Zihnil Adha Islamy Mazrad

Rapid fluorometric bacteria detection assay and photothermal effect by fluorescent polymer of coated surfaces and aqueous state

A fluorescent dye and a photothermal agent were grafted onto a cationic polymer for rapid and simple bacteria detection in liquid and solid phase based fluorescence on/off. The integrated poly(vinylpyrrolidone) (PVP) backbone with catechol and bromoethane moieties possesses unique optical properties due to the presence of boron dipyrromethane (BODIPY) and near infared NIR-responsive IR825 (F-PVP). The cationic segments showed distinct fluorescence quenching patterns after interaction with gram-positive and gram-negative bacteria via polyion complex interactions. Fluorescence quenching depended on direct interaction of the bacterial cell membrane, as confirmed using SEM and confocal imaging. The detection limit was 1mg/mL for the liquid-phase assay and the minimal detectable concentration of bacteria using the solid-phase assay was 106CFU/mL. After bacterial detection in contaminated area, our system can directly kill bacteria via the photothermal conversion ability of the IR825 substituent using NIR exposure by polymer solution and limited in coated PP. Finally, the proposed biosensor is capable as potential material for detection of bacteria in simple liquid and solid phase assay.

Design of Surface-Coatable NIR-Responsive Fluorescent Nanoparticles with PEI Passivation for Bacterial Detection and Killing

The ability to quickly detect and kill bacteria is crucial in the realm of antibiotic resistance. In this study, we synthesized a detection probe consisting of polyethylenimine (PEI)-passivated polydopamine-based fluorescent carbon (FDA:PEI) nanoparticles, generating a cationic adhesive material for bacterial detection that is surface-coatable, photothermal, and antibacterial. The cationic FDA:PEI nanoparticles effectively bound to the anionic bacterial cell wall, resulting in a dramatic quenching effect visible in fluorescence spectra and confocal images. In this fluorescence on/off system, FDA:PEI nanoparticles showed similar bacterial detection abilities between aqueous- and solid-phase assays. Scanning electron microscopy clearly showed the attachment of FDA:PEI nanoparticles to the surface of bacteria, both in solution and as a coating on the surface of a polypropylene film. In addition to detection, this versatile material was found to have an antibacterial potential, via near-infrared irradiation to induce a heat release, killing bacteria by thermolysis. Thus, by exploiting the cationic and catechol moieties on the surface of polydopamine carbon dots, we developed a novel bacterial-detection platform that can be used in a broad range of conditions.

Progress in internal/external stimuli responsive fluorescent carbon nanoparticles for theranostic and sensing applications

In the past decade, fluorescent carbon nanoparticles (FNPs) prepared from natural resources and biomaterials have been attractive due to their various properties, such as unique optical properties, great biocompatibility, water dispersion, and facile surface functionalization. Depending on the properties of the carbon sources and the subsequent carbonization processes, internal/external stimuli responsive carbon nanoparticles have been generated that are useful for theranostic and sensing applications. In this review, we highlight the recent developments in the use of FNPs in nanomedicine in great detail, particularly for FNPs responding to internal stimuli, including redox, pH, and enzymes, and external stimuli, including temperature, light, and magnetic fields, for drug delivery and sensing applications. Furthermore, we hope to provide insight that could stimulate further research aiming for unparalleled useful applications. As a result, there are many possibilities that can be explored from this smart material.

pH-switchable bacteria detection using zwitterionic fluorescent polymer

A zwitterionic fluorescent polymer with high sensitivity to pH changes was constructed for the detection and imaging of both gram-positive and gram-negative pathogenic bacteria. A detection probe using the zwitterionic fluorescent polymer was synthesized with single boron dipyrromethane (BODIPY) as a hydrophobic dye and bromoethane as a cationic group for bacteria binding with conjugated poly(sulfobetaine methacrylate) (BOD/BE-PSM). The zwitterionic fluorescent polymer bound to bacteria through ionic complexes between anionic groups on the bacterial surface and cationic BOD/BE-PSM groups after 1h incubation. This finding demonstrated that the fluorescence on/off system operated via changes in the hydrophilic and hydrophobic nature of the zwitterionic fluorescent polymer, depending on the pH (6.0, 7.4, or 9.0), at a fixed 1mg/mL polymer concentration. The system showed good stability with a limit of detection of 1mg/mL. Quenching caused by interactions with the hydrophobic BODIPY dye was also observed, enabling bacteria detection, as shown by fluorescence spectroscopy and confocal microscopy images. Our results indicated that the zwitterionic fluorescent polymer could be used to detect bacteria over a wide range of pH values.

Target-specific induced hyaluronic acid decorated silica fluorescent nanoparticles@polyaniline for bio-imaging guided near-infrared photothermal therapy

We describe a novel synthesis method for silica nanoparticles, which involves a combination of these nanoparticles with targetable and nontargetable fluorescent dopamine-conjugated hyaluronic acid (HA-DA) via rational chemical dehydration. The resulting HA-decorated silica fluorescent nanoparticles, electrostatically linked to polyaniline (PANI) to form ionic complexes, possessed high fluorescence intensity and were monodisperse in solution, near-infrared light responsive, and amenable to specific labeling of cancer cell lines. When exposed to near-infrared irradiation, the fluorescent silica nanoparticles exerted photothermal cytotoxicity guided by bioimaging and distinguished malignant cancer cells from normal cells via receptor CD44. Different heating properties of nanoparticles depend on local interactions between different structures, and determination of their efficacy could lead to new thermal treatment options such as noninvasive photothermal therapy.

Determination of Cancer Cell-Based pH-Sensitive Fluorescent Carbon Nanoparticles of Cross-Linked Polydopamine by Fluorescence Sensing of Alkaline Phosphatase Activity on Coated Surfaces and Aqueous Solution

The tumor-specific sensitive fluorescence sensing of cellular alkaline phosphatase (ALP) activity on the basis of host-guest specific and pH sensitivity was conducted on coated surfaces and aqueous states. Cross-linked fluorescent nanoparticles (C-FNP) consisting of β-cyclodextrin (β-CD)/boronic acid (BA) and fluorescent hyaluronic acid [FNP(HA)] were conjugated to fluorescent polydopamine [FNP(pDA)]. To determine the quenching effect of this system, hydrolysis of 4-nitrophenyl phosphate (NPP) to 4-nitrophenol (NP) was performed in the cavity of β-CD in the presence of ALP activated photoinduced electron transfer (PET) between NP and C-FNP. At an ALP level of 30-1000 U/L, NP caused off-emission of C-FNP because of their specific host-guest recognition. Fluorescence can be recovered under pH shock due to cleavage of the diol bond between β-CD and BA, resulting in release of NP from the fluorescent system. Sensitivity of the assays was assessed by confocal imaging not only in aqueous states, but also for the first time on coated surfaces in MDAMB-231 and MDCK cells. This novel system demonstrated high sensitivity to ALP through generation of good electron donor/acceptor pair during the PET process. Therefore, this fluorescence sensor system can be used to enhance ALP monitoring and cancer diagnosis on both coated surfaces and in aqueous states in clinical settings.

Boronate-based fluorescent carbon dot for rapid and selectively bacterial sensing by luminescence off/on system

Graphical abstract Figure. No caption available. HighlightsDye conjugated to phenylboronic acid‐functionalized fluorescent carbon dots.Fluorescent quenching system allows bacteria detector based switching off‐on behavior.High sensitivity and selectivity with diol‐containing glucose on bacterial surface.Cheap and high affinity to detect chemoselective ligand‐based real‐environments. ABSTRACT Boronic acid, which can bind chemo‐selectively and reversibly to diols, could be used for the early detection of bacteria through its affinity‐binding reaction with diol groups on the bacterial cell wall. Herein, we describe the use of a diol‐modified fluorescent probe (DYE) conjugated to a nanosensor consisting of phenylboronic acid‐functionalized fluorescent carbon dot (FCD) to allow quenching via the Förster resonance energy transfer (FRET) process. Phenylboronic acid is well‐known for its preferential affinity for diol‐containing molecules through cyclic ester bond formation. Therefore, in the presence of glucose‐containing bacteria, the DYE in the cyclic ester form will be released from the FCD and replaced by the bacterial cell forming a new cyclic boronate ester bond with the nanoparticle, inducing recovery of the fluorescence. Quantitatively, the systems detection performance at various bacterial concentrations (101–107 CFU/mL) reached ˜100% after 60 min, indicating that the high binding affinity of the diol moeity on the peptidoglycan (sugar)‐rich bacteria was enough to displace the DYE from the boronic acid‐functionalized FCD platform. Our facile and tunable fluorescence switch‐on system was tested for its ability to detect bacteria in water from a contaminated river. Incredibly, the system was most successful in detecting bacteria in the contaminated river water, thus proving it to be a less expensive and more robust affinity biosensor for the detection of contaminating pathogens in various chemoselective ligand‐based environments.

Membrane and nucleus targeting for highly sensitive cancer cell detection using pyrophosphate and alkaline phosphatase activity-mediated fluorescence switching of functionalized carbon dots

A specific membrane and nucleus targeted fluorescence OFF-ON-OFF system, using the dodecane/sulfobetaine group of functionalized carbon dots (CD) with a copper ion (Cu2+-CD) based on the presence of pyrophosphate (PPi) molecules and alkaline phosphatase (ALP) activity, for cancer cell detection was designed. The biosensor could be effectively transported from the cytosol to the nucleus in MDAMB cells, but not in MDCK cells due to the response to a change in pH by CD functionalized with zwitterionic groups. The biosensor also showed a membrane-selective regulated route for fusion of long alkyl chain grafted-CD on cell membranes. As a potential sensor, the fluorescence of the prepared Cu2+-CD was significantly quenched due to aggregation. In human cancer MDAMB cells, a nearly complete restoration of the fluorescence intensity of the Cu2+-CD was observed because of the high levels of intracellular PPi, which preferentially bound to Cu2+. After 10 min, in the MDAMB cells, re-quenching of the CD fluorescence occurred because of the high level of intracellular ALP, which can hydrolyze PPi and release the Cu2+ to re-aggregate the CD. In contrast to MDAMB cells, MDCK cells did not show an obvious response to the specific intracellular biomolecules, thus, enabling the biosensor to be used to distinguish between cancer and normal cells. In conclusion, this biosensor has the potential to be a simple and sensitive cancer diagnostic tool that can differentiate normal cells from cancer cells on coated surfaces and in aqueous states.

Synthesis of catechol-functionalized polymer–based crosslinked thermoresponsive hydrogels for tissue-adhesive material:

Injectable and temperature-sensitive hydrogels were synthesized for use as a tissue-adhesive material between dopamine end-capped Pluronic and CCDP-q-PDB (2-chloro-3′,4′-dihydroxyacetophenone-quaternized poly((dimethyl aminoethyl methacrylate)-co-(t-butylmethacrylate))). The mixture of dopamine end-capped Pluronic and CCDP-q-PDB exists in a viscous solution state at room temperature, but becomes a gel via in situ crosslinking at body temperature. The hydrogel structure was shown to be more stable than Pluronic F127 copolymers in aqueous solution. At a 14:8 wt% ratio of dopamine end-capped Pluronic to CCDP-q-PDB, the sol quickly transformed into a gel at body temperature and under physiological conditions (<10 s), showing excellent gel stability. To evaluate the tissue-adhesive properties, the temperature-sensitive crosslinked dopamine end-capped Pluronic CCDP-q-PDB hydrogels, which can be applied for drug delivery, tissue engineering, and for use as tissue adhesives, were tested using a universal testing machine.

Redox-responsive FRET-based polymer dot with BODIPY for fluorescence imaging-guided chemotherapy of tumor

Graphical abstract Figure. No Caption available. Abstract Redox‐responsive polymer dot (PD) were synthesized from disulfide cross‐linked polymers in a carbonized process to allow quenching effects by loading of boron‐dipyrromethene (BODIPY) onto the matrix. The disulfide linkage facilitated degradation of the PD system by intracellular glutathione (GSH), leading to fluorescence recovery by BODIPY and intracellular drug release. The paclitaxel release profile showed that approximately 100% of the drug escaped from the matrix in response to 10 mM GSH, whereas less than 10% was released in the absence of GSH. In vitro studies showed that quenching produced by BODIPY loading enabled visual monitoring of cancer cell death, as the quenching disappeared when BODIPY was released by GSH inside of cancer cells. The PD contain disulfide bonds representing a GSH‐triggered ligand; thus, nanocarriers presented enhanced in vivo chemotherapeutic inhibition in xenograft tumor‐bearing mice localized at the cancer location, guided by fluorescent off‐on system tracking and measured by the release of BODIPY. This platform reacts to the redox level in sensitive manner and cancer cell death can be monitored by fluorescence, making this platform useful for bio‐applications, particularly in vitro and in vivo therapy and diagnosis, while considering the cell physiological environment. This system may be useful for wider medical applications.