Synthesis of functionalized mesoporous silica nanoparticles for colorimetric and fluorescence sensing of selective metal (Fe3+) ions in aqueous solution

The fabrication of red fluorescent hybrid mesoporous silica-based nanosensor materials has promised the bioimaging and selective detection of toxic pollutants in aqueous solutions. In this study, we present a hybrid mesoporous silica nanosensor in which the propidium iodide (PI) was used to conveniently integrate into the mesopore walls using bis(trimethoxysilylpropyl silane) precursors. Various characterization techniques including X-ray diffraction (XRD), Fourier-transform infrared (FTIR), N2 adsorption-desorption, zeta potential, particle size analysis, thermogravimetric, and UV-visible analysis were used to analyze the prepared materials. The prepared PI integrated mesoporous silica nanoparticles (PI-MSNs) selective metal ion sensing capabilities were tested with a variety of heavy metal ions (100 mM), including Ni2+, Cd2+, Co2+, Zn2+, Cr3+, Cu2+, Al3+, Mg2+, Hg2+ and Fe3+ ions. Among the investigated metal ions, the prepared PI-MSNs demonstrated selective monitoring of Fe3+ ions with a significant visible colorimetric pink color change into orange and quenching of pink fluorescence in an aqueous suspension. The selective sensing behavior of PI-MSNs might be due to the interaction of Fe3+ ions with the integrated PI functional fluorophore present in the mesopore walls. Therefore, we emphasize that the prepared PI-MSNs could be efficient for selective monitoring of Fe3+ ions in an aqueous solution and in the biological cellular microenvironment.

Mesoporous Silica-Layered Gold Nanorod Core@Silver Shell Nanostructures for Intracellular SERS Imaging and Phototherapy

Precision diagnosis-guided efficient treatment is crucial to extending the lives of cancer patients. The integration of surface-enhanced Raman scattering (SERS) imaging and phototherapy into a single nanoplatform has been considered a more accurate diagnosis and treatment strategy for cancer nanotheranostics. Herein, we constructed a new type of mesoporous silica-layered gold nanorod core@silver shell nanostructures loaded with methylene blue (GNR@Ag@mSiO2-MB) as a multifunctional nanotheranostic agent for intracellular SERS imaging and phototherapy. The synthesized GNR@Ag@mSiO2-MB nanostructures possessed a uniform core-shell structure, strong near-infrared (NIR) absorbance, photothermal conversion efficiency (65%), dye loading ability, SERS signal, and Raman stability under phototherapy conditions. Under single 785 nm NIR laser irradiation, the intracellular GNR@Ag@mSiO2-MB nanostructures were dramatically decreased to <9%, which showed excellent photothermal and photodynamic effects toward cancer cell killing, indicating that the combination of photothermal therapy (PTT) and photodynamic therapy (PDT) of the GNR@Ag@mSiO2-MB nanostructures could greatly enhance the therapeutic efficacy of cancer cell death. GNR@Ag@mSiO2-MB nanostructures demonstrated a strong Raman signal at 450 and 502 cm-1, corresponding to the δ(C-N-C) mode, suggesting that the Raman bands of GNR@Ag@mSiO2-MB nanostructures were more efficient to detect CT-26 cell SERS imaging with high specificity. Our results indicate that GNR@Ag@mSiO2-MB nanostructures offer an excellent multifunctional nanotheranostic platform for SERS imaging and synergistic anticancer phototherapy in the future.

Arrhythmic Effects Evaluated on Caenorhabditis elegans: The Case of Polypyrrole Nanoparticles

Experimental studies and clinical trials of nanoparticles for treating diseases are increasing continuously. However, the reach to the market does not correlate with these efforts due to the enormous cost, several years of development, and off-target effects like cardiotoxicity. Multicellular organisms such as the Caenorhabditis elegans (C. elegans) can bridge the gap between in vitro and vertebrate testing as they can provide extensive information on systemic toxicity and specific harmful effects through facile experimentation following 3R EU directives on animal use. Since the nematodes' pharynx shares similarities with the human heart, we assessed the general and pharyngeal effects of drugs and polypyrrole nanoparticles (Ppy NPs) using C. elegans. The evaluation of FDA-approved drugs, such as Propranolol and Racepinephrine reproduced the arrhythmic behavior reported in humans and supported the use of this small animal model. Consequently, Ppy NPs were evaluated due to their research interest in cardiac arrhythmia treatments. The NPs' biocompatibility was confirmed by assessing survival, growth and development, reproduction, and transgenerational toxicity in C. elegans. Interestingly, the NPs increased the pharyngeal pumping rate of C. elegans in two slow-pumping mutant strains, JD21 and DA464. Moreover, the NPs increased the pumping rate over time, which sustained up to a day post-excretion. By measuring pharyngeal calcium levels, we found that the impact of Ppy NPs on the pumping rate could be mediated through calcium signaling. Thus, evaluating arrhythmic effects in C. elegans offers a simple system to test drugs and nanoparticles, as elucidated through Ppy NPs.

Cold plasma-assisted regeneration of biochar for dye adsorption

Environmental remedies, including adsorption-based water purification, are now being asked to meet the requirement for a low-carbon circular economy requiring low energy and low material consumption. In this regard, we tested the possibility of regenerating adsorbents via cold plasma (CP) treatment for less use of adsorbents and no washing solution. In the adsorption of methylene blue (MB) using carbonized rice husk (CRH) and five successive regeneration cycles by CP treatment, the removal efficiencies were maintained at a moderate level (∼70% of the initial performance), unlike five consecutive adsorption without CP treatment (∼9-13% of the initial performance). The regeneration of CRH by CP treatment was also double-checked by the FESEM, EDS, BET, FTIR, XPS, and surface zeta potential measurements. The successfully recovered adsorption capability is related to the remediation of adsorption sites. It is also worth noting that the required power consumption for recycling by CP treatment was about 6.4 times lower than carbonizing new rice husks. This work provides insights into recovering adsorbents using CP without rigorous, costly, and energy-intensive processes.

Looking deep inside tissue with photoacoustic molecular probes: a review

Significance

Deep tissue noninvasive high-resolution imaging with light is challenging due to the high degree of light absorption and scattering in biological tissue. Photoacoustic imaging (PAI) can overcome some of the challenges of pure optical or ultrasound imaging to provide high-resolution deep tissue imaging. However, label-free PAI signals from light absorbing chromophores within the tissue are nonspecific. The use of exogeneous contrast agents (probes) not only enhances the imaging contrast (and imaging depth) but also increases the specificity of PAI by binding only to targeted molecules and often providing signals distinct from the background.

Aim

We aim to review the current development and future progression of photoacoustic molecular probes/contrast agents.

Approach

First, PAI and the need for using contrast agents are briefly introduced. Then, the recent development of contrast agents in terms of materials used to construct them is discussed. Then, various probes are discussed based on targeting mechanisms, in vivo molecular imaging applications, multimodal uses, and use in theranostic applications.

Results

Material combinations are being used to develop highly specific contrast agents. In addition to passive accumulation, probes utilizing activation mechanisms show promise for greater controllability. Several probes also enable concurrent multimodal use with fluorescence, ultrasound, Raman, magnetic resonance imaging, and computed tomography. Finally, targeted probes are also shown to aid localized and molecularly specific photo-induced therapy.

Conclusions

The development of contrast agents provides a promising prospect for increased contrast, higher imaging depth, and molecularly specific information. Of note are agents that allow for controlled activation, explore other optical windows, and enable multimodal use to overcome some of the shortcomings of label-free PAI.

Tumor acidity-activatable photothermal/Fenton nanoagent for synergistic therapy

Intracellular formation of therapeutic agents has become one of the effective ways for cancer-specific treatment. Herein, a tumor acidity-activatable photothermal/Fenton nanoagent (denoted as CoPy) was constructed based on oxidized zeolitic imidazolate framework-67 (oxZIF-67) nanosheet and pyrrole (Py) monomer for synergistic therapy. The CoPy showed negligible toxicity to normal cell models RAW264.7 and 3T3 cell lines, and could be degraded by ascorbic acid in normal physiological conditions. However, once uptaken by 4T1 cells, the acidic pH led to the release of Co³⁺, which served as a strong oxidant to induce the polymerization of Py to form polypyrrole (PPy) for site-specific photothermal therapy (PTT). Most appealingly, the PPy could chelate the generated Co²⁺ in the polymerization process to initiate the Fenton-like reaction, which was more capable to produce highly toxic hydroxyl radical (•OH) for chemodynamic therapy (CDT) compared to the free Co²⁺ ones. In vitro and in vivo experiments demonstrated that all functionalities on CoPy worked collaboratively, and 78% of tumors were inhibited through cooperative PTT/CDT. Such a novel therapeutic nanoagent with tumor selectivity opens new opportunities for combinational treatment paradigms.

PLGA-coated methylene blue nanoparticles for photoacoustic imaging and photodynamic/photothermal cascaded precisely synergistic therapy of tumor

Photodynamic therapy (PDT) and photothermal therapy (PTT) are synergetic treatment strategies in antitumor treatment to achieve the best anticancer efficacy. Although traditional photosensitizer materials such as methylene blue (MB) have been widely studied for PDT, the photothermal effect is rarely reported. Herein, mono-component nanoparticles lactic-co-glycolic acid-coated methylene blue (MBNPs) based on methylene blue (MB) and lactic-co-glycolic acid (PLGA) were prepared by a facile solution-based emulsification method at room temperature. The resulting nanoparticles possess high photothermal conversion efficiency and excellent photodynamic effect. For the first time, the in vitro and in vivo tests indicated an enhanced antitumor efficacy for MBNPs with combined PDT and PTT. This study provides an efficient approach to fabricate nano-MB and also demonstrates the great potential of lactic-co-glycolic acid-coated MB for biomedical applications. Most importantly, the strong tumor growth inhibition by synergistic PTT and PDT demonstrates an excellent cascaded synergistic effect of MBNPs for the tumor therapy.

Evaluation of Electrochromic Properties of Polypyrrole/Poly(Methylene Blue) Layer Doped by Polysaccharides

Polypyrrole (Ppy) and poly(methylene blue) (PMB) heterostructure (Ppy-PMB) was electrochemically formed on the indium tin oxide (ITO) coated glass slides, which served as working electrodes. For electropolymerization, a solution containing pyrrole, methylene blue, and a saccharide (lactose, sucrose, or heparin) that served as dopant was used. The aim of this study was to compare the effect of the saccharides (lactose, sucrose, and heparin) on the electrochromic properties of the Ppy-PMB layer. AFM and SEM have been used for the analysis of the surface dominant features of the Ppy-PMB layers. From these images, it was concluded that the saccharides used in this study have a moderate effect on the surface morphology. Electrochromic properties were analyzed with respect to the changes of absorbance of the layer at two wavelengths (668 nm and 750 nm) by changing the pH of the surrounding solution and the potential between +0.8 V and -0.8 V. It was demonstrated that the highest absorbance changes are characteristic for all layers in the acidic media. Meanwhile, the absorbance changes of the layers were decreased in the more alkaline media. It was determined that the Ppy-PMB layers with heparin as a dopant were more mechanically stable in comparison to the layers doped with lactose and sucrose. Therefore, the Ppy-PMB layer doped with heparin was selected for the further experiment and it was applied in the design of electrochromic sensors for the determination of three xanthine derivatives: caffeine, theobromine, and theophylline. A linear relationship of ΔA (∆A = A_+0.8V - A_-0.8V) vs. concentration was determined for all three xanthine derivatives studied. The largest change in optical absorption was observed in the case of theophylline determination.

Keratin-Based Nanoparticles with Tumor-Targeting and Cascade Catalytic Capabilities for the Combinational Oxidation Phototherapy of Breast Cancer

Photodynamic therapy (PDT) holds tantalizing prospects of a prominent cancer treatment strategy. However, its efficacy remains limited by virtue of the hypoxic tumor microenvironment and the inadequate tumor-targeted delivery of photosensitizers, and these can be further exacerbated by the lack of development of a well-controlled nitric oxide (NO) release system at the target site. Inspired by Chinese medicine, we propose a revealing new keratin application. Keratin has garnered attention as an NO generator; however, its oncological use has rarely been investigated. We hypothesized that the incorporation of a phenylboronic acid (PBA) targeting ligand/methylene blue (MB) photosensitizer with a keratin NO donor would facilitate precise tumor delivery, enhancing PDT. Herein, we demonstrated that MB@keratin/PBA/d-α-tocopherol polyethylene glycol 1000 succinate (TPGS) nanoparticles (MB@KPTNPs) specifically targeted breast cancer cells and effectively suppressed their growth. Through MB-mediated biometabolism, the endocytic MB@KPTNPs produced a sufficient amount of intracellular NO that reduced the glutathione level while boosting the efficiency of PDT. A therapeutic combination of NO/PDT was therefore achieved, resulting in significant inhibition of both in vivo tumor growth and lung metastasis. These findings underscore the importance of utilizing keratin-based nanoparticles that simultaneously combine targeting of the tumor and self-generating NO with a cascading catalytic ability as a novel oxidation therapeutic strategy for enhancing PDT.

Fluorescence/photoacoustic imaging-guided nanomaterials for highly efficient cancer theragnostic agent

Imaging modalities combined with a multimodal nanocomposite contrast agent hold great potential for significant contributions in the biomedical field. Among modern imaging techniques, photoacoustic (PA) and fluorescence (FL) imaging gained much attention due to their non-invasive feature and the mutually supportive characteristic in terms of spatial resolution, penetration depth, imaging sensitivity, and speed. In this present study, we synthesized IR783 conjugated chitosan-polypyrrole nanocomposites (IR-CS-PPy NCs) as a theragnostic agent used for FL/PA dual-modal imaging. A customized FL and photoacoustic imaging system was constructed to perform required imaging experiments and create high-contrast images. The proposed nanocomposites were confirmed to have great biosafety, essentially a near-infrared (NIR) absorbance property with enhanced photostability. The in vitro photothermal results indicate the high-efficiency MDA-MB-231 breast cancer cell ablation ability of IR-CS-PPy NCs under 808 nm NIR laser irradiation. The in vivo PTT study revealed the complete destruction of the tumor tissues with IR-CS-PPy NCs without further recurrence. The in vitro and in vivo results suggest that the demonstrated nanocomposites, together with the proposed imaging systems could be an effective theragnostic agent for imaging-guided cancer treatment.

MnO2 nanosheets anchored with polypyrrole nanoparticles as a multifunctional platform for combined photothermal/photodynamic therapy of tumors

Herein, PPy@MnO₂ nanocomposites were first harvested by anchoring MnO₂ nanosheets on polypyrrole (PPy) nanoparticles via an in situ redox reaction, then polyethylene glycol (PEG) modifier and methylene blue (MB) photosensitizer were linked through electrostatic interactions to obtain PPy@MnO₂-PEG-MB nanoarchitectures. PPy nanoparticles ensure photothermal therapy (PTT) ability and MnO₂ nanosheets ameliorate tumor hypoxia for enhanced photodynamic therapy (PDT). Therefore, a multifunctional nanotherapeutic system was constructed for the combined PTT/PDT of tumors. For extracellular photothermal properties, the optimal temperature elevation was 52.6 °C with 54.4% photothermal conversion efficiency. The extracellular PDT ability was measured by detecting ¹O₂ generation; more ¹O₂ was produced under acidic conditions in the presence of H₂O₂ (a simulated tumor microenvironment). The effective cellular uptake of the nanotherapeutic system in HeLa cells was observed by confocal laser scanning microscopy (CLSM). CLSM also indicated that more ¹O₂ was generated by the nanotherapeutic system as compared to free MB in HeLa cells, confirming the amelioration of tumor hypoxia by MnO₂ nanosheets. MTT assays demonstrated that the nanotherapeutic system possessed superior biocompatibility without laser irradiation, and the lowest cell viabilities for single PTT and PDT groups were 13.78%, 38.82% respectively, while there was only 1.29% cell viability in the combined PTT and PDT group. These results suggest that the strategy of assembling PPy with MnO₂ for a multifunctional PTT and enhanced PDT nanoplatform was realized, and opens up an unimpeded approach for integrating photothermal reduction materials with MnO₂ for use in synergistic PTT and PDT.

Photothermal-Irradiated Polyethyleneimine-Polypyrrole Nanopigment Film-Coated Polyethylene Fabrics for Infrared-Inspired with Pathogenic Evaluation

Influenza, pneumonia, and pathogenic infection of the respiratory system are boosted in cold environments. Low temperatures also result in vasoconstriction, restraint of blood flow, and decreased oxygen to the heart, and the risk of a heart attack would increase accordingly. The present face mask fabric fails to preserve its air-filtering function as its electrostatic function vanishes once exposed to water. Therefore, its filtering efficacy would be decreased meaningfully, making it nearly impracticable to reuse the disposable face masks. The urgent requirement for photothermal fabrics is also rising. Nanobased polyethyleneimine-polypyrrole nanopigments (NPP NPs) have been developed and have strong near-infrared spectrum absorption and exceptional photothermal convertible performance. Herein, the mask fabric used PE-fiber-constructed membrane (PEFM) was coated by the binding affinity of the cationic polyethyleneimine component of NPP NPs forming NPP NPs-PEFM. To the best of our knowledge, no study has investigated NPP NP-coated mask fabric to perform infrared red (solar or body) photothermal conversion efficacy to provide biocompatible warming, remotely photothermally captured antipathogen, and antivasoconstriction in vivo. This pioneering study showed that the developed NPP NPs-PEFM could be washable, reusable, breathable, biocompatible, and photothermal conversable for active eradication of pathogenic bacteria. Further, it possesses warming preservation and antivasoconstriction.

Recent advances in nanosized metal organic frameworks for drug delivery and tumor therapy

Metal organic-frameworks (MOFs) are novel materials that have attracted increasing attention for applications in a wide range of research, owing to their unique advantages including their small particle size, porous framework structure and high specific surface area. Because of their adjustable size, nanoscale MOFs (nano-MOFs) can be prepared as carriers of biotherapy drugs, thus enabling biotherapeutic applications. Nano-MOFs' metal ion catalytic activity and organic group functional characteristics can be exploited in biological treatments. Furthermore, the applications of nano-MOFs can be broadened by hybridization with other materials to form composites. This review focuses on the preparation and recent advances in nano-MOFs as drug carriers, therapeutic materials and functionalized materials in drug delivery and tumor therapy based on the single/multiple stimulus response of drug release to achieve the targeted therapy, offering a comprehensive reference for drug carrier design. At the end, the current challenges and prospects are discussed to provide significant insight into the design and applications of nano-MOFs in drug delivery and tumor therapy.

A portable device with low-power consumption for monitoring mouse vital signs during in vivo photoacoustic imaging and photothermal therapy

OBJECTIVE

The aim of this study was to monitor the physiological changes and cytotoxic effects of exogenous contrast agents during photoacoustic imaging (PAI) and photothermal therapy (PTT). In this paper, a low-power telemetric device for mouse vital signs monitoring was designed and demonstrated.

APPROACH

The power consumption was optimized through hardware and software co-design with a 17% increased operating time compared with typical operation. To demonstrate the feasibility of the monitoring device, PAI and PTT experiments with chitosan-polypyrrole nanocomposites (CS-PPy NCs) as exogenous contrast agents were conducted. Herein, the physiological variation in groups of mice with different CS-PPy NC concentrations was observed and analyzed.

MAIN RESULTS

The experimental results indicated the influence of CS-PPy NCs and anesthesia on mouse vital signs in PAI and PTT. Additionally, the association between core temperature, heart rate, and saturation of peripheral oxygen (SpO₂) during PAI and PTT was shown. The strong near-infrared absorbance of exogenous contrast agents could account for the increase in mouse core temperature and tumor temperature in this study. Furthermore, high cross-correlation values between core temperature, heart rate, and SpO₂ were demonstrated to explain the fluctuation of mouse vital signs during PAI and PTT.

SIGNIFICANCE

A design of a vital signs monitoring device, with low power consumption, was introduced in this study. A high cross correlation coefficient of mouse vital signs and the effects of CS-PPy NCs were observed, which explained the mouse physiological variation during the PAI and PTT experiments.

Evaluating Donor Effects in Isoindigo-Based Small Molecular Fluorophores

Small molecular organic fluorophores have garnered significant interest because of their indispensable use in fluorescence imaging (FI) and optoelectronic devices. Herein, we designed triphenylamine (TPA)-capped donor-acceptor-donor (D-A-D)-based fluorophores having a variation at the heterocyclic donor (D) units, 3,4-ethylenedioxythiophene (EDOT), furan (FURAN), thiophene (THIO), and 1-methyl-1H-pyrrole (MePyr), with isoindigo as the core electron acceptor (A) unit. Synthesis of these fluorophores (II-X-TPA) resulted in four symmetrical dye molecules: II-EDOT-TPA, II-FURAN-TPA, II-THIO-TPA, and II-MePyr-TPA, where TPA functioned as a terminal unit and a secondary electron donor group. Photophysical, electrochemical, and computational analyses were conducted to investigate the effect of heterocyclic donor units on the II-X-TPA derivatives. Density functional theory (DFT) and time-dependent DFT (TD-DFT) calculations provided insightful features of structural and electronic properties of each fluorophore and correlated well with experimental observations. Electron density distribution maps, overlapping frontier molecular orbital diagrams, and highest occupied molecular orbital (HOMO) to lowest unoccupied molecular orbital (LUMO) electron transfer indicated intramolecular charge transfer (ICT). Theoretical studies confirmed the experimental HOMO energy trend and demonstrated its crucial importance in understanding each heterocycle's donor ability. Stokes shifts of up to ∼178 nm were observed, whereas absorptions and emissions were shifted deeper into the NIR region, resulting from ICT. Results suggest that this isoindigo fluorophore series has potential as a molecular scaffold for the development of efficient FI agents. The studied fluorophores can be further tuned with different donor fragments to enhance the ICT and facilitate in shifting the optical properties further into the NIR region.

A Hybrid Organo-Nanotheranostic Platform of Superlative Biocompatibility for Near-Infrared-Triggered Fluorescence Imaging and Synergistically Enhanced Ablation of Tumors

The quest for an all-organic nanosystem with negligible cytotoxicity and remarkable in vivo tumor theranostic capability is inescapably unending. Hitherto, the landscape of available photothermal agents is dominated by metal-based nanoparticles (NPs) with attendant in vivo negatives. Here, an all-organic-composed theranostic nanosystem with outstanding biocompatibility for fluorescence image-guided tumor photothermal therapy, and as a potential alternative to metal-based photothermal agents is developed. This is rationally achieved by compartmentalizing indocyanine green (ICG) in glycol chitosan (GC)-polypyrrole (PP) nanocarrier to form hybrid ICG@GC-PP NPs (≈65 nm). The compartmentalization strategy, alongside the high photothermal conversion ability of PP jointly enhances the low photostability of free ICG. Advantageously, ICG@GC-PP is endowed with an impeccable in vivo performance by the well-known biocompatibility track records of its individual tri organo-components (GC, PP, and ICG). As a proof of concept, ICG@GC-PP NPs enables a sufficiently prolonged tumor diagnosis by fluorescence imaging up to 20 h post-injection. Furthermore, owing to the complementary heating performances of PP and ICG, ICG@GC-PP NPs-treated mice by one-time near-infrared irradiation exhibit total tumor regression within 14 days post-treatment. Therefore, leveraging the underlying benefits of this study will help to guide the development of new all-organic biocompatible systems in synergism, for safer tumor theranostics.

Polymyxin-based photosensitizer for the potent and selective killing of Gram-negative bacteria

The methylene blue-polymyxin conjugate demonstrated high selectivity, sensitivity and phototoxicity against Gram-negative bacteria, including in early biofilm models.

Photothermal Responsive Porous Membrane for Treatment of Infected Wound

Wound infection is a big issue of modern medicine because of multi-drug resistance bacteria; thus, developing an advanced therapy is curial. Photothermal therapy (PTT) is a newly noninvasive strategy that employs PTT agents to transfer near-infrared (NIR) light energy into heat to kill bacterial pathogens. In this work, the PTT agent-containing dressing was developed for the first time to treat the wound infection. Palladium nanoparticles (PdNPs) were chosen as PTT agents because of their high stability, good biocompatibility, excellent photothermal property, and simple-green preparation. With the flexibility and wettability, highly porous membrane chitosan/polyvinyl alcohol (CS/PVA) membrane was chosen as the dressing. The prepared wound dressings exhibited excellent biocompatibility, high porosity, a high degree of swelling, high moisture retention, and high photothermal performance. The treatment of PdNPs loading CS/PVA dressing (CS/PVA/Pd) and laser irradiation killed most of the bacteria in vitro. The proposed PTT agent containing wound dressing introduces a novel strategy for the treatment of wound infection.

The application of small organic π-conjugated discotic derivatives in photoacoustic imaging and photothermal conversion

Near-infrared absorbing dyes are catching people's attention as they are committed to find materials with greater photoacoustic (PA) and photothermal (PT) effect. In this study, a new series of organic π-conjugated discotic derivatives synthesized via [2 + 2] click chemistry were introduced. The PA intensity and PT conversion effect of the derivatives were monitored. It was found that the π-conjugated discotic derivatives had a proper absorption peak and PA intensity by introducing the click regents. Furthermore, the PA intensity remained relatively high, while B12 molecules were embedded in hydrophobic phospholipid bilayer of liposomes (B12⊂L). The application in biological therapy for tumors become possible as the toxicity of B12⊂L was low. What's more, when B12 molecules embedded in poly (N-isopropylacrylamide)-block-poly (2-nitrobenzyl methacrylate) (PNIPAM-b-PNBM) thermosensitive micelles were irradiated by laser, the molecules could take the place of direct temperature stimulus. This work affords us a way to solve the problem in which direct temperature stimulus is inapplicable.

Molecular Photoacoustic Contrast Agents: Design Principles & Applications

Photoacoustic imaging (PAI) is a rapidly growing field which offers high spatial resolution and high contrast for deep-tissue imaging in vivo. PAI is nonionizing and noninvasive and combines the optical resolution of fluorescence imaging with the spatial resolution of ultrasound imaging. In particular, the development of exogenous PA contrast agents has gained significant momentum of late with a vastly expanding complexity of dye materials under investigation ranging from small molecules to macromolecular proteins, polymeric and inorganic nanoparticles. The goal of this review is to survey the current state of the art in molecular photoacoustic contrast agents (MPACs) for applications in biomedical imaging. The fundamental design principles of MPACs are presented and a review of prior reports spanning from early-to-current literature is put forth.

Photoacoustic Imaging-Guided Photothermal Therapy with Tumor-Targeting HA-FeOOH@PPy Nanorods

Cancer theragnosis agents with both cancer diagnosis and therapy abilities would be the next generation of cancer treatment. Recently, nanomaterials with strong absorption in near-infrared (NIR) region have been explored as promising cancer theragnosis agents for bio-imaging and photothermal therapy (PTT). Herein, we reported the synthesis and application of a novel multifunctional theranostic nanoagent based on hyaluronan (HA)-coated FeOOH@polypyrrole (FeOOH@PPy) nanorods (HA-FeOOH@PPy NRs) for photoacoustic imaging (PAI)-guided PTT. The nanoparticles were intentionally designed with rod-like shape and conjugated with tumor-targeting ligands to enhance the accumulation and achieve the entire tumor distribution of nanoparticles. The prepared HA-FeOOH@PPy NRs showed excellent biocompatible and physiological stabilities in different media. Importantly, HA-FeOOH@PPy NRs exhibited strong NIR absorbance, remarkable photothermal conversion capability, and conversion stability. Furthermore, HA-FeOOH@PPy NRs could act as strong contrast agents to enhance PAI, conducting accurate locating of cancerous tissue, as well as precise guidance for PTT. The in vitro and in vivo photothermal anticancer activity results of the designed nanoparticles evidenced their promising potential in cancer treatment. The tumor-bearing mice completely recovered after 17 days of PTT treatment without obvious side effects. Thus, our work highlights the great potential of using HA-FeOOH@PPy NRs as a theranostic nanoplatform for cancer imaging-guided therapy.

Polypyrrole-coated UCNPs@mSiO2@ZnO nanocomposite for combined photodynamic and photothermal therapy

Under 980 nm light irradiation, polypyrrole-coated UCNPs@mSiO₂@ZnO nanocomposites can convert NIR light to achieve both photodynamic therapy (PDT) and photothermal therapy (PTT).

Synthesis and In Vitro Performance of Polypyrrole-Coated Iron-Platinum Nanoparticles for Photothermal Therapy and Photoacoustic Imaging

Multifunctional nano-platform for the combination of photo-based therapy and photoacoustic imaging (PAI) for cancer treatment has recently attracted much attention to nanotechnology development. In this study, we developed iron-platinum nanoparticles (FePt NPs) with the polypyrrole (PPy) coating as novel agents for combined photothermal therapy (PTT) and PAI. The obtained PPy-coated FePt NPs (FePt@PPy NPs) showed excellent biocompatibility, photothermal stability, and high near-infrared (NIR) absorbance for the combination of PTT and PAI. In vitro investigation experimentally demonstrated the effectiveness of FePt@PPy NPs in killing cancer cells with NIR laser irradiation. Moreover, the phantom test of PAI used in conjunction with FePt@PPy NPs showed a strong photoacoustic signal. Thus, the novel FePt@PPy NPs could be considered as promising multifunctional nanoparticles for further applications of photo-based diagnosis and treatment.