harsh conditions.

Photoreduction of natural redox proteins by CdTe quantum dots is size-tunable and conjugation-independent

Colloidal CdTe quantum dots may photoreduce both heme and iron–sulfur cluster containing proteins. Reduction level may be tuned by choosing different size of nanocrystals.

Enhancement of enzymatic activity by magnetic spherical polyelectrolyte brushes: a potential recycling strategy for enzymes

Interactions between amyloglucosidase and magnetic spherical polyelectrolyte brushes (MSPB) were studied by turbidimetric titration, which reveals reversible and tunable behaviors of pH-dependent enzyme-SPB binding. Quantitative thermodyanmic parameters including binding affinity and stoichiometry between enzyme and SPBs were further measured by isothermal titration calorimetry (ITC). A large amount of enzyme can be loaded in MSPB without loss of MSPB stability. We demonstrated that the enzymatic activity of amyloglucosidase bound in MSPB could be greatly enhanced (catalytic reaction rate, k(bound) = 1.36k(free)) compared to free enzyme acitivity in solution. This is tremendous improvement from other carrier systems that usually lead to a significant decrease of enzymatic activity. Both the high enzyme loading capacity and the enhancement of the catalytic activity probably arise from the Coulombic interactions between the enzyme and MSPB. These findings provide a practical strategy for enhancement of enzyme activity and enzyme recycling by MSPB.

Effects of surface compositional and structural heterogeneity on nanoparticle-protein interactions: different protein configurations

As nanoparticles (NPs) enter into biological systems, they are immediately exposed to a variety and concentration of proteins. The physicochemical interactions between proteins and NPs are influenced by the surface properties of the NPs. To identify the effects of NP surface heterogeneity, the interactions between bovine serum albumin (BSA) and gold NPs (AuNPs) with similar chemical composition but different surface structures were investigated. Different interaction modes and BSA conformations were studied by dynamic light scattering, circular dichroism spectroscopy, fluorescence quenching and isothermal titration calorimetry (ITC). Depending on the surface structure of AuNPs, BSA seems to adopt either a "side-on" or an "end-on" conformation on AuNPs. ITC demonstrated that the adsorption of BSA onto AuNPs with randomly distributed polar and nonpolar groups was primarily driven by electrostatic interaction, and all BSA were adsorbed in the same process. The adsorption of BSA onto AuNPs covered with alternating domains of polar and nonpolar groups was a combination of different interactions. Overall, the results of this study point to the potential for utilizing nanoscale manipulation of NP surfaces to control the resulting NP-protein interactions.

Optimizing the selective recognition of protein isoforms through tuning of nanoparticle hydrophobicity

We demonstrate that ligand hydrophobicity can be used to increase affinity and selectivity of binding between monolayer-protected cationic gold nanoparticles and β-lactoglobulin protein isoforms containing two amino acid mutations.

Effect of charge regulation and ion-dipole interactions on the selectivity of protein-nanoparticle binding

We investigate the role of different mesoscopic interactions (Coulomb, charge regulation, and ion-dipole "surface patch" effects) on the binding of bovine serum albumin (BSA) and β-lactoglobulin (BLG) to a cationic gold nanoparticle (TTMA+). The results demonstrate that the charge-regulation mechanism plays a vital role for selectivity of protein-nanoparticle complexation at low salt concentration. At slightly higher ionic strengths, charge-dipole effects are the dominating driving force. Thus, very small variations in salt concentration strongly influence the origin of complexation.

Critical adsorption of polyelectrolytes onto charged Janus nanospheres

The conditions of critical polyelectrolyte adsorption onto spherical charged Janus nano-particles are exploited by Monte-Carlo computer simulations and theoretically.

Heparin decamer bridges a growth factor and an oligolysine by different charge-driven interactions

Full-length heparin is widely used in tissue engineering applications due its multiple protein-binding sites that allow it to retain growth factor affinity while associating with oligopeptide components of the tissue scaffold. However, the extent to which oligopeptide coupling interferes with cognate protein binding is difficult to predict. To investigate such simultaneous interactions, we examined a well-defined ternary system comprised of acidic fibroblast growth factor (FGF), tetralysine (K4), with a heparin decamer (dp10) acting as a noncovalent coupler. Electrospray ionization mass spectrometry was used to assess binding affinities and complex stoichiometries as a function of ionic strength for dp10·K4 and FGF·dp10. The ionic strength dependence of K4·dp10 formation is qualitatively consistent with binding driven by the release of condensed counterions previously suggested for native heparin with divalent oligopeptides (Mascotti, D. P.; Lohman, T. M. Biochemistry 1995, 34, 2908-2915). On the other hand, FGF binding displays more complex ionic strength dependence, with higher salt resistance. Remarkably, dp10 that can bind two FGF molecules can only bind one tetralysine. The limited binding of K4 to dp10 suggests that the tetralysine might not block growth factor binding, and the 1:1:1 ternary complex is indeed observed. The analysis of mass distribution of the bound dp10 chains in FGF·dp10, FGF2·dp10, and FGF·dp10·K4 complexes indicated that higher degrees of dp10 sulfation promote the formation of FGF2·dp10 and FGF·dp10·K4. Thus, the selectivity of appropriately chosen short heparin chains could be used to modulate growth factor sequestration and release in a way not feasible with heterogeneous native heparin. In support of this, human hepatocellular carcinoma cells (HEP3Bs) treated with FGF·dp10·K4 were found to exhibit biological activity similar to cells treated with FGF.

Controlling mixed-protein adsorption layers on colloidal alumina particles by tailoring carboxyl and hydroxyl surface group densities

We show that different ratios of bovine serum albumin (BSA) and lysozyme (LSZ) can be achieved in a mixed protein adsorption layer by tailoring the amounts of carboxyl (-COOH) and aluminum hydroxyl (AlOH) groups on colloidal alumina particles (d50 ≈ 180 nm). The particles are surface-functionalized with -COOH groups, and the resultant surface chemistry, including the remaining AlOH groups, is characterized and quantified using elemental analysis, ζ potential measurements, acid-base titration, IR spectroscopy, electron microscopy, nitrogen adsorption, and dynamic light scattering. BSA and LSZ are subsequently added to the particle suspensions, and protein adsorption is monitored by in situ ζ potential measurements while being quantified by UV spectroscopy and gel electrophoresis. A comparison of single-component and sequential protein adsorption reveals that BSA and LSZ have specific adsorption sites: BSA adsorbs primarily via AlOH groups, whereas LSZ adsorbs only via -COOH groups (1-2 -COOH groups on the particle surface is enough to bind one LSZ molecule). Tailoring such groups on the particle surface allows control of the composition of a mixed BSA and LSZ adsorption layer. The results provide further insight into how particle surface chemistry affects the composition of protein adsorption layers on colloidal particles and is valuable for the design of such particles for biotechnological and biomedical applications.

Synthesis and characterization of jacalin-gold nanoparticles conjugates as specific markers for cancer cells

New nanobiocomposites that combine nanoparticles and biomolecules have been shown very relevant for medical applications. Recently, cancer diagnostics and treatment have benefited from the development of nanobiocomposites, in which metallic or magnetic nanoparticles are conjugated with specific biomolecules for selective cell uptake. Despite recent advances in this area, the biomedical applications of these materials are still limited by the low efficiency of functionalization, low stability, among other factors. In this study, we report the synthesis of jacalin-conjugated gold nanoparticles, a nanoconjugate with potential application in medical areas, especially for cancer diagnosis. Jacalin is a lectin protein and it was employed due to its ability to recognize the Galβ1-3GalNAc disaccharide, which is highly expressed in tumor cells. Gold nanoparticles (AuNPs) were synthesized in the presence of generation 4 polyamidoamine dendrimer (PAMAM G4) and conjugated with fluorescein isothiocyanate (FITC)-labeled jacalin. The AuNPs/jacalin nanoconjugates were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and vibrational spectroscopy (FTIR). We also performed an investigation using isothermal titration calorimetry (ITC) and fluorescence quenching measurements to understand the interactions occurring between the AuNPs and jacalin, which revealed that the nanoconjugate formation is driven by an entropic process with good affinity. Furthermore, in vitro tests revealed that the AuNPs/jacalin-FITC nanoconjugates exhibited higher affinity for leukemic K562 cells than for healthy mononuclear blood cells, which could be useful for biomedical applications, including cancer cells imaging.

Size control of laser-fabricated surfactant-free gold nanoparticles with highly diluted electrolytes and their subsequent bioconjugation

Size control of laser-fabricated surfactant-free gold nanoparticles is a challenging endeavor. In this work, we show that size control can be achieved by adding ions with low salinity during synthesis. In addition, this approach offers the opportunity to fundamentally study ion interactions with bare nanoparticle surfaces and can help to elucidate the nanoparticle formation mechanism. The studies were carried out in a flow-through reactor and in the presence of NaCl, NaBr and sodium phosphate buffer at minimal ionic strengths. A significant size quenching effect at ionic strengths from 1-50 μM was found, which allowed surfactant-free nanoparticle size control with average diameters of 6-30 nm. This effect went along with low polydispersity and minimal aggregation tendencies and was confirmed by UV-vis spectroscopy, TEM, SEM and analytical disk centrifugation. Our findings indicate that size quenching originates from an anionic electrostatic stabilization depending on the nanoparticle surface area, which may be caused by specific ion adsorption. By subsequent delayed bioconjugation in liquid-flow using bovine serum albumin as a stabilizing agent, nano-bioconjugates with good stability in cell culture media were obtained, which are applicable in toxicology and cell biology.

Binding, unfolding and refolding dynamics of serum albumins

BACKGROUND

The serum albumins (human and bovine serum albumin) occupy a seminal position among all proteins investigated until today as they are the most abundant circulatory proteins. They play the major role of a transporter of many bio-active substances which include various fatty acids, drug molecules, and amino acids to the target cells. Hence, studying the interaction of these serum albumins with different binding agents has attracted enormous research interests from decades. The nature and magnitude of these bindings have direct consequence on drug delivery, pharmacokinetics, therapeutic efficacy and drug design and control.

SCOPE OF THE REVIEW

In the present review, we summarize the binding characteristics of both the serum albumins with surfactants, lipids and vesicles, polymers and dendrimers, nanomaterials and drugs. Finally we have reviewed the effect of various chemical and physical denaturants on these albumins with a special emphasis on protein unfolding and refolding dynamics.

MAJOR CONCLUSIONS

The topic of binding and dynamics of protein unfolding and refolding spans across all areas of inter-disciplinary sciences and will benefit clinical toxicology and medicines. The extensive data from several contemporary research based on albumins will help us to understand protein dynamics in a more illustrious manner.

GENERAL SIGNIFICANCE

These data have immense significance in understanding and unravelling the mechanisms of protein unfolding/refolding and thus can pave the way to prevent protein mis-folding/aggregation which sometimes leads to severe consequences like Parkinson's and Alzheimer's diseases. This article is a part of a Special Issue entitled Serum Albumin. This article is part of a Special Issue entitled Serum Albumin.

Pullulan-based nanoparticles as carriers for transmucosal protein delivery

Polymeric nanoparticles have revealed very effective in transmucosal delivery of proteins. Polysaccharides are among the most used materials for the production of these carriers, owing to their structural flexibility and propensity to evidence biocompatibility and biodegradability. In parallel, there is a preference for the use of mild methods for their production, in order to prevent protein degradation, ensure lower costs and easier procedures that enable scaling up. In this work we propose the production of pullulan-based nanoparticles by a mild method of polyelectrolyte complexation. As pullulan is a neutral polysaccharide, sulfated and aminated derivatives of the polymer were synthesized to provide pullulan with a charge. These derivatives were then complexed with chitosan and carrageenan, respectively, to produce the nanocarriers. Positively charged nanoparticles of 180-270 nm were obtained, evidencing ability to associate bovine serum albumin, which was selected as model protein. In PBS pH 7.4, pullulan-based nanoparticles were found to have a burst release of 30% of the protein, which maintained up to 24h. Nanoparticle size and zeta potential were preserved upon freeze-drying in the presence of appropriate cryoprotectants. A factorial design was approached to assess the cytotoxicity of raw materials and nanoparticles by the metabolic test MTT. Nanoparticles demonstrated to not cause overt toxicity in a respiratory cell model (Calu-3). Pullulan has, thus, demonstrated to hold potential for the production of nanoparticles with an application in protein delivery.

Enhanced Electrostatic Discrimination of Proteins on Nanoparticle-Coated Surfaces

Two β-lactoglobulin (BLG) isoforms, BLGA and BLGB, were used a test bed for the differentiation of proteins using electrostatics. In these studies, the BLGA and BLGB binding to a highly charged, cationic gold nanoparticle (GNP) modified surface was investigated by atomic force microscopy (AFM) and surface plasmon resonance (SPR) spectroscopy The binding affinity, and more importantly, the selectivity of this surface towards these two almost identical protein isoforms were both significantly increased on the cationic GNP surface array relative to the values measured with the same free cationic GNP in solution. While protein recognition is traditionally achieved almost exclusively via orientation dependent short-range interactions such as hydrogen bonds and hydrophobic interactions, our results show the potential of protein recognition platforms based on enhanced electrostatic interactions.

Spectroscopic studies on the interactions between CdTe quantum dots coated with different ligands and human serum albumin

This paper investigates the interactions between human serum albumin (HSA) and CdTe quantum dots (QDs) with nearly identical hydrodynamic size, but capped with four different ligands (MPA, NAC, and GSH are negatively charged; CA is positively charged) under physiological conditions. The investigation was carried out using fluorescence spectroscopy, circular dichroism (CD) spectra, UV-vis spectroscopy, and dynamic light scattering (DLS). The results of fluorescence quenching and UV-vis absorption spectra experiments indicated the formation of the complex of HSA and negatively charged QDs (MPA-CdTe, NAC-CdTe, and GSH-CdTe), which was also reconfirmed by the increasing of the hydrodynamic radius of QDs. The K(a) values of the three negatively charged QDs are of the same order of magnitude, indicating that the interactions are related to the nanoparticle itself rather than the ligands. ΔH<0 and ΔS>0 implied that the electrostatic interactions play predominant roles in the adsorption process. Furthermore, it was also proven that QDs can induce the conformational changes of HSA from the CD spectra and the three-dimensional fluorescence spectra of HSA. However, our results demonstrate that the interaction mechanism between the positively charged QDs (CA-CdTe) and HSA is significantly different from negatively charged QDs. For CA-CdTe QDs, both the static and dynamic quenching occur within the investigated range of concentrations. According to the DLS results, some large-size agglomeration also emerged.

A spectroscopic investigation on the interaction of a magnetic ferrofluid with a model plasma protein: effect on the conformation and activity of the protein

The understanding of the interaction of nanomaterials with relevant biological targets e.g., proteins is of paramount importance in biological and pharmaceutical fields of research. In a biological fluid, proteins can associate with nanomaterials which can subsequently exert a significant impact on the conformation and functionality of the protein. Here we report the binding interaction of a model plasma protein Bovine Serum Albumin (BSA) with a magnetic nanoparticle of mixed spinel origin (Ni(0.5)Zn(0.5)Fe(2)O(4), abbreviated as NZFO from now and onwards). The thermodynamic parameters (ΔH, ΔS and ΔG) for the protein-nanoparticle binding interaction have been evaluated from the van't Hoff equation to unveil that the binding interaction is enthalpically as well as entropically driven (ΔH < 0 and ΔS > 0), with an overall favorable Gibbs free energy change (ΔG < 0). Also the thermodynamic parameters delineate the predominant role of electrostatic interaction in the BSA-NZFO binding process. The results of temperature dependent fluorescence quenching and time-resolved fluorescence decay measurements indicate a static quenching mechanism in the present case. Steady-state absorption, synchronous fluorescence, three-dimensional (3D) fluorescence and circular dichroism (CD) spectroscopic techniques have been employed to unveil the conformational changes in BSA induced by the binding of NZFO. Disruption of the native conformation of the protein upon binding with NZFO is reflected through a reduced functionality (in terms of esterase activity) of the protein-NZFO conjugate system in comparison to the native protein. Based on the experimental findings the probable binding location of NZFO is argued to be the hydrophilic domain IB. This seems physically realizable since domain I of BSA is characterized by a net negative charge and hence can serve as a favorable binding site for NZFO carrying a positive surface charge. The key role of electrostatic forces in the BSA-NZFO interaction process is further substantiated from chemical denaturation study and measurement of the effect of ionic strength on the interaction process.

Gold nanoparticles functionalized with deep-cavity cavitands: synthesis, characterization, and photophysical studies

In this report, we present methods of functionalization of AuNP's with deep-cavity cavitands that can include organic molecules. Two types of deep-cavity cavitand-functionalized AuNP's have been synthesized and characterized, one soluble in organic solvents and the other in water. Functionalized AuNP soluble in organic solvents forms a 1:1 host-guest complex where the guest is exposed to the exterior solvents. The one soluble in water forms a 2:1 host-guest complex where the guest is protected from solvent water. Phosphorescence from thiones and benzil included within heterocapsules attached to AuNP was quenched by gold atoms present closer to the guests included within deep-cavity cavitands. During this investigation, we have synthesized four new deep-cavity cavitands. Of these, two thiol-functionalized hosts allowed us to make stable AuNP's. However, AuNP's protected with two amine-functionalized cavitands tended to aggregate within a day.

Spherical Polyelectrolyte Brushes on Colloidal Poly(butadiene) Particles

A novel method to prepare spherical polyelectrolyte brushes (SPB) on the surface of colloidal poly(butadiene) (PB) core without having to use initiators with C=C double bond to attach covalently on the core surface was reported. Making use of the abundant double bonds in PB, spherical poly(acrylic acid) (PAA) bushes were grown from PB core surface by direct thermo-initiated emulsion polymerization using KPS as initiator. The thickness of SPB increased significantly upon increasing pH and decreasing the ionic strength. The grafting density of SPB with PB core was estimated from the relationship between the brush thickness and ionic strength based on the modified Daoud-Cotton model. The grafting density of SPB prepared by thermo-initiated emulsion polymerization (0.122 nm-2) is higher that that of SPB by photo-emulsion polymerization (0.105 nm-2). Using SPB with PB core as nanoreactors, nickel and silver nanoparticles were prepared by reduction of Ni 2+ and Ag + absorbed inside SPB as counterions. Relatively high catalytic activities for the reduction of p-nitrophenol by NaBH4 were observed for SPB immobilized Ni or Ag nanoparticles.

Probing the behaviors of gold nanorods in metastatic breast cancer cells based on UV-vis-NIR absorption spectroscopy

In this work, behaviors of positively-charged AuNRs in a highly metastatic tumor cell line MDA-MB-231 are examined based on UV-vis-NIR absorption spectroscopy in combination with inductively coupled plasma mass spectrometry (ICP-MS), transmission electron microscopy (TEM) and dark-field microscopic observation. It is found that characteristic surface plasmon resonance (SPR) peaks of AuNRs can be detected using spectroscopic method within living cells that have taken up AuNRs. The peak area of transverse SPR band is shown to be proportionally related to the amount of AuNRs in the cells determined with ICP-MS, which suggests a facile and real time quantification method for AuNRs in living cells. The shape of longitudinal SPR band in UV-vis-NIR spectrum reflects the aggregation state of AuNRs in the cells during the incubation period, which is proved by TEM and microscopic observations. Experimental results reveal that AuNRs are internalized by the cells rapidly; the accumulation, distribution and aggregation of AuNRs in the cells compartments are time and dose dependent. The established spectroscopic analysis method can not only monitor the behaviors of AuNRs in living cells but may also be helpful in choosing the optimum laser stimulation wavelength for anti-tumor thermotherapy.