Iron oxide nanoparticles functionalized with novel hydrophobic and hydrophilic porphyrins as potential agents for photodynamic therapy

Comprehensive review on recent trends and perspectives of natural exo-polysaccharides: Pioneering nano-biotechnological tools

Exopolysaccharides (EPSs), originating from various microbes, and mushrooms, excel in their conventional role in bioremediation to showcase diverse applications emphasizing nanobiotechnology including nano-drug carriers, nano-excipients, medication and/or cell encapsulation, gene delivery, tissue engineering, diagnostics, and associated treatments. Acknowledged for contributions to adsorption, nutrition, and biomedicine, EPSs are emerging as appealing alternatives to traditional polymers, for biodegradability and biocompatibility. This article shifts away from the conventional utility to delve deeply into the expansive landscape of EPS applications, particularly highlighting their integration into cutting-edge nanobiotechnological methods. Exploring EPS synthesis, extraction, composition, and properties, the discussion emphasizes their structural diversity with molecular weight and heteropolymer compositions. Their role as raw materials for value-added products takes center stage, with critical insights into recent applications in nanobiotechnology. The multifaceted potential, biological relevance, and commercial applicability of EPSs in contemporary research and industry align with the nanotechnological advancements coupled with biotechnological nano-cleansing agents are highlighted. EPS-based nanostructures for biological applications have a bright future ahead of them. Providing crucial information for present and future practices, this review sheds light on how eco-friendly EPSs derived from microbial biomass of terrestrial and aquatic environments can be used to better understand contemporary nanobiotechnology for the benefit of society.

Enhanced Photodynamic Therapy: A Review of Combined Energy Sources

Photodynamic therapy (PDT) has been used in recent years as a non-invasive treatment for cancer, due to the side effects of traditional treatments such as surgery, radiotherapy, and chemotherapy. This therapeutic technique requires a photosensitizer, light energy, and oxygen to produce reactive oxygen species (ROS) which mediate cellular toxicity. PDT is a useful non-invasive therapy for cancer treatment, but it has some limitations that need to be overcome, such as low-light-penetration depths, non-targeting photosensitizers, and tumor hypoxia. This review focuses on the latest innovative strategies based on the synergistic use of other energy sources, such as non-visible radiation of the electromagnetic spectrum (microwaves, infrared, and X-rays), ultrasound, and electric/magnetic fields, to overcome PDT limitations and enhance the therapeutic effect of PDT. The main principles, mechanisms, and crucial elements of PDT are also addressed.

Nanoformulation of Tetrapyrroles Derivatives in Photodynamic Therapy: A Focus on Bacteriochlorin

Photodynamic therapy (PDT) is a well-known remedial treatment for cancer, infections, and various other diseases. PDT uses nontoxic dyes called photosensitizers (PS) that are activated in visible light at the proper wavelength to generate ROS (reactive oxygen species) that aid in killing tumor cells and destroying pathogenic microbes. Deciding a suitable photosensitizer is essential for enhancing the effectiveness of photodynamic therapy. It is challenging to choose the photosensitizer that is appropriate for specific pathological circumstances, such as different cancer species. Porphyrin, chlorin, and bacteriochlorin are tetrapyrroles used with proper functionalization in PDT, among which some compound has been clinically approved. Most photosensitizers are hydrophobic, have minimum solubility, and exhibit cytotoxicity due to the dispersion in biological fluid. This paper reviewed some nanotechnology-based strategies to overcome these drawbacks. In PDT, metal nanoparticles are widely used due to their enhanced surface plasmon resonance. The self-assembled nano-drug carriers like polymeric micelles, liposomes, and metal-based nanoparticles play a significant role in solubilizing the photosensitizer to make them biocompatible.

Recent Advances in Near Infrared Upconverting Nanomaterials for Targeted Photodynamic Therapy of Cancer

Photodynamic therapy (PDT) is a well-established treatment of cancer that uses the toxic reactive oxygen species, including singlet oxygen (1O2), generated by photosensitiser drugs following irradiation of a specific wavelength to destroy the cancerous cells and tumours. Visible light is commonly used as the excitation source in PDT, which is not ideal for cancer treatment due to its reduced tissue penetration, and thus inefficiency to treat deep-lying tumours. Additionally, these wavelengths exhibit elevated autofluorescence background from the biological tissues which hinders optical biomedical imaging. An alternative to UV-Vis irradiation is the use of near infrared (NIR) excitation for PDT. This can be achieved using upconverting nanoparticles (UCNPs) functionalised with photosensitiser (PS) drugs where UCNPs can be used as an indirect excitation source for the activation of PS drugs yielding to the production of singlet 1O2 following NIR excitation. The use of nanoparticles for PDT is also beneficial due to their tumour targeting capability, either passively via the enhanced permeability and retention (EPR) effect or actively via stimuli-responsive targeting and ligand-mediated targeting (ie. using recognition units that can bind specific receptors only present or overexpressed on tumour cells). Here, we review recent advances in NIR upconverting nanomaterials for PDT of cancer with a clear distinction between those reported nanoparticles that could potentially target the tumour due to accumulation via the EPR effect (passive targeting) and nanoparticle-based systems that contain targeting agents with the aim of actively target the tumour via a molecular recognition process.

Photo-induced processes of iron oxide nanoparticles to enhance laser therapy

Nanoparticles are used as drug carriers to increase the selectivity and effectiveness of therapy, as well as for combined therapy that utilizes different effects. Iron oxide nanoparticles are promising in this aspect. Due to magnetic properties, they can be used as a contrast agent for magnetic resonance imaging. Also, iron oxide nanoparticles could be coated with a photosensitizer for photodynamic therapy and their laser or magnetic heating can be used for phototherapy. Local enhancement of the electromagnetic field near iron oxide nanoparticles can increase the fluorescence intensity of photosensitizers and the efficiency of singlet oxygen generation. This paper presents the results of a study of iron oxide nanoparticles focused on the photophysical aspects of the formation of “hot spots” under laser irradiation. The photoinduced effects of iron oxide nanoparticles observed in in vitro experiments lead to the rupture of lysosomes. Theoretical modeling showed that the heating of iron oxide nanoparticles with a radius of 35 nm under the action of laser radiation is about 89°C and 19°C for wavelengths of 458 and 561 nm, respectively. Local field enhancement occurs in pairs of nanoparticles of various sizes and strongly depends on the distance between them. The maximum gain is achieved at small distances between nanoparticles. For a dimer of nanoparticles with radii of 10 and 35 nm at a distance of 1 nm, an enhancement factor of two orders of magnitude was obtained. The investigated phenomenon of «hot spots» is in demand for precision therapy, because the photo-induced processes occur at small distances between nanoparticles, in areas of their high accumulation.

A possible theranostic approach of chitosan-coated iron oxide nanoparticles against human colorectal carcinoma (HCT-116) cell line

Iron oxides have become increasingly popular for their use as a diagnostic and therapeutic tool in oncology. This study aimed to improve pharmacological valuable of Fe₃O₄, which may be use to diagnosis colorectal cancers (CRC). Here, we have developed chitosan (CS) coated Fe₃O₄ through a cost-effective procedure. First, we determined the characterization of OA-C-Fe₃O₄ by FTIR, UV–Vis spectra, and TEM. Then, we evaluated the photodynamic therapeutic (PDT) activity of OA-C-Fe₃O₄ in human colorectal carcinoma cell lines (HCT 116). Current results revealed that the light-induced enhanced reactive oxygen species (ROS) activity of the nanoparticles (NPs) and caused cell death via the activity of caspase 9/3. The in vitro magnetic resonance imaging (MRI) experiments in (HCT 116) and human embryonic kidney cells (HEK 293) illustrated that nanohybrid is an effective MRI contrasting agents for the diagnosis of colorectal cancer.

Metallocatanionic vesicles mediated enhanced singlet oxygen generation and photodynamic therapy of cancer cells

In clinics, photodynamic therapy (PDT) is established as a non-invasive therapeutic modality for certain types of cancers and skin diseases. However, due to poor water solubility, photobleaching, and dark toxicity...

Low Blue Dose Photodynamic Therapy with Porphyrin-Iron Oxide Nanoparticles Complexes: In Vitro Study on Human Melanoma Cells

The purpose of this study was to investigate the effectiveness in photodynamic therapy of iron oxide nanoparticles (γ-Fe2O3 NPs), synthesized by laser pyrolysis technique, functionalized with 5,10,15,20-(Tetra-4-sulfonatophenyl) porphyrin tetraammonium (TPPS) on human cutaneous melanoma cells, after only 1 min blue light exposure. The efficiency of porphyrin loading on the iron oxide nanocarriers was estimated by using absorption and FTIR spectroscopy. The singlet oxygen yield was determined via transient characteristics of singlet oxygen phosphorescence at 1270 nm both for porphyrin functionalized nanoparticles and rose bengal used as standard. The irradiation was performed with a LED (405 nm, 1 mW/cm2) for 1 min after melanoma cells were treated with TPPS functionalized iron oxide nanoparticles (γ-Fe2O3 NPs_TPPS) and incubated for 24 h. Biological tests revealed a high anticancer effect of γ-Fe2O3 NPs_TPPS complexes indi-cated by the inhibition of tumor cell proliferation, reduction of cell adhesion, and induction of cell death through ROS generated by TPPS under light exposure. The biological assays were combined with the pharmacokinetic prediction of the porphyrin.

An Anti-inflammatory Fe3 O4 -Porphyrin Nanohybrid Capable of Apoptosis through Upregulation of p21 Kinase Inhibitor Having Immunoprotective Properties under Anticancer PDT Conditions

We report the influence of Fe₃ O₄ nanoparticles (NPs) on porphyrins in the development of photosensitizers (PSs) for efficient photodynamic therapy (PDT) and possible post-PDT responses for inflicting cancer cell death. Except for Au, most metal-based nanomaterials are unsuitable for clinical applications. The US Food and Drug Administration and other agencies have approved Feraheme and a few other iron oxide NPs for clinical use, paving the way for novel biocompatible immunoprotective superparamagnetic iron oxide nanohybrids to be developed as nanotherapeutics. A water-soluble nanohybrid, referred to here as E-NP, comprising superparamagnetic Fe₃ O₄ NPs functionalised with tripyridyl porphyrin PS was introduced through a rigid 4-carboxyphenyl linker. As a PDT agent, the efficacy of E-NP toward the AGS cancer cell line showed enhanced photosensitising ability as determined through in vitro photobiological assays. The cellular uptake of E-NPs by AGS cells led to apoptosis by upregulating ROS through cell-cycle arrest and loss of mitochondrial membrane potential. The subcellular localisation of the PSs in mitochondria stimulated apoptosis through upregulation of p21, a proliferation inhibitor capable of preventing tumour development. Under both PDT and non-PDT conditions, this nanohybrid can act as an anti-inflammatory agent by decreasing the production of NO and superoxide ions in murine macrophages, thus minimising collateral damage to healthy cells.

Overcoming barriers in photodynamic therapy harnessing nano-formulation strategies

Photodynamic therapy (PDT) has been extensively investigated for decades for tumor treatment because of its non-invasiveness, spatiotemporal selectivity, lower side-effects, and immune activation ability. It can be a promising treatment modality in several medical fields, including oncology, immunology, urology, dermatology, ophthalmology, cardiology, pneumology, and dentistry. Nevertheless, the clinical application of PDT is largely restricted by the drawbacks of traditional photosensitizers, limited tissue penetrability of light, inefficient induction of tumor cell death, tumor resistance to the therapy, and the severe pain induced by the therapy. Recently, various photosensitizer formulations and therapy strategies have been developed to overcome these barriers. Significantly, the introduction of nanomaterials in PDT, as carriers or photosensitizers, may overcome the drawbacks of traditional photosensitizers. Based on this, nanocomposites excited by various light sources are applied in the PDT of deep-seated tumors. Modulation of cell death pathways with co-delivered reagents promotes PDT induced tumor cell death. Relief of tumor resistance to PDT with combined therapy strategies further promotes tumor inhibition. Also, the optimization of photosensitizer formulations and therapy procedures reduces pain in PDT. Here, a systematic summary of recent advances in the fabrication of photosensitizers and the design of therapy strategies to overcome barriers in PDT is presented. Several aspects important for the clinical application of PDT in cancer treatment are also discussed.

Photodynamic Antimicrobial Chemotherapy: Advancements in Porphyrin-Based Photosensitize Development

The reduction of available drugs with effectiveness against microbes is worsening with the current global crisis of antimicrobial resistance. This calls for innovative strategies for combating antimicrobial resistance. Photodynamic Antimicrobial Chemotherapy (PACT) is a relatively new method that utilizes the combined action of light, oxygen, and a photosensitizer to bring about the destruction of microorganisms. This technique has been found to be effective against a wide spectrum of microorganisms, including bacteria, viruses, and fungi. Of greater interest is their ability to destroy resistant strains of microorganisms and in effect help in combating the emergence of antimicrobial resistance. This manuscript reviews porphyrins and porphyrin-type photosensitizers that have been studied in the recent past with a focus on their structure-activity relationship.

Synthesis of axially disubstituted silicon phthalocyanines and investigation of their in vitro cytotoxic/phototoxic anticancer activities

In this study, two SiPcs have been selected and the photodynamic therapy potentials were evaluated of the Pcs. Synthesis of Axially 2-decyn-1-oxy disubstituted Es-SiPc-2 was newly synthesized by the reaction of SiPcCl2 with 2-decyn-1-ol in the presence of NaH in toluene. Furthermore, their nuclear imaging potentials were evaluated in human colon adenocarcinoma (HT-29) and human lung fibroblast cell (WI-38) cell lines. The uptake results have indicated that Es-SiPc labeled with [Formula: see text]I radionuclide ([Formula: see text]I-Es-SiPc) was approximately 2-fold higher in the HT-29 cell line than the WI-38 cell line. In other words, the target/non-target tissue ratio is defined as two in the HT-29/WI-38 cell lines. Besides, the uptake values of [Formula: see text]I-Es-SiPc were found to be higher than [Formula: see text]I-Es-SiPc-2. [Formula: see text]I-Es-SiPc and [Formula: see text]I-Es-SiPc-2 are promising for imaging or treating colon adenocarcinoma. In vitrophotodynamic therapy (PDT) studies have shown that both compounds are suitable and can be used in this field. Also, Es-SiPc has been shown to have higher phototoxicity than Es-SiPc-2.

Chemical approaches for the enhancement of porphyrin skeleton-based photodynamic therapy

With the development of photodynamic therapy (PDT), remarkable studies have been conducted to generate photosensitisers (PSs), especially porphyrin PSs. A variety of chemical modifications of the porphyrin skeleton have been introduced to improve cellular delivery, stability, and selectivity for cancerous tissues. This review aims to highlight the developments in porphyrin-based structural modifications, with a specific emphasis on the role of PDT in anticancer treatment and the design of PSs to achieve a synergistic effect on multiple targets.

Magnetic Nanoplatforms for in Situ Modification of Macromolecules: Synthesis, Characterization, and Photoinactivating Power of Cationic Nanoiman-Porphyrin Conjugates

A nanoplatform concept was developed to synthesize accessible photoactive magnetic nanoparticles (MNPs) of Fe₃O₄ coated with silica. This approach was based on the covalent binding of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (TPPF₂₀) to aminopropyl-grafted MNPs by nucleophilic aromatic substitution reaction (S_NAr) to obtain conjugate MNP-P1. After in situ modification, the remaining pentafluorophenyl groups of TPPF₂₀ attached to MNPs were substituted by dimethylaminoethoxy groups to form MNP-P2. The basic amine group of these conjugates can be protonated in aqueous media. In addition, MNP-P1 and MNP-P2 were intrinsically charged to produce cationic conjugates MNP⁺-P1 and MNP⁺-P2⁺ by methylation. All of them were easily purified by magnetic decantation in high yields. The average size of the MNPs was ∼15 nm, and the main difference between these conjugates was the greater coating with positive charges of MNP⁺-P2⁺, as shown by the zeta potential values. Absorption spectra exhibited the Soret and Q bands characteristic of TPPF₂₀ linked to MNPs. Furthermore, these conjugates showed red fluorescence emission of porphyrin with quantum yields of 0.011-0.036. The photodynamic effect sensitized by the conjugates indicated the efficient formation of singlet molecular oxygen in different media, reaching quantum yield values of 0.17-0.34 in N,N-dimethylformamide. The photodynamic activity of the conjugates was evaluated to inactivate the Gram-positive bacteria Staphylococcus aureus, the Gram-negative bacteria Escherichia coli, and the yeast Candida albicans. The modified cationic MNP⁺-P2⁺ was the most effective conjugate for photodynamic inactivation (PDI) of microorganisms. Binding of this conjugate to bacteria and photoinactivation capability was checked by means of fluorescence microscopy. Also, sustainable use by recycling was determined after three PDI treatments. Therefore, this methodology is a suitable scaffold for the in situ modification of conjugates, and in particular, MNP⁺-P2⁺ represents a useful photodynamic active material to eradicate microorganisms.

Trastuzumab conjugated porphyrin-superparamagnetic iron oxide nanoparticle: A potential PTT-MRI bimodal agent for herceptin positive breast cancer

BACKGROUND

Theranostic agents can combine photosensitizers and contrast agents into a single unit for photothermal therapy (PTT) and magnetic resonance imaging (MRI). The possibility of treating and diagnosing malignant cancers without any ionizing radiation could become an option. This study investigates the theranostic potential of Fe₃O₄ nanoparticles (IONs) for the diagnosis and treatment of cancer by developing a single integrated nanoprobe.

METHODS

Oleylamin-coated IONs (ION-Ol) were synthesized and surface of the IONs was modified using protoporphyrin (PP) and trastuzumab (TZ) to develop the TZ-conjugated SPION-porphyrin [ION-PP-TZ]. The structure, morphology, size, and cytotoxicity of all samples were investigated using Fourier-transform infrared spectroscopy (FT-IR), Transmission electron microscopy (TEM), X-ray powder diffraction (XRD), WST-1 assay, respectively. In addition to MRI and in vitro laser irradiation (808 nm, 200 mW) to determine the r₂ values and photothermal ablation.

RESULTS

The sizes of monodispersed nanoparticles were measured in rang 5.74-7.17 nm. No cytotoxicity was observed after incubating MCF 7 cells under various Fe concentrations of nanoparticles and theranostic agents. The transverse relaxation time of the protoporphyrin conjugated to IONs (52.32 mM^-1s^-1) exceeded that of ION-Ol and TZ-conjugated ION-PP. In addition, the in vitro photothermal ablation of ION-PP-TZ revealed a 74 % MCF 7 cell reduction after 10 min of at the highest Fe concentration (1.00 mg Fe/mL).

CONCLUSIONS

In summary, the water-soluble ION-PP-TZ is a promising bimodal agent for the diagnosis and treatment of human epidermal growth factor receptor 2-positive breast cancer cells using a T₂ MRI contrast agent and photothermal therapy.

Novel Polymeric Micelles-Coated Magnetic Nanoparticles for In Vivo Bioimaging of Liver: Toxicological Profile and Contrast Enhancement

Magnetic nanoparticles are intensively studied for magnetic resonance imaging (MRI) as contrast agents but yet there remained some gaps regarding their toxicity potential and clinical implications of their biodistribution in organs. This study presents the effects induced by magnetite nanoparticles encapsulated in polymeric micelles (MNP-DSPE-PEG) on biochemical markers, metabolic functions, and MRI signal in CD1 mice liver. Three groups of animals, one control and the other ones injected with a suspension of five, respectively, 15 mg Fe/kg bw nanoparticles, were monitored up to 14 days. The results indicated the presence of MNP-DSPE-PEG in the liver in the first two days of the experiment. The most significant biochemical changes also occurred in the first 3 days after exposure when the most severe histological changes were observed. The change of the MRI signal intensity on the T2-weighted images and increased transverse relaxation rates R2 in the liver were observed after the first minutes from the nanoparticle administration. The study shows that the alterations of biomarkers level resulting from exposure to MNP-DSPE-PEG are restored in time in mice liver. This was associated with a significant contrast on T2-weighted images and made us conclude that these nanoparticles might be potential candidates for use as a contrast agent in liver medical imaging.

Visible light promoted porphyrin-based metal-organic adduct

Supramolecular adducts formed by a commercial porphyrin derivative and silver nanoparticles have been obtained using exclusively light as an external trigger that is able to promote the formation of the plasmonic nanostructures. In particular, a water-soluble porphyrin, i.e. tetrakis(4-carboxyphenyl)porphyrin, has been used. It has been thoroughly characterized by means of UV-vis and fluorescence spectroscopy in order to explain its peculiar behavior when illumined with visible photons. Herein we demonstrate that, by means of light illumination, it is possible to tune the porphyrin aggregation state. Furthermore, when the monomeric form of the organic macrocycle is induced and a controlled amount of AgNO[Formula: see text] is simultaneously dissolved, it is possible to promote the formation of silver nanostructures using visible light. The proposed approach allowed porphyrin derivatives/Ag nanoparticles hybrid nanostructures to be obtained without using a chemical reducing agent: the porphyrin derivative simultaneously acts as reducing agent when irradiated by visible light and as a capping agent for the silver nanostructures. The organic/inorganic adduct was characterized by means of steady-state fluorescence that highlights a strong energetic or electronic communication between the two species. XRD and SEM investigations evidence that silver nanoparticles are formed without using any reducing agent.

Recent advances in porphyrin-based nanocomposites for effective targeted imaging and therapy

Porphyrins are organic compounds that continue to attract much theoretical interest, and have been called the "pigments of life". They have a wide role in photodynamic and sonodynamic therapy, along with uses in magnetic resonance, fluorescence and photoacoustic imaging. There is a vast range of porphyrins that have been isolated or designed, but few of them have real clinical applications. Due to the hydrophobic properties of porphyrins, and their tendency to aggregate by stacking of the planar molecules they are difficult to work with in aqueous media. Therefore encapsulating them in nanoparticles (NPs) or attachment to various delivery vehicles have been used to improve delivery characteristics. Porphyrins can be used in a composite designed material with properties that allow specific targeting, immune tolerance, extended tissue lifetime and improved hydrophilicity. Drug delivery, healing and repairing of damaged organs, and cancer theranostics are some of the medical uses of porphyrin-based nanocomposites covered in this review.

Enhancement of Photodynamic Cancer Therapy by Physical and Chemical Factors

The viable use of photodynamic therapy (PDT) in cancer therapy has never been fully realized because of its undesirable effects on healthy tissues. Herein we summarize some physicochemical factors that can make PDT a more viable and effective option to provide future oncological patients with better-quality treatment options. These physicochemical factors include light sources, photosensitizer (PS) carriers, microwaves, electric fields, magnetic fields, and ultrasound. This Review is meant to provide current information pertaining to PDT use, including a discussion of in vitro and in vivo studies. Emphasis is placed on the physicochemical factors and their potential benefits in overcoming the difficulty in transitioning PDT into the medical field. Many advanced techniques, such as employing X-rays as a light source, using nanoparticle-loaded stem cells and bacteriophage bio-nanowires as a photosensitizer carrier, as well as integration with immunotherapy, are among the future directions.

Singlet oxygen generation from porphyrin-functionalized hexahedral polysilicon microparticles

The generation of singlet oxygen (SO), primarily by using a combination of light and photosensitizers in the presence of a dissolved gas, finds applications in both chemistry and medicine. The efficiency of its formation can be enhanced by immobilization of the photosensitizers. In this work, we have explored the covalent functionalization in suspension of hexahedral slab-like polysilicon microparticles ( [Formula: see text]P, with a largest dimension of three microns) with a model photosensitizer, 5-(4-isothiocyanatophenyl)-10,15,20-(triphenyl)porphyrin (ITC-P), and evaluated the singlet oxygen generation of this photosensitizer in solution and after immobilization (ITC-P-[Formula: see text]P) in suspension. The SO-detection experiment on the functionalized microparticles was performed using a hydrogel as the matrix supporting the microparticles (to avoid their settling), and revealed that ITC-P-[Formula: see text]Pin suspension is capable of generating SO more efficiently than free ITC-P in solution.

Optimizing the removal of nitrate from aqueous solutions via reduced graphite oxide-supported nZVI: synthesis, characterization, kinetics, and reduction mechanism

Graphene has been considered an ideal absorbent and excellent carrier for nanoparticles. Reduced graphite oxide (rGO)-supported nanoscale zero-valent iron (nZVI@rGO) is an effective material for removing nitrate from water. nZVI@rGO nanocomposites were prepared by a liquid-phase reduction method and then applied for nitrate-nitrogen (NO₃^--N) removal in aqueous solution under anaerobic conditions. The experimental results showed that the stability and activity of the nZVI@rGO nanocomposites were enhanced compared with those of nZVI. The influence of the reaction conditions, including the initial concentration of NO₃^--N, coexisting anions, initial pH of the solution, and water temperature, on NO₃^--N removal was also investigated by batch experiments. In a neutral or slightly alkaline environment, 90% of NO₃^--N at a concentration less than 50 mg/L could be removed within 1 h, and nitrogen production was approximately 15%. The process of NO₃^--N removal by nZVI@rGO fits well with different reaction kinetics. In addition, magnetite was the main oxidation product. RGO-supported nZVI might become a promising filler in the permeable reactive barrier process for groundwater remediation.

Revisiting Current Photoactive Materials for Antimicrobial Photodynamic Therapy

Microbial infection is a severe concern, requiring the use of significant amounts of antimicrobials/biocides, not only in the hospital setting, but also in other environments. The increasing use of antimicrobial drugs and the rapid adaptability of microorganisms to these agents, have contributed to a sharp increase of antimicrobial resistance. It is obvious that the development of new strategies to combat planktonic and biofilm-embedded microorganisms is required. Photodynamic inactivation (PDI) is being recognized as an effective method to inactivate a broad spectrum of microorganisms, including those resistant to conventional antimicrobials. In the last few years, the development and biological assessment of new photosensitizers for PDI were accompanied by their immobilization in different supports having in mind the extension of the photodynamic principle to new applications, such as the disinfection of blood, water, and surfaces. In this review, we intended to cover a significant amount of recent work considering a diversity of photosensitizers and supports to achieve an effective photoinactivation. Special attention is devoted to the chemistry behind the preparation of the photomaterials by recurring to extensive examples, illustrating the design strategies. Additionally, we highlighted the biological challenges of each formulation expecting that the compiled information could motivate the development of other effective photoactive materials.

Chirality Enhancement of Porphyrin Supramolecular Assembly Driven by a Template Preorganization Effect

Cationic polylysine promotes, under neutral conditions, the spontaneous aggregation of opposite charged ZnTPPS in water. Spectroscopic investigations evidence a different preorganization of ZnTPPS onto the polypeptide matrix depending on the chain length. Spinodal decomposition theory in confined geometry is used to model this mechanism by considering the time evolution of a homogeneous distribution of randomly adsorbed particles (porphyrins) onto a rodlike polyelectrolyte (polymer) of variable length L.

Synthesis of carbon dots from Hypocrella bambusae for bimodel fluorescence/photoacoustic imaging-guided synergistic photodynamic/photothermal therapy of cancer

As phototheranostic agents, carbon dots (CDs), have recently drawn considerable attention due to their excellent physicochemical properties. However, the complex synthetic route and high-cost of CDs greatly limit their practical application. To address this issue, given their nearly infinite supply from nature, Hypocrella bambusae is used as the precursor for the preparation of CDs in this study. The obtained Hypocrella bambusae CDs (HBCDs) possess good water solubility, broad absorption (350-800 nm), red-light emission (maximum peak at 610 nm), and low biotoxicity. Moreover, HBCDs can highly generate ¹O₂ (0.38) and heat (27.6%) under 635 nm laser irradiation. These excellent properties of HBCDs capacitate them to be utilized for bimodal fluorescence/photoacoustic imaging-guided synergistic photodynamic therapy (PDT)/photothermal therapy (PTT). This work provides a new candidate for tumor treatment with the combination of PDT and PTT, and explores a novel approach for the preparation of CD-based phototheranostic agents with natural biomass as raw carbon sources.

Chemistry and engineering of cyclodextrins for molecular imaging

Cyclodextrins (CDs) are naturally occurring cyclic oligosaccharides bearing a basket-shaped topology with an "inner-outer" amphiphilic character. The abundance of hydroxyl groups enables CDs to be functionalized with multiple targeting ligands and imaging elements. The imaging time, and the payload of different imaging elements, can be tuned by taking advantage of the commercial availability of CDs with different sizes of the cavity. This review aims to offer an outlook of the chemistry and engineering of CDs for the development of molecular probes. Complexation thermodynamics of CDs, and the corresponding implications for probe design, are also presented with examples demonstrating the structural and physiochemical roles played by CDs in the full ambit of molecular imaging. We hope that this review not only offers a synopsis of the current development of CD-based molecular probes, but can also facilitate translation of the incremental advancements from the laboratory to real biomedical applications by illuminating opportunities and challenges for future research.

Construction of iron oxide nanoparticle-based hybrid platforms for tumor imaging and therapy

This review highlights the most recent progress in the construction of iron oxide nanoparticle-based hybrid platforms for tumor imaging and therapy.

Biological evaluation of a Porphyrin-SPION nanoconjugate as an antimicrobial magnetic photosensitizer

The present work describes the use of a magnetic porphyin (5-(4-carboxy-phenyl)-10,15,20-triphenyl-21H, 23H-porphyrin TPP) nanoconjugate (SPION-TPP) for destroying pathogenic bacteria followed by the recovery of the magnetic photosensitizer. SPION-TPP was tested for its activity against two different gram-positive bacterial strains (Staphylococcus aureus and Steptoccoccus mutans). It is observed that SPION-TPP at a very low concentration of 0.5 [Formula: see text]M is effective in destroying gram-positive bacteria (10[Formula: see text]–10[Formula: see text] CFU ml[Formula: see text] S. aureus with several orders reduction and few orders in S. mutans. The aim of this work is to combine photoactivity against microorganisms imparted by the photosensitizer with the possibility of recovering the nanoconstruct with magnets for disposal/reuse.

Zero-valent iron-facilitated reduction of nitrate: Chemical kinetics and reaction pathways

The kinetics and mechanisms of the reduction of NO₃^- in solution to NH₃ by 1.5μm diameter zero-valent iron (ZVI_1.5) particles has been examined. The effects of initial pH, ZVI_1.5 particle concentration and initial NO₃^- concentration were also investigated. Results indicate that denitrification by ZVI_1.5 is primarily a pH-dependent, surface-mediated process. At an initial ZVI_1.5 concentrations of 0.832g/L, and an optimal initial pH of 1.62, the NO₃^- concentration was reduced by 95% from 12.50mg/L-N to 0.65mg/L-N, in 120min. Several kinetic models were used to describe the denitrification process based on the ZVI_1.5:NO₃^- ratio. Based on mineralogical and surface analysis of the reacted ZVI_1.5, and detailed solution chemical analysis, the denitrification reaction pathway involves oxidation and partial dissolution of the ZVI_1.5 with the generation of Fe²⁺ and NO₂^- intermediates prior to formation of Fe³⁺ oxyhydroxide (goethite) and NH₃.