Biological Buffer Solutions Research Articles

A 2D Zn-MOF as an Efficient Luminescent Sensor for Detecting Cr2O72− in Water Media and HEPES Biological Buffer Solution

A 2D Zn-MOF as an Efficient Luminescent Sensor for Detecting Cr2O72− in Water Media and HEPES Biological Buffer Solution

An amide groups functionalized Cd-MOF as multi-responsive luminescent sensor for detecting Fe3+, Cr2O72− and OTC in water media

Water pollution with toxic heavy metals or antibiotics poses significant safety risks to human survival and health. Luminescent metal–organic frameworks (LMOFs) as sensors can efficiently detect the above contaminants. Herein, a new 2D (two-dimensional) Cd-LMOF LCU-125 (LCU = Liaocheng University) has been fabricated by introducing rich amide active functional sites to serve as a multi-responsive luminescent sensor. As expected, LCU-125 can selective and sensitive sensing Fe3+, Cr2O72− and OTC (oxytetracycline) by quenching effect both in water and HEPES biological buffer solution. Notably, the detection limits (LODs) of Fe3+, Cr2O72− and OTC are as low as 0.0441/0.0084, 0.0849/1.38, and 1.46 μM (OTC in HEPES buffer), respectively. Moreover, a weak interaction quenching mechanism is proposed based on multiple experimental evidences.

Analysis of Selected Properties of Microporous PLA as a Result of Abiotic Degradation.

In the study, an investigation was made into the hydrolytic degradation behavior of the microporous polylactide (PLA) in the initial stage in three biological buffer solutions with various pH-simulating body fluids in comparison with pure PLA. Studies also include the analysis of selected mechanical properties and physical structures. A microporous PLA was obtained by melt extrusion using a chemical blowing agent. The rate of Mw decrease induced by hydrolysis over 35 days of microporous PLA was roughly comparable to the pure material. The rate of depolymerization was slightly accelerated at an acid pH due to acid-catalyzed hydrolysis at the end of the observed period. The mechanical analysis showed the influence of various pH on the obtained results.

Isolation, characterization and in-vitro antigenicity studies of outer membrane proteins (OMPs) of Salmonella gallinarum coated gold nanoparticles (AuNPs)

The development of biomimetic nanoparticles by combining the natural cellular material with synthetic nanoparticles has inspired innovative therapeutic strategies as compared to traditional line of therapeutics. Therefore, the research was conducted to prepare the outer membrane proteins (OMPs) from Salmonella gallinarum and coated on to the surface of synthetic gold nanoparticles (AuNPs). The size of the final product was characterized by Zeta sizer and Zeta potential. The coating of outer membrane proteins onto the gold nanoparticles (AuNPs) was confirmed by transmission electron microscopy (TEM). The sterility, stability and safety of the prepared antigen was confirmed by standard culture media, in biological buffer solution and in-vitro pyrogenic testing, respectively. In-vitro antigenicity of outer membrane protein alone and coated with gold nanoparticles were observed through macrophage phagocytosis assay. On the basis of results, it was anticipated that bacterial outer membrane protein has immunogenic antigenic properties and coating of bacterial outer membrane protein on the surfaces of synthetic gold nanoparticles not only preserved the complex biological characteristics of bacteria but also provided greater immune responses as compared to outer membrane protein alone. So, it was concluded that the coating of bacterial outer membrane proteins on the surface of synthetic gold nanoparticles have synergistic effects to induce the immune responses and promising potential to develop the effective antibacterial vaccine against salmonellosis in poultry birds.

Magnetic and GRPR-targeted reduced graphene oxide/doxorubicin nanocomposite for dual-targeted chemo-photothermal cancer therapy

Herein, we design a rGO-based magnetic nanocomposite by decorating rGO with citrate-coated magnetic nanoparticles (CMNP). The magnetic rGO (mrGO) was modified by phospholipid-polyethylene glycol to prepare PEGylated mrGO, for conjugating with gastrin-releasing peptide receptor (GRPR)-binding peptide (mrGOG). The anticancer drug doxorubicin (DOX) was bound to mrGO (mrGOG) by π-π stacking for drug delivery triggered by the low pH value in the endosome. The mrGOG showed enhanced photothermal effect under NIR irradiation, endorsing its role for dual targeted DOX delivery. With efficient DOX release in the endosomal environment and heat generation from light absorption in the NIR range, mrGOG/DOX could be used for combination chemo-photothermal therapy after intracellular uptake by cancer cells. We characterized the physico-chemical as well as biological properties of the synthesized nanocomposites. The mrGOG is stable in biological buffer solution, showing high biocompatibility and minimum hemolytic properties. Using U87 glioblastoma cells, we confirmed the magnetic drug targeting effect in vitro for selective cancer cell killing. The peptide ligand-mediated targeted delivery increases the efficiency of intracellular uptake of both nanocomposite and DOX up to ~3 times due to the over-expressed GRPR on U87 surface, leading to higher cytotoxicity. The increased cytotoxicity using mrGOG over mrGO was shown from a decreased IC50 value (0.70 to 0.48 μg/mL) and an increased cell apoptosis rate (19.8% to 47.1%). The IC50 and apoptosis rate changed further to 0.19 μg/mL and 76.8% in combination with NIR laser irradiation, with the photothermal effect supported from upregulation of heat shock protein HSP70 expression. Using U87 tumor xenograft model created in nude mice, we demonstrated that magnetic guidance after intravenous delivery of mrGOG/DOX could significantly reduce tumor size and prolong animal survival over free DOX and non-magnetic guided groups. Augmented with NIR laser treatment for 5 min, the anti-cancer efficacy significantly improves with elevated cell apoptosis and reduced cell proliferation. Together with safety profiles from hematological as well as major organ histological analysis of treated animals, the mrGOG nanocomposite is an effective nanomaterial for combination chemo-photothermal cancer therapy.

Electrical Impedance Spectroscopy of plant cells in aqueous biological buffer solutions and their modelling using a unified electrical equivalent circuit over a wide frequency range: 4Hz to 20 GHz

A simple, ultra-wide frequency range, equivalent circuit for plant cell suspensions is presented. The model incorporates both the interfacial interactions of the suspension with the electrode, dominant at low frequencies, and the molecule and cell polarization mechanisms dominant at higher frequencies. Such model is useful for plant cell characterization allowing a single set of parameters over >9 orders of magnitude, whilst allows electronic simulations over the whole frequency range using a single model, simplifying the design of electronic systems of integrated plant cell sensors. The model has been experimentally validated in the frequency range of 4 Hz–20 GHz with each component in the circuit representing a physical phenomenon. Various cell concentrations (MSK8 tomato cells in Murashige and Skoog media) have been investigated, showing clear correlations of the cell capacitance increasing within the range of 200–600 pF, whilst cell resistance (R) decreasing within the range of approximately 0.8–3 kΩ within the cell concentration X–Y cells/mL range. This is the first model ever reported that covers such a wide frequency range and includes both interfacial and polarization effects in this simple form.

One‐Pot Intercalation Strategy for the Encapsulation of a CO‐Releasing Organometallic Molecule in a Layered Double Hydroxide

The photoactivatable CO‐releasing molecule (photoCORM) [Mo(CO)3(CNCH2COOH)3] (ALF795) has been incorporated into a Zn,Al layered double hydroxide (LDH) host by a coprecipitation synthesis strategy. Powder X‐ray diffraction (PXRD) of the resultant material Zn,Al‐ALF795 showed that the ALF795 guest molecules assembled into a monolayer to give a basal spacing of 16.0 Å. FTIR and 13C{1H} CP MAS NMR spectroscopy confirmed that the molecular structure of the tricarbonyl complex was retained upon intercalation. Scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDS) and elemental analyses confirmed the phase‐purity of Zn,Al‐ALF795. The myoglobin assay was used to demonstrate that intercalated ALF795 retains the photoactive behavior of the free CORM, with a substantial fraction (42 %) of the high CO payload (2.46 mmol g–1) being released after exposure to UV light for 3 h under simulated physiological conditions. In addition, gas chromatography was used to track sequential light‐ and H2O2‐triggered decarbonylation of free and intercalated ALF795. In biological buffer solution (HEPES), less than 2 % Mo leaching from Zn,Al‐ALF795 took place after 5 h, showing the strong capacity of the LDH host to retain the unaltered complex and decarbonylation fragments.

Ex Vivo Electrochemical pH Mapping of the Gastrointestinal Tract in the Absence and Presence of Pharmacological Agents.

Ex vivo pH profiling of the upper gastrointestinal (GI) tract (of a mouse), using an electrochemical pH probe, in both the absence and presence of pharmacological agents aimed at altering acid/bicarbonate production, is reported. Three pH electrodes were first assessed for suitability using a GI tract biological mimic buffer solution containing 0.5% mucin. These include a traditional glass pH probe, an iridium oxide (IrOx)-coated electrode (both operated potentiometrically), and a quinone (Q) surface-integrated boron-doped diamond (BDD-Q) electrode (voltammetric). In mucin, the time scale for both IrOx and glass to provide a representative pH reading was in the ∼100's of s, most likely due to mucin adsorption, in contrast to 6 s with the BDD-Q electrode. Both the glass and IrOx pH electrodes were also compromised on robustness due to fragility and delamination (IrOx) issues; contact with the GI tissue was an experimental requirement. BDD-Q was deemed the most appropriate. Ten measurements were made along the GI tract, esophagus (1), stomach (5), and duodenum (4). Under buffer only conditions, the BDD-Q probe tracked the pH from neutral in the esophagus to acidic in the stomach and rising to more alkaline in the duodenum. In the presence of omeprazole, a proton pump inhibitor, the body regions of the stomach exhibited elevated pH levels. Under melatonin treatment (a bicarbonate agonist and acid inhibitor), both the body of the stomach and the duodenum showed elevated pH levels. This study demonstrates the versatility of the BDD-Q pH electrode for real-time ex vivo biological tissue measurements.

A porous Cu(II)-based metal-organic framework carrier for pH-controlled anticancer drug delivery

A new metal-organic framework with suitable channel size and good stability in biological buffer solution was investigated to load 5-fluorouracil (5-FU) though a simple adsorption process. The successful loading of 5-Fu was confirmed by the gas sorption measurement and the loading capacity was characterized by UV–Vis spectroscopy, which reveal a drug loading of 37.22%. The drug delivery in the simulated cancerous tissues (pH = 5.8 and 6.8) exhibited a more progressive release in comparison with that in the normal tissues (pH = 7.4), demonstrating a physiological pH-responsive drug release. Furthermore, as demonstrated by the MTT assay, this drug/MOF composite shows low cytotoxicity, good biocompatibility, and anticancer activity against cell lines A549 and HeLa. The result shows that 1 could be taken as a potential drug carrier.

Selection of highly specific aptamers to Vibrio parahaemolyticus using cell-SELEX powered by functionalized graphene oxide and rolling circle amplification

Cell-SELEX is a powerful tool to screen aptamers binding to living cellular organisms such as bacteria, fungi and even oncocytes. Here, we developed an advanced cell-SELEX strategy featuring functionalized graphene oxide (GO) and isothermal rolling circle amplification (RCA) to select aptamers against a prevailing foodborne pathogen, Vibrio parahaemolyticus. Polyethyleneglycol (PEG) and chitosan (CTS) were grafted onto the sheet-like GO molecules to synthesize a PC-GO material. TEM and FT-IR characterization demonstrated that the PC-GO composites were near-nanometric scale and tethered with PEG and CTS moieties, a property that significantly improved its solubility in biological buffer solutions used in cell-SELEX process. PC-GO could bind with ssDNAs with lower affinities to target cells, therefore the selection efficiency is greatly enhanced. The cell-binding aptamer candidates (CACs) were amplified by 107 fold using complementary ring mediated (CRM-RCA), a created amplification method that generate single-stranded products, which could be directly used in the next round selection. As fueled by PC-GO and CRM-RCA, four highly specific aptamers with lowest Kd value of 10.3 ± 2.5 nM were obtained. Flow cytometry analysis showed that all the four aptamers exhibited more than 75% binding affinity to V. parahaemolyticus than to other foodborne bacteria (less than 18%). Simple procedure, high efficiency, and free from expensive thermal cycler (required by PCR amplification) will enable the established strategy to find its applications in aptamer selecting against fungi, stem and cancerous cells as well.

A low cytotoxic porous zinc-adeninate metal-organic framework carrier: pH-triggered drug release and anti-breast cancer study

In this study, a new zinc-based porous metal-organic framework (MOF) [Zn2(ad)2(hmdb)(H2O)](DMF)2(H2O) based on zinc(II) ions, biomolecular adenine (Had) and 4,4′-(hydroxymethylene)dibenzoic acid (H2hmdb) has been successfully prepared under solvothermal conditions. The X-ray study reveals that compound 1 belongs to the monoclinic space group C2/c and reveals a three-dimensional channel-type neutral framework. This MOF exhibits low toxicity by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium (MTT) assay. Due to its suitable channel size and good stability in biological buffer solution, the activated 1 has been used as a carrier for loading the anticancer drug 5-Fu (5-fluorouracil) though a simple adsorption process. The successful loading of 5-Fu was confirmed by the gas sorption measurement and the loading capacity was characterized by UV–Vis spectroscopy, which reveal a drug loading of 32.2 wt%. The drug delivery in the simulated cancerous tissues (pH = 5.0) exhibited a more effective release in comparison with that in the normal tissues (pH = 7.4), demonstrating a physiological pH-responsive drug release. Furthermore, in vitro cytotoxicity of 1 and 5-Fu loaded 1a was also evaluated using MTT assays against HepG2 and MCF-7 cells. A new zinc-based porous metal-organic framework (MOF) has been successfully prepared under solvothermal conditions. Due to its suitable channel size and good stability in biological buffers solution, compound 1 has been used as a carrier for loading the anticancer drug 5-Fu (5-fluorouracil) though a simple adsorption process. The drug-loaded MOF demonstrates a physiological pH-responsive drug release.

Ultrasensitive lateral-flow assays based on quantum dot encapsulations with signal amplification

Lateral-flow assays (LFAs), with its convenience and low cost, promise to become the in-home test format for early diagnosis and monitoring of tumor marker. However, the insufficient signal intensity was generated by signal reporters reducing the sensitivity of this format. In this study, a novel nanoscale signal reporter capable of amplifying the fluorescence signal is fabricated by encapsulating quantum dots (QDs) into modified tri-copolymer (poly(tert-butyl acrylate-co-ethyl acrylate-co-methacrylic acid)) (ODA-g-tri-copolymer). The amplified signal varied by simply adjusting the ratio of QDs to the ODA-g-tri-copolymer for obtaining QD nanospheres with high QD loading. They exhibits outstanding stability compared to the individual QDs both in the biological buffer and strong acid solutions. Here, human chorionic gonadotrophin (HCG) is employed as the model protein of LFAs. The results show that the detection limit of the QD nanospheres is pushed down to 0.016 IU/L, which is about ~ 38.5 times enhanced compared to the individual QD-based LFAs without any signal amplifying. The ultrasensitive LFAs were attributed to the signal amplification strategy, and their efficiency and robustness demonstrated the great potential in clinical applications.

Large Scale Screening of Southern African Plant Extracts for the Green Synthesis of Gold Nanoparticles Using Microtitre-Plate Method.

The preparation of gold nanoparticles (AuNPs) involves a variety of chemical and physical methods. These methods use toxic and environmentally harmful chemicals. Consequently, the synthesis of AuNPs using green chemistry has been under investigation to develop eco-friendly nanoparticles. One approach to achieve this is the use of plant-derived phytochemicals that are capable of reducing gold ions to produce AuNPs. The aim of this study was to implement a facile microtitre-plate method to screen a large number of aqueous plant extracts to determine the optimum concentration (OC) for the bio-synthesis of the AuNPs. Several AuNPs of different sizes and shapes were successfully synthesized and characterized from 17 South African plants. The characterization was done using Ultra Violet-Visible Spectroscopy, Dynamic Light Scattering, High Resolution Transmission Electron Microscopy and Energy-Dispersive X-ray Spectroscopy. We also studied the effects of temperature on the synthesis of the AuNPs and showed that changes in temperatures affect the size and dispersity of the generated AuNPs. We also evaluated the stability of the synthesized AuNPs and showed that some of them are stable in biological buffer solutions.

Online Miniaturized Asymmetrical Flow Field-Flow Fractionation and Inductively Coupled Plasma Mass Spectrometry for Metalloprotein Analysis of Plasma from Patients with Lung Cancer.

Metalloproteins (metal-binding proteins) refer to proteins containing metal ion cofactors. The importance of these proteins has increased owing to their involvement in many biological processes. Here, we introduce an analytical platform based on online coupling of miniaturized asymmetrical flow field-flow fractionation (mAF4) and inductively coupled plasma mass spectrometry (ICPMS) for size separation of proteins followed by the detection of metals associated with plasma metalloproteins. Not only did the mild separation of mAF4 get carried out in a biological buffer solution to minimize disruption of the metal-complex structure but free metal ions and salts from complicated biological samples were also removed during separation by crossflow. The relative quantities of metalloproteins detected by mAF4-ICPMS between plasma samples from patients with lung cancer and healthy controls were compared by determining the peak areas of detected elements and retention times; among these, 7 (55Mn, 60Ni, 63Cu, 66Zn, 90Zr, 127I, and 137Ba) out of 16 elements showed substantial changes in patients with lung cancer. For the quantitative comparison of metalloproteins, protein fractions during mAF4 were collected and analyzed by nanoflow liquid chromatography-tandem mass spectrometry using isotope-coded carbamidomethylation. Quantitative analysis showed that some metalloproteins associated with 55Mn, 60Ni, 63Cu, and 66Zn exhibited changes similar to those in patients. These findings demonstrated the potential of mAF4-ICPMS as a powerful high-speed screening method for targeted metalloproteins related to diseases.

Modulating antibacterial immunity via bacterial membrane-coated nanoparticles.

Synthetic nanoparticles coated with cellular membranes have been increasingly explored to harness natural cell functions toward the development of novel therapeutic strategies. Herein, we report on a unique bacterial membrane-coated nanoparticle system as a new and exciting antibacterial vaccine. Using Escherichia coli as a model pathogen, we collect bacterial outer membrane vesicles (OMVs) and successfully coat them onto small gold nanoparticles (AuNPs) with a diameter of 30 nm. The resulting bacterial membrane-coated AuNPs (BM-AuNPs) show markedly enhanced stability in biological buffer solutions. When injected subcutaneously, the BM-AuNPs induce rapid activation and maturation of dendritic cells in the lymph nodes of the vaccinated mice. In addition, vaccination with BM-AuNPs generates antibody responses that are durable and of higher avidity than those elicited by OMVs only. The BM-AuNPs also induce an elevated production of interferon gamma (INFγ) and interleukin-17 (IL-17), but not interleukin-4 (IL-4), indicating its capability of generating strong Th1 and Th17 biased cell responses against the source bacteria. These observed results demonstrate that using natural bacterial membranes to coat synthetic nanoparticles holds great promise for designing effective antibacterial vaccines.

Optimizing Au/Ag core–shell nanorods: purification, stability, and surface modification

The purification, stability, and surface modification of Au/Ag core–shell nanorods (Au/Ag NRs) in a biological buffer solution were systematically studied for the first time. In this study, Au/Ag NRs were synthesized by chemically reducing silver on the surface of gold nanorods using cetyltrimethylammonium bromide as surfactant and then purified by centrifugation washing. Based on the analysis of UV–Vis absorption spectra, TEM images, Raman spectra, and the ξ-potential, it was observed that after the second washing step, the Au/Ag NRs displayed good stability and high surface-enhanced Raman scattering (SERS) enhancement. When the as-prepared Au/Ag NRs were centrifuged more than twice, a structural transition in the surfactant layer was manifested with a sudden increase in the Raman signal intensities at 760 and 1,455 cm−1. Moreover, 4-mercaptobenzoic acid (4MBA) was used as a Raman reporter molecule to investigate the SERS characteristics of the purified Au/Ag NRs. The Raman signal intensity was enhanced with increasing the concentration of 4MBA and reached its highest intensity at the saturation concentration of 1.0 µM 4MBA in a 5 ml solution of the purified Au/Ag NRs. To prevent significant aggregation of the 4MBA-tagged Au/Ag NRs, a poly(styrenesulfonate) (PSS) layer was assembled on the nanorod surfaces by electrostatic adsorption for further surface modification, which made the 4MBA-tagged Au/Ag NRs suitable for the labeled biosensing. Subsequently, the characteristics of the PSS-coated Au/Ag NRs were demonstrated for the potential applications of label-free biosensing.

Light-triggered carbon monoxide delivery with Al-MCM-41-based nanoparticles bearing a designed manganese carbonyl complex.

A photoactive manganese carbonyl complex namely, fac-[Mn(pqa)(CO)3]ClO4 (abbreviated as {Mn-CO}, pqa = (2-pyridylmethyl)(2-quinolylmethyl)amine) has been incorporated in the pores of 60 nm mesoporous Al-MCM-41 nanoparticles. Strong electrostatic interactions with the negatively charged walls of the aluminosilicate host entrap the cationic carbonyl complex in the resulting material {Mn-CO}@Al-MCM-41 which has been characterized by various physical techniques and chemical analysis. The sample morphology and microstructure of the material have been established by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results of powder X-ray diffraction (PXRD) data and the SEM-EDX elemental maps of Si, O, Al and Mn confirm that the carbonyl complex is within the pores of the nanoparticles. The 2% manganese content of {Mn-CO}@Al-MCM-41, determined by acid digestion followed by inductively coupled plasma-optical emission spectroscopy (ICP-OES), indicates efficient loading of the carbonyl complex in the nanoparticles. In biological buffer solutions, less than 2% leaching of {Mn-CO} from the nanoparticles was noted within a period of 24 h. When exposed to a broadband visible light source (λ > 350 nm), {Mn-CO}@Al-MCM-41 rapidly releases CO, as confirmed by the reduced myoglobin assay. The utility of light-induced CO delivery by {Mn-CO}@Al-MCM-41 has been established by its capacity to relax rat aorta muscle rings in tissue bath experiments.

Spatial Distribution of Lipid Headgroups and Water Molecules at Membrane/Water Interfaces Visualized by Three-Dimensional Scanning Force Microscopy

At biological interfaces, flexible surface structures and mobile water interact with each other to present non-uniform three-dimensional (3D) distributions. In spite of their impact on biological functions, molecular-scale understanding of such phenomena has remained elusive. Here we show direct visualization of such interfacial structures with subnanometer-scale resolution by 3D scanning force microscopy (3D-SFM). We measured a 3D force distribution at an interface between a model biological membrane and buffer solution by scanning a sharp tip within the 3D interfacial space. We found that vertical cross sections of the 3D image taken along a specific lateral direction show characteristic molecular-scale contrasts tilted at 30° to the membrane surface. Detailed analysis of the 3D image reveals that the tilted contrast corresponds to the time-averaged conformation of fluctuating lipid headgroups. On the basis of the obtained results, we discuss the relationships among the hydration structure, headgroup fluctuation, molecular fluidity, and mechanical strength of the membrane. The results demonstrate that 3D-SFM is capable of visualizing averaged 3D distribution of fluctuating surface structures as well as that of mobile water (i.e., hydration structure) at interfaces between biological systems and water.

Electrically Addressed Dual Resonator Sensing Platform for Biochemical Detection

Chemically functionalized silicon microresonators provide the potential for sensitive, label-free biomolecular detection by coupling small induced perturbations in stiffness, mass, and dissipation due to surface bound analyte to their measured frequency response. However, several implementation challenges arise from the necessity of operation in compatible biological buffer solutions. These challenges include minimizing undesired effects of fluid-structure interaction and buffer interference with signal transduction. In this paper, we present a novel dual resonator sensing platform (DRP) to address these challenges, wherein electrical transduction and biochemical sensing are spatially separated onto two different mechanically coupled resonators. This enables electrical interrogation of the sensor without compromising the sensing environment, allowing for relative ease of fabrication and the possibility of integration with on-chip electronics. We demonstrate the functionality of the DRP as a mass sensing platform, with a mass responsivity of 34 Hz/ng in air. The viscous effects on dynamic response of the DRP were investigated by comparing the measurements with theoretical values, and a quality factor of 221 in water is demonstrated. Furthermore, characterization of the DRP was preformed with streptavidin-coated microbeads, and the measured response is in close agreement with the model. Finally, the use of DRP for measurement of dried cell mass and accurate cell counting is demonstrated with a detection limit of 1.46 ng.

Hybrid, Silica-Coated, Janus-Like Plasmonic-Magnetic Nanoparticles

Hybrid plasmonic-magnetic nanoparticles possess properties that are attractive in bioimaging, targeted drug delivery, in vivo diagnosis and therapy. The stability and toxicity, however, of such nanoparticles challenge their safe use today. Here, biocompatible, SiO2-coated, Janus-like Ag/Fe2O3 nanoparticles are prepared by one-step, scalable flame aerosol technology. A nanothin SiO2 shell around these multifunctional nanoparticles leaves intact their morphology, magnetic and plasmonic properties but minimizes the release of toxic Ag+ ions from the nanosilver surface and its direct contact with live cells. Furthermore, this silica shell hinders flocculation and allows for easy dispersion of such nanoparticles in aqueous and biological buffer (PBS) solutions without any extra functionalization step. As a result, these hybrid particles exhibited no cytotoxicity during bioimaging and remained stable in suspension with no signs of agglomeration and sedimentation or settling. Their performance as biomarkers was explored by selectively binding them with live tagged Raji and HeLa cells enabling their detection under dark-filed illumination. Therefore, these SiO2-coated Ag/Fe2O3 nanoparticles do not exhibit the limiting physical properties of each individual component but retain their desired functionalities facilitating thus, the safe use of such hybrid nanoparticles in bio-applications.