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The treatment and prognosis of cancers of the nervous system remain unfavorable to the patient, which makes it necessary to study alternative therapies as primary or adjuvant treatments to existing methods. Photodynamic Therapy (PDT) is a method that consists of combining a photosensitizer (PS), a light source at the appropriate wavelength, and molecular oxygen, forming reactive oxygen species (ROS), leading to death in the target cell. The objective of this work was to compare the effects of PDT with two chlorins, Photodithazine (PDZ) and Fotoenticine (FTC), in 9L/lacZ gliosarcoma cell lines. Both chlorins, together with an LED device at 660 nm with a fluence of 10 J/cm², were included in the study. It was observed that the response to therapy depends on the concentration and type of PS used. In addition, PDZ showed a higher quantum yield of singlet oxygen generation than FTC.

Templated-MgO nanoribbons are able to curl up into nanometric spheres under ultrasound irradiation.

Ncediwe Tsolekile,1– 3 Sundararajan Parani,2,3 Erenilda Ferreira de Macedo,4 Thabang Calvin Lebepe,2,3 Rodney Maluleke,2,3 Vuyelwa Ncapayi,2,3 Mangaka Clara Matoetoe,1 Sandile Phinda Songca,5 Katia Conceição,6 Dayane Batista Tada,4 Oluwatobi Samuel Oluwafemi2,3 1Department of Chemistry, Cape Peninsula University of Technology, Cape Town, 2000, South Africa; 2Department of Chemical Sciences, University of Johannesburg, Johannesburg, 2028, South Africa; 3Centre for Nanomaterials Science Research, University of Johannesburg, Johannesburg, South Africa; 4Laboratory of Nanomaterials and Nanotoxicology, Institute of Science and Technology, Federal University of São Paulo, São Paulo, Brazil; 5Department of Chemistry, University of KwaZulu-Natal, Durban, 4000, South Africa; 6Laboratory of Peptide Biochemistry, Institute of Science and Technology, Federal University of São Paulo, São Paulo, BrazilCorrespondence: Oluwatobi Samuel Oluwafemi, Department of Chemical Sciences, University of Johannesburg, P. O. Box 17011, Doornfontein, Johannesburg, 2028, South Africa, Tel +27 011 559 9060, Email oluwafemi.oluwatobi@gmail.com Dayane Batista Tada, Laboratório de Nanomateriais e Nanotoxicologia, Universidade Federal de São Paulo, Talim, 330 - Vila Nair, São José dos Campos, São Paulo, 12231-280, Brazil, Email day.tada@gmail.comBackground: Photodynamic therapy (PDT) is a non-invasive treatment modality that destroys abnormally growing cells or microorganisms. Porphyrins are used as photosensitizers in PDT; however, their clinical application has been limited by their poor water solubility, resulting in aggregation and low quantum yields of reactive oxygen species (ROS).Methods: To overcome these limitations and improve PDT efficacy, we herein report the conjugation of ZnCuInS/ZnS (ZCIS/ZnS) quantum dots (QDs) to 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin (mTHPP). The optimal conditions for QDs porphyrin conjugation formation were systematically evaluated.Discussion: This study further assessed the PDT efficacy and antibacterial potency of the synthesized ZCIS/ZnS-mTHPP conjugates. The PDT efficacy of the QDs, mTHPP, and conjugate was evaluated against the murine metastatic melanoma (B16 F10 Nex2) cell line. This was performed with and without LED irradiation.Results: The conjugate exhibited the highest reduction in cell viability following LED irradiation (72%) compared to the bare QDs (19%) and mTHPP (1%). Antimicrobial studies conducted on E. coli showed that the conjugation exhibits a higher antibacterial effect than the bare QDs, even without light.Conclusion: The results suggest that conjugate is a promising class of materials for anti-cancer and antimicrobial PDT.Keywords: Zn-Cu-In-S/ZnS QDs, 5,10,15,20-tetrakis(hydroxyphenyl)porphyrin, mTHPP, photodynamic therapy, murine metastatic melanoma (B16F10-Nex2), antibacterial activity

Sensors based on the surface plasmon resonance (SPR) technique are useful devices to detect and monitor interactions between biomolecules in real-time. SPR is a label-free method that monitors the variation of reflectivity of a biochip composed of a metal-coated glass prism and can be applied in several areas, such as biotechnology, food safety and clinical diagnosis. In the last years, several researchers have proven the efficiency of metallic nanoparticles (NPs) in the enhancement of SPR signal. This feature allowed the detection of biomolecules at very low concentration. Aiming to further enhance SPR signal towards the detection of proteins at low concentration and by a simple procedure, the present work compared the performance of gold and platinum bimetallic NPs (AuPtNPs) with that of monometallic gold NPs (AuNPs) in the enhancement of SPR signal. In order to evaluate the NPs, protein peanut agglutin (PNA) was used as target analyte and anti-PNA antibody was used as sensing molecule. Firstly NPs were functionalized with anti-PNA antibody and incubated with a solution containing PNA. Then, the NPs bound to PNA were injected into the SPR equipment containing a biochip previously modified with anti-PNA antibody. The results demonstrated that the AuPtNPs provided a 91-fold increase compared to the direct detection of free PNA in solution. In comparison with AuNPs, the signal generated by AuPtNPs was about 4 times higher. This encouraging result indicated that the application of bimetallic NPs may be a better strategy to further enhance sensitivity of SPR biosensors and could drive the development of new strategies that are not only simple, but also able to detect proteins at low concentrations, which is of great importance, especially in clinical diagnostics.

Nanoparticles (NPs) are a promising strategy for delivering drugs to specific sites because of their tunable size and surface chemistry variety. Among the availablematerials, NPs prepared with biopolymers are of particular interest because of their biocompatibility and controlled release of encapsulated drugs. Poly lactic-co-glycolic acid (PLGA) is one of the most widely used biopolymers in biomedical applications. In addition to material choice modulation of the interaction between NPs and biological systems is essential for the safety and effective use of NPs. Therefore, this work focused on evaluating different surface functionalization strategies to promote cancer cell uptake and intracellular targeting of PLGA NPs. Herein, cell-penetrating peptides (CPPs) were shown to successfully drive PLGA NPs to the mitochondria and nuclei. Furthermore, the functionalization of PLGA NPs with peptide AC-1001 H3 (GQYGNLWFAY) was proven to be useful for targeting actin filaments. The PLGA NPs cell internalization mechanism by B16F10-Nex2 cells was identified as caveolae-mediated endocytosis, which could be inhibited by the presence of methyl-β-cyclodextrin. Notably, when peptide C (CVNHPAFAC) was used to functionalize PLGA NPs, none of the tested inhibitors could avoid cell internalization of PLGA NPs. Therefore, we suggest this peptide as a promising surface modification agent for enhancing drug delivery to cancer cells. Finally, PLGA NPs showed slow release kinetics and low cytotoxic profile, which, combined with the surface functionalization strategies addressed in this study, highlight the potential of PLGA NPs as a drug delivery platform for improving cancer therapy.

The development of resistance against photodamage triggered by photodynamic therapy (PDT) is ascribed mainly to the cellular redox defenses and repair. If the tumor tissue is not promptly eliminated by the first few PDT sessions, PDT-resistance can be favored, challenging the efficacy of the treatment. Although the mechanism of PDT resistance is still unclear, in vitro assays have evidenced that it can be developed through the PARP damage-repair signaling pathway. Therefore, inhibition of poly(adenosine diphosphate (ADP)-ribose) polymerase (PARP) has the potential to increase PDT efficacy. This work reports on the synthesis of a controlled release system of a photosensitizer, methylene blue (MB) and a PARP-inhibitor, the veliparib. MB and veliparib were co-encapsulated in poly(lactic-co-glycolic acid) (PLGA) nanoparticles (VMB-NPs). A colloidal stable aqueous suspension of nanoparticles was obtained. The average hydrodynamic diameter was 90 nm and a narrow size distribution was obtained, with a polydispersity index (PDI) of 0.08. The release kinetics of MB and veliparib from VMB-NPs showed an initial burst of 8.7% and 58.3% release of the total amounts of MB and veliparib respectively, in the first 6 h, and a delayed release of up to 11.3% and 70%, in 19 days, for MB and veliparib, respectively. The VMB-NPs showed no cytotoxicity in the dark but the viability of B16F10-Nex2 cells decreased by 36% when the cells were irradiated (102 J/cm2, 660 nm) and treated with VMB-NPs containing 1.0 µM of MB and 8.3 µM of veliparib. Considering the increased photoactivity even at low MB and veliparib concentrations and the absence of cytotoxicity in dark, the co-encapsulation of MB and veliparib was shown to be a promising strategy to improve the PDT efficacy.

ZnO nanoparticles having spherical and rod shapes with high crystallinity and uniform average crystallite sizes were prepared by a new route named the glycerol–urea (GU) route. The syntheses were carried out using Zn(NO3)2·6H2O and NaOH in a 3 : 1 mol ratio of G : U solution under stirring at 70 °C. These reactions took less than 1 hour to completion with a high mass yield. NaCl and LiCl salts were added to attempt to modulate crystallites morphology and size. The effect of LiCl led to smaller spherical particles with an average size of 11(2) nm, whereas NaCl resulted in rod-shaped ZnO nanoparticles having an average length of 44(7) nm and an average diameter of 12(2) nm; whereas GU synthesis (no salt) led to 19(3) nm nanoparticles. Detailed X-ray powder diffraction, FT-IR and UV-Vis analyses confirmed the typical wurtzite structure of the particles. Electron microscopy images (SEM and TEM) showed the morphology and size of the ZnO nanoparticles. Photoluminescence revealed different behaviors related to defects and exciton emission.

In this study, poly(N-vinylcaprolactam-co-acrylic acid) (poly(NVCL-co-AA)) containing 20 and 30 mol% AA, were used to prepare thermo-and-pH-sensitive fibers containing a hydrophobic drug, ketoprofen, via electrospinning. Ketoprofen entrapment efficiency was assessed via UV–visible spectroscopy and revealed high values. The interaction drug/copolymer was investigated by FTIR, which indicated the drug entrapment into the fibers. The crystallinity of the ketoprofen-loaded fibers evaluated via DSC confirmed the presence of ketoprofen in its amorphous phase. Cytotoxicity of ketoprofen-loaded fibers was evaluated by cell viability assays using MTT. The results showed that the copolymer was not cytotoxic at a low ketoprofen concentration. The ketoprofen release profile was analyzed using independent and model-dependent approaches and showed slow-release rates at high temperatures. The study of the drug release mechanism showed that the Korsmeyer–Peppas model fits to the release behavior. These findings may expand poly(NVCL-co-AA) application making them promising candidates for temperature and pH responsive drug delivery systems.

The increasing incidence of diseases caused by the harmful effects of UV radiation in skin, predominantly skin cancer, induce the search for more efficient photoprotector agents. Nowadays, titanium dioxide (TiO2) and zinc oxide (ZnO) are the most widely used photoprotectors and therefore form the main components of commercially available sunscreens. Although the outstanding efficiency in absorbing and scattering UV radiation, mainly as nanoparticles, recent studies have raised concerns regarding the safe use of these nanoparticles, especially due to their high generation of reactive oxygen species (ROS). Thereby, this work focus on the evaluation of the photoprotective activity of zirconia nanoparticles (ZrO2 NPs) and their cytotoxicity study in the presence and absence of UV irradiation. The ZrO2 NPs were synthesized by hydrothermal method and their hydrodynamic diameter, Zeta potential and colloidal stability were characterized by dynamic light scattering. The morphology and size were observed by transmission electron microscopy. The synthesis resulted in ZrO2 NPs with 50 nm of diameter and 56 nm of hydrodynamic diameter. The high colloidal stability was evidenced by the high value of Zeta potential (+48 mV) and low polydispersity index (0.09). The UV–vis spectrum of the ZrO2 NPs in aqueous suspension showed an intense light scattering below 250 and a wide absorption band at 285 nm. The poor generation of ROS by ZrO2 NPs was confirmed by the absence of photodegradation of methylene blue after long periods of irradiation. The in vitro assays performed with HaCaT cell line showed that the cell viability did not decrease in the absence of irradiation. However, after 24 h of incubation, the cell viability decreased under UV-irradiation in comparison with irradiated cells that were not incubated with ZrO2 NPs. Notably, in these assays, the cells were incubated with the ZrO2 NPs and after 24 h, they were replaced by fresh culture medium before the cell viability assay. Nevertheless, another in vitro assay was performed in order to evaluate the photoprotective activity of ZrO2 NPs. The cells were irradiated in the presence of ZrO2 NPs suspension. In this case, cell viability did not decrease even after long period of UV-irradiation and at higher concentration of ZrO2 NPs. The present results showed that ZrO2 NPs could be an interesting material to be used for skin photoprotection since they showed low cytotoxicity, absence of ROS generation and protection under UV irradiation. Additionally, the ZrO2 NPs suspension was transparent as usually required for applications in sunscreens.

Diamond-like carbon (DLC) films have been extensively applied as a solid lubricant and as a protective coating due to their attractive chemical, mechanical, and tribological properties. Furthermore, these properties of DLC coatings can be improved with the incorporation of nanoparticles of different materials, especially diamond nanoparticles (DNPs). Herein, the incorporation of chemical vapor deposition (CVD) DNPs was done from a deionized aqueous colloidal solution by using a controlled pulsed valve, which is an innovative aspect of this work. The CVD DNPs were pulverized into the plasma region and incorporated in the DLC films bulk with controllable size particle distribution and density. In addition, an enhanced process to obtain DNPs with suitable size distribution was established by using a high energy ball milling technique, centrifugation, and a special chemical cleaning process. The DLC films were deposited on a metallic substrate via a modified, pulsed DC plasma-enhanced chemical vapor deposition (PECVD) technique, with an additional cathode. X-ray diffractometry (XRD) and scanning electronic microscopy (SEM) techniques showed that an aqueous colloidal solution of high-purity DNPs with a mean diameter of 32 nm was obtained. Dynamic light scattering (DLS) results showed that it is possible to control particle size distribution by varying the milling and centrifugation time lengths. Therefore, a valuable result was that DLC films could be deposited with DNPs by using clean water without affecting deposition rate, the adhesion between the DLC films and substrates, the structural quality of the film, and keeping lower coefficient of friction.

Made available in DSpace on 2020-12-10T17:27:38Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-03-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Nanodiamonds (NDs) are amongst the most investigated carbon-based nanostructures due to their chemical stability and favorable mechanical properties. Despite the number of works on methods for NDs production, one of the main challenges is to achieve their colloidal stability in aqueous suspension. Additionally, NDs are normally obtained by expensive, complex and time-consuming process. Herein, it was presented a facile method to obtain NDs in aqueous suspension by using columnar structure diamond from Hot-Filament Chemical Vapour Deposition reactor (HFCVD). CVD diamond leftover thick film from CVDVale Company was used. Therefore, this method has the advantage of being not only practical but also cost-effective since it brings a profitable use of CVD diamond leftover. The Diamond thick film was submitted to ultrasonic cavitation in the presence and absence of ZrO2 microbeads in aqueous medium. The NDs hydrodynamic diameter and the stability in aqueous suspension were monitored by light scattering, size and morphology were analyzed by transmission electronic microscopy. Considering the wide application of NDs in biomedical devices, cytotoxicity of aqueous suspensions of NDs was evaluated against murine embryonic fibroblast cells. Furthermore, NDs were functionalized with hydrogen and carboxyl groups. NDs aqueous suspension of straight size distribution was obtained even in the absence of ZrO2 beads, indicating that they may be dispensable in order to decrease NDs size. NDs of average hydrodynamic diameter of 22 nm and -35 mV of Zeta-potential were obtained after ultrasonic cavitation followed by 2 h of centrifugation, not demonstrating cytotoxicity to cells at very low (0.05-0.5 mu g/mL) nor at higher concentrations (116 mu g/mL). Nevertheless, NDs showed a moderate cytotoxicity at intermediary concentration range (0.5-2.2 mu g/mL). From our knowledge, this is the first work that reports on a facile method for providing NDs aqueous suspension with high colloidal stability from HFCVD diamond leftover. Fed Univ Sao Paulo UNIFESP, Inst Sci & Technol, Nanomat & Nanotoxicol Lab, Talim 330, BR-12231280 Sao Jose Dos Campos, SP, Brazil Fed Inst Sao Paulo IFSP, Rod Pres Dutra,Km 145, BR-12223201 Sao Jose Dos Campos, SP, Brazil Natl Inst Space Res INPE, Sensors & Mat Associated Lab, Av Astronautas 1-758, BR-12227010 Sao Jose Dos Campos, SP, Brazil Inst Aeronaut & Space IAE, Aerosp Sci & Technol Dept, Praca Marechal Eduardo Gomes 50, BR-12228900 Sao Jose Dos Campos, SP, Brazil Technol Inst Aerocaut ITA, Fundamental Sci Div, Praca Marechal Eduardo Gomes 50, BR-12228900 Sao Jose Dos Campos, SP, Brazil Sao Paulo State Univ UNESP, Inst Sci & Technol, Rod Pres Dutra,Km 137,8 Eugenio Melo, BR-12247004 Sao Jose Dos Campos, SP, Brazil Sao Paulo State Univ UNESP, Inst Sci & Technol, Rod Pres Dutra,Km 137,8 Eugenio Melo, BR-12247004 Sao Jose Dos Campos, SP, Brazil FAPESP: 2017/01697-6 FAPESP: 2012/15857-1

Microbial biofilms, structured communities of microorganisms, have been often associated to the infection and bacterial multiresistance problem. Conventional treatment of infection involves the use of antibiotics, being an alternative approach is the use of red propolis, a natural product, to prepare polymer nanoparticles. The aim of the present study was to encapsulate red propolis extract in poly(lactic-co-glycolic acid) (PLGA) nanoparticles for destruction in vitro of pathogenic biofilms. Poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs) containing red propolis hydroethanolic extract (2 mg/mL) were produced by emulsification solvent diffusion method. The extract and developed nanoparticles were analyzed for antimicrobial activity and inhibition of bacterial biofilm formation in vitro against Staphylococcus aureus and Pseudomonas aeruginosa. Transmission electron microscopy images confirmed spherical nanoparticles in the range size from 42.4 nm (PLGA NPs) to 69.2 nm (HERP PLGA NPs), with encapsulation efficiencies of 96.99%. The free extract and encapsulated in polymer nanoparticle presented antimicrobial potential, with a minimum inhibitory concentration from 15.6 to 125 μg mL−1 and from 100 to 1560 μg mL−1 to inhibit biofilm formation for the Staphylococcus aureus and Pseudomonas aeruginosa, respectively.

© King Abdulaziz City for Science and Technology 2020, The emergence of bacterial resistance due to the indiscriminate use of antibiotics warrants the need for developing new bioactive agents. In this context, antimicrobial peptides are highly useful for managing resistant microbial strains. In this study, we report the isolation and characterization of peptides obtained from the venom of the toadfish Thalassophryne nattereri. These peptides were active against Gram-positive and Gram-negative bacteria and fungi. The primary amino acid sequences showed similarity to Cocaine and Amphetamine Regulated Transcript peptides, and two peptide analogs—Tn CRT2 and Tn CRT3—were designed using the AMPA algorithm based on these sequences. The analogs were subjected to physicochemical analysis and antimicrobial screening and were biologically active at concentrations ranging from 2.1 to 13 μM. Zeta potential analysis showed that the peptide analogs increased the positive charge on the cell surface of Grampositive and Gram-negative bacteria. The toxicity of Tn CRT2 and Tn CRT3 were analyzed in vitro using a hemolytic assay and tetrazolium salt reduction in fibroblasts and was found to be significant only at high concentrations (up to 40 μM). These results suggest that this methodological approach is appropriate to design novel antimicrobial peptides to fight bacterial infections and represents a new and promising discovery in fish venom., This research was supported by FAPESP grant No. 2017/00032-0.

Made available in DSpace on 2020-12-12T01:27:42Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Over the past few years, several tridimensional synthetic bone grafts, known as scaffolds, are being developed to overcome the autologous grafts limitations. Among the materials used on the production of scaffolds, the 45S5 bioglass stands out due to its capacity of bonding to hard and soft tissues. Silver nanoparticles are well-known for their antimicrobial properties and their incorporation on the scaffold may promote its antimicrobial response, avoiding microorganism proliferation on the materials surface. This study proposes a simple way to coat 45S5 bioglass-based scaffolds with silver nanoparticles. The scaffolds were obtained by the sponge replication technique and the silver nanoparticles were incorporated by soaking under ultrasonic stirring. The antimicrobial activity of the scaffolds was analyzed against three different microbial strains: S. aureus, P. aeruginosa, and C. albicans. Due to the heat treatment during the scaffold production, the bioglass crystalized mainly in a sodium calcium silicate phase, forming a glass–ceramic scaffold. The silver nanoparticles were coated in a well-distributed manner throughout the scaffold, while avoiding their aggregation. The coated scaffold inhibited the growth of all the analyzed microorganism. Therefore, the use of ultrasonic stirring to coat the bioglass scaffold with silver nanoparticles showed to be an efficient way to promote its antimicrobial response. Bioceramics Laboratory Science and Technology Institute UNIFESP Nanomaterials and Nanotoxicology Laboratory Science and Technology Institute UNIFESP IFSP Science and Technology Institute UNESP Plasmas and Processes Laboratory ITA Science and Technology Institute UNESP

Although Photodynamic Therapy (PDT) of cancer has been continuously improved, its efficiency is still limited by the high toxicity in the absence of irradiation, aggregation and deactivation by biomolecules of the most common photosensitizers (PS). The association of PS to nanoparticles (NPs) can be a promising tool to overcome these limitations and also to enhance PS tumoral selectivity. In addition, the association of PS to metallic NPs may provide the modulation of PS fluorescence and also the enhancement of PS photoactivity due to the electronic coupling with NPs plasmon effect. Adversely to the innumerous work on the coupling of PS to metallic NPs, the application of bimetallic NPs with this goal has not been explored yet. In this work we investigated the physicochemical properties and cytotoxicity of bimetallic gold-platinum NPs (AuPt NPs) conjugated to a chlorin molecule modified with a thiol group. Additionally, chlorin was coupled to AuNPs for comparative purposes since these have been the most commonly used NPs in PDT. The results showed that both platforms promoted the chlorin solubility in water which is crucial in biological applications. Despite the enhancement of photoactivity promoted by both NPs in comparison with chlorin in solution, chlorin-conjugated with AuPtNPs proved to be a more suitable platform for PDT application, since it showed a lower dark citotoxicity, as well as a higher generation of singlet oxygen and cell internalization compared with chlorin-conjugated AuNPs. It is important to highlight that this is the first work reporting on the enhancement of PS photoactivity by its conjugation to AuPtNPs.

Despite the potential antimicrobial activity of metallic nanoparticles, the increasing concerns about nanosafety have been holding back the use of these materials in therapeutics and biomedical devices. In the last years, several studies called attention to metallic nanoparticles toxicity. In the most part of in vitro studies performed with mammalian cells, metallic NPs reduced cell viability and induced genotoxicity and inflammatory responses. Bimetallic NPs have attracted great attention because they present distinct and even more advanced characteristics when compared to nanoparticles formed by a single metal. Recently, bimetallic NPs have emerged as an alternative to improve the antimicrobial activity of metallic nanoparticles, aiming at the broadening of the action spectrum and the reduction of the toxicity. However, the biocompatibility of bimetallic nanoparticles has been demonstrated only by in vitro studies. In the present work, the toxicity of AuPt nanoparticles was addressed both in vitro and in vivo. In addition, the antimicrobial activity of AuPt bimetallic nanoparticles has been evaluated in comparison with Au and Ag nanoparticles. The nanoparticles were characterized by ultraviolet-visible spectroscopy, dynamic light scattering, transmission electron microscopy, inductively coupled plasma optical emission spectroscopy, and X-ray diffraction. The antimicrobial activity was studied against Candida albicans, Pseudomonas aeruginosa, and Staphylococcus aureus. The toxicity of nanoparticles was evaluated in vitro by analyzing their toxicity against human fibroblast cells (HS68 cell line) and in vivo by embryonic toxicity test in zebrafish (Danio rerio). The results confirmed the intrinsic antimicrobial activity of the three types of nanoparticles but different toxicity. Bimetallic nanoparticles showed enhanced antimicrobial activity in comparison with Au nanoparticles but lower antimicrobial activity compared with Ag nanoparticles. However, AuPt nanoparticles showed great advantage over Ag nanoparticles due to the absence of cytotoxicity and lower toxicity in vivo.

Conjugation of photosensitizers (PS) with nanoparticles has been largely used as a strategy to stabilize PS in the biological medium resulting in photosensitizing nanoparticles of enhanced photoactivity. Herein, (Meso-5, 10, 15, 20-tetrakis (3-hydroxyphenyl) phorphyryn (mTHPP) was conjugated with diamond nanoparticles (ND) by covalent bond. Nanoconjugate ND-mTHPP showed suitable stability in aqueous suspension with 58 nm of hydrodynamic diameter and Zeta potential of −23 mV. The antibacterial activity of ND-mTHPP was evaluated against Escherichia coli for different incubation times (0–24 h). The optimal activity was observed after 2 h of incubation and irradiation (660 nm, 51 J/cm2) performed right after the addition of ND-mTHPP (100 μg/mL) to the bacterial suspension. The inhibitory activity was 56% whereas ampicillin at the same conditions provided only 14% of bacterial growth inhibition. SEM images showed agglomerate of ND-mTHPP adsorbed on the bacterial cell wall, suggesting that the antimicrobial activity of ND-mTHPP was afforded by inducing membrane damage. Cytotoxicity against murine embryonic fibroblast cells (MEF) was also evaluated and ND-mTHPP was shown to be noncytotoxic since viability of cells cultured for 24 h in the presence of the nanoconjugate (100 μg/mL) was 78%. Considering the enhanced antibacterial activity and the absence of cytotoxic effect, it is possible to consider the ND-mTHPP nanoconjugate as promising platform for application in antimicrobial photodynamic therapy (aPDT).

Electroactive nanofibers based on thermoplastic polyurethane (TPU) and poly (alkoxy anilines) produced by electrospinning has been explored for biomaterials applications. The thermoplastic polyurethane is a biocompatible polymer with good mechanical properties. The production of TPU nanofibers requires the application of high voltage during electrospinning in order to prepare uniform mats due to its weak ability to elongate during the process. In order to overcome this limitation, a conductive polymer can be incorporated to the process, allowing generates mats without defects. In this work, poly (o-ethoxyaniline) POEA doped with dodecylbenzene sulfonic acid (DBSA) was blended with thermoplastic polyurethane (TPU) by solution method. Films were produced by casting and nanofibers were prepared by electrospinning. The effect of the POEA on morphology, distribution of diameter and cell viability of the nanofibers was evaluated. The results demonstrated that the incorporation of POEA in TPU provided to the mats a suitable morphology for cellular growth. This article is protected by copyright. All rights reserved.

Titanate nanorod synthesis method is extremely important due to their large application in electronic, catalysis, and biological areas. However, works reporting the influence of synthesis parameters on the structure, morphology, and properties of titanate nanorods are still rare. Therefore, this work aims to analyze the preparation of titanate nanorods from TiO2 nanoparticles via hydrothermal reaction. The microstructure and morphological properties were evaluated as a function of time, temperature and precursor nature (anatase or anatase/rutile mixture) by X-ray powder diffraction, Raman spectroscopy, transmission electron microscopy and field-emission scanning electron microscopy. The crystallinity of the precursor was the main parameter for the titanate nanorods formation. Besides, temperature has also a direct influence in the fibril morphology. The use of low temperature and anatase/rutile mixture was not able to produce titanate nanorods. Only the use of higher temperatures and pure anatase resulted in rod-like titanates, which showed higher methylene blue photodegradation efficiency than TiO2 nanoparticles.

Antibody-derived peptides modulate functions of the immune system and are a source of anti-infective and antitumor substances. Recent studies have shown that they comprise amino acid sequences of immunoglobulin complementarity-determining regions, but also fragments of constant regions. VH CDR3 of murine mAb AC-1001 displays antimetastatic activities using B16F10-Nex2 murine melanoma cells in a syngeneic model. The peptide was cytotoxic in vitro in murine and human melanoma cells inducing reactive oxygen species (ROS) and apoptosis by the intrinsic pathway. Signs of autophagy were also suggested by the increased expression of LC3/LC3II and Beclin 1 and by ultrastructural evidence. AC-1001 H3 bound to both G- and F-actin and inhibited tumor cell migration. These results are important evidence of the antitumor activity of Ig CDR-derived peptides.

Polyblends of an electroactive biomaterial consisting of a biodegradable polyester – PHBV and a carboxylate polythiophene derivative, the poly(3-thiophene ethyl acetate) – PTAcEt have been prepared and applied as a substrate for tissue engineering. The biodegradable polymer was used as a matrix for polythiophene. Thermal, electrical, optical and morphological properties as well as viability and cell adhesion (in vitro assays) were investigated. Blend films exhibited high flexibility, resistance to handling and a semiconducting character, since they preserved the individual properties of each polymer. Besides, the incorporation of PTAcEt (up to 12%) has led to improvements in the thermal stability and in the crystallinity degree of the bioactive matrix. Qualitative morphological analysis showed irregular and porous surfaces; important features for growth and cell adhesion. Viability assays indicated that the polyblends promoted superior cell proliferation after 72 h exposure to mammalian cells when compared to a pure PHBV matrix. Therefore, PTAcEt showed low cytotoxicity allowing cell growth. The adhesion study revealed that the cells were able to adhere to the surface and proliferate inside the cavities of the substrate. The results indicate that the 88 : 12% (PHBV : PTAcEt) blend is a promising candidate for use as scaffold in the biomedical area.

In this work, graft copolymerization of n-butyl acrylate (BA) with methyl methacrylate (MMA) onto enzymatically hydrolyzed cationic cassava starch (CCS) was carried out in a semi-batch emulsion polymerization and the latexes were used as a binder for paper sizing agent. The purpose of this work was to substitute a portion of the BA/MMA by CCS (from 0 to 20 wt.%) in the copolymer and to investigate the consequent effects on the properties of the latex, films and coated paper (e.g., colloidal properties, cytotoxicity and water absorption). Cytotoxicity of polymer films, CCS and α-amylase was evaluated in human keratinocytes cells (HaCaT) for 24 and 96 h. The results show that the grafting efficiency decreased as the concentration of CCS increased. Nuclear magnetic resonance (1H-NMR) and Fourier transform infrared spectroscopy (FT-IR) analyses revealed successful grafting copolymerization of BA and MMA onto CCS. Polymer films and CCS solutions were not cytotoxic towards HaCaT cells until 24 h of incubation. Nevertheless, after 96 h of incubation, cell viability was below 70 %, which is an indication that the polymer films with 10 and 20 wt.% of CCS were cytotoxic after longer incubation times. The cell viability was lower as the concentration of CCS in the film increased. Water absorption of polymer films and coated paper showed a direct relationship with respect to both the content of CCS employed and the grafting efficiency. These results demonstrate the utility of enzymatically hydrolyzed cationic starch-graft-polymer as coating binders and as sizing agents for the paper and packing industry.

The high hydrophilicity of cellulose nanocrystals (CNC) may result in poor dispersion in some matrices and solvents. So in this work, two different methodologies were used to reduce the hydrophilicity of CNC. In the first methodology, CNC were acetylated (CNC-Ac) in a mixture of acetic and hydrochloric acid, and in the second methodology, polyethylene glycol (PEG) was adsorbed onto CNC surface (CNC-PEG) under stirring in aqueous solution. CNC obtained by both methods were characterized by transmission electron microscopy (TEM), infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), zeta potential, and thermogravimetric analysis (TGA). Images of TEM showed that the intrinsic morphology of cellulose was preserved after both treatments. FTIR confirmed acetylation reaction by the presence of a new band at 1732 cm−1 (acetate groups) and the consumption of OH groups. XRD showed a reduction in the crystallinity index for both applied methodologies. DLS showed reduced stability in water for CNC-Ac and CNC-PEG. Values of zeta potential changed after acetylation, from − 45 mV (CNC) to − 1 mV (CNC-Ac), and after adsorption of PEG, to − 26.7 mV (CNC-PEG). TGA showed a reduction in the thermal stability after both treatments and a change in the main degradation behavior for CNC-PEG. MTT assays showed that both proposed functionalizations induce cell proliferation, being even more evident for acetylation because, in addition to viability increase with time, it increased with the sample concentration.

Although several researchers had reported on methodologies for surface plasmon resonance (SPR) signal amplification based on the use of nanoparticles (NPs), the majority addressed the sandwich technique and low protein concentration. In this work, a different approach for SPR signal enhancement based on the use of gold NPs was evaluated. The method was used in the detection of two lectins, peanut agglutinin (PNA) and concanavalin A (ConA). Gold NPs were functionalized with antibodies anti-PNA and anti-ConA, and these NPs were used as protein scavengers in a solution. After being incubated with solutions of PNA or ConA, the gold NPs coupled with the collected lectins were injected on the sensor containing the immobilized antibodies. The signal amplification provided by this method was compared to the signal amplification provided by the direct coupling of PNA and ConA to gold NPs. Furthermore, both methods, direct coupling and gold NPs as protein scavengers, were compared to the direct detection of PNA and ConA in solution. Compared to the analysis of free protein, the direct coupling of PNA and ConA to gold NPs resulted in a signal amplification of 10–40-fold and a 13-fold decrease of the limit of detection (LOD), whereas the use of gold NPs as protein scavengers resulted in an SPR signal 40–50-times higher and an LOD 64-times lower.

Pristine multiwalled carbon nanotubes (P-MWCNTs) were functionalized with carboxylic groups (MWCNT-COOH) through oxidation reactions and then reduced to produce hydroxyl groups (MWCNT-OH). Pristine and functionalized MWCNTs were used to produce poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) nanocomposites with 0.5 wt% of MWCNTs. MWCNT functionalization was verified by visual stability in water, infrared and Raman spectroscopy, and zeta potential measurements. Pristine and functionalized MWCNTs acted as the nucleating agent in a PHBV matrix, as verified by differential scanning calorimetry (DSC). However, the dispersion of filler into the matrix, thermal stability, and direct current (DC) conductivity were affected by MWCNT functionalization. Scanning electron microscopy (SEM) showed that filler dispersion into the PHBV matrix was improved with MWCNT functionalization. The surface roughness was reduced with the addition and functionalization of MWCNT. The thermal stability of PHBV/MWCNT-COOH, PHBV/P-MWCNT, and PHBV/MWCNT-OH nanocomposites were 20, 30, and 30 °C higher than neat PHBV, respectively, as verified by thermogravimetry analysis (TGA). Addition of pristine and functionalized MWCNTs provided electrical conductivity in nanocomposite, which was higher for PHBV/P-MWCNTs (1.2 × 10−5 S cm−1).

Lipid coating is a method highly used to improve the biocompatibility of nanoparticles (NPs), even though its effect on the NP properties is still object of investigation. Herein, silica NPs containing methylene blue, which is a photosensitizer used in a variety of biomedical applications, were coated with a phospholipid bilayer. Regarding the photophysical properties, lipid-coating did not cause significant changes since bare and lipid-coated NPs presented very similar absorption spectra and generated singlet oxygen with similar efficiencies. However, NP interaction with cells and membrane mimics was totally different for bare and lipid-coated NPs. Lipid-coated NPs were distributed through the cell cytoplasm whereas bare NPs were detected only in some vacuolar regions within the cells. Since cellular uptake and cytolocalization are influenced by NP adsorption on cell membranes, the interaction of lipid-coated and bare NPs were studied on a membrane mimic, i.e., Hybrid Bilayer Membranes (HBMs) made of different compositions of negatively charged and neutral lipids. Interactions of bare and lipid-coated NPs with HBMs were analyzed by Surface Plasmon Resonance Imaging. Bare NPs presented high adsorption and aggregation on HBMs independently of the surface charge. Conversely, lipid-coated NPs presented less aggregation on the membrane surface and the adsorption was dependent on the charges of the NPs and of the HBMs. Our results indicated that NPs aggregation on the membrane surface can be modulated by lipid coating, which affects the cytosolic distribution of the NPs.

In this work, chitosan hydrogels crosslinked with genipin and reinforced with cellulose nanocrystals (CNC) were developed and characterized with the aim of future biomedical applications. CNC was produced by acid hydrolysis and characterized by atomic force microscopy (AFM). Chitosan/CNC nanocomposite hydrogels were produced with different CNC concentrations (w/w): 0%, 2%, 4%, and 6%. The genipin was used as a crosslinking agent in a genipin/chitosan molar proportion of 1:8. The hydrogels were characterized by porosity measurements, scanning electron microscopy (SEM), swelling test, and mechanical compression test. No significant differences were observed concerning the porosity of the hydrogels, however, a trend of decreasing porosity was observed with increasing CNC content. The SEM images showed a better pore structure as the CNC concentration increased. A decrease in the swelling degree with increasing CNC content in the chitosan/CNC nanocomposite hydrogel was verified in the swelling tests. An increase in the CNC concentration in the chitosan/CNC nanocomposite hydrogel caused a gradual increase in the maximum stress and maximum strain as observed in the compression tests, showing a significant difference between chitosan/CNC 6 wt % and neat chitosan hydrogel.

Electroactive nanofibers based on thermoplastic polyurethane (TPU) and poly(alkoxy anilines) produced by electrospinning has been explored for biomaterials applications. The thermoplastic polyurethane is a biocompatible polymer with good mechanical properties. The production of TPU nanofibers requires the application of high voltage during electrospinning in order to prepare uniform mats due to its weak ability to elongate during the process. To overcome this limitation, a conductive polymer can be incorporated to the process, allowing generates mats without defects. In this study, poly(o-ethoxyaniline) POEA doped with dodecylbenzene sulfonic acid (DBSA) was blended with thermoplastic polyurethane (TPU) by solution method. Films were produced by casting and nanofibers were prepared by electrospinning. The effect of the POEA on morphology, distribution of diameter and cell viability of the nanofibers was evaluated. The results demonstrated that the incorporation of POEA in TPU provided to the mats a suitable morphology for cellular growth. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 601-607, 2017.

Image-guided radiation treatments (IGRT) routinely utilize radio-opaque implantable devices, such as fiducials or brachytherapy spacers, for improved spatial accuracy. The therapeutic efficiency of IGRT can be further enhanced by biological in situ dose painting (BIS-IGRT) of radiosensitizers through localized delivery within the tumor using gold fiducial markers that have been coated with nanoporous polymer matrices loaded with nanoparticles (NPs). In this work, two approaches were studied: (i) a free drug release system consisting of Doxorubicin (Dox), a hydrophilic drug, loaded into a non-degradable polymer poly(methyl methacrylate) (PMMA) coating and (ii) poly(d,l-lactic-co-glycolic acid) (PLGA) NPs loaded with fluorescent Coumarin-6, serving as a model for a hydrophobic drug, in a biodegradable chitosan matrix. Temporal release kinetics measurements in buffer were carried out using fluorescence spectroscopy. In the first case of free Dox release, an initial release within the first few hours was followed by a sustained release over the course of the next 3 months. In the second platform, release of NPs and the free drug was controlled by the degradation rate of the chitosan matrix and PLGA. The results show that dosage and rate of release of these radiosensitizers coated on gold fiducials for IGRT can be precisely tailored to achieve the desired release profile for radiation therapy of cancer.

To characterize and evaluate chitosan film containing PLGA nanoparticles (NPs) as a platform for localized dual-drug release.Fluorescent Paclitaxel (FPTX), a hydrophobic drug, was incorporated into PLGA NPs. FPTX-loaded PLGA NPs and Carboxyfluorescein (CF), a hydrophilic model drug, were embedded into chitosan films. Release of CF and NPs from chitosan and release of FPTX from PLGA NPs were monitored by fluorescence. The stability of the platform was observed through SEM and dynamic light scattering (DLS).Chitosan films containing CF and FPTX-loaded PLGA NPs showed a biphasic release profile. In the first phase, 78% of CF and 34% of NPs were released within few days. In the second phase, the release was slower, showing an additional release of 22% of CF and 18% of NPs after 3 weeks. SEM images and DLS measurements showed that NP release depends on film degradation rate. FPTX-loaded PLGA NPs showed the release of 19.8% of total drug in 2 days, and no additional release was detected in the next 26 days.The ability of chitosan film containing PLGA NPs to coat gold surface and to incorporate and release two different drugs of different hydrophilicity make it a promising platform for localized dual-drug release.

One of the most important challenges in tissue engineering research is the development of biomimetic materials. In this present study, we have investigated the effect of the titanium dioxide (TiO2 ) nanoparticles on the properties of electrospun mats of poly (hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), to be used as scaffold. The morphology of electrospun fibers was observed by scanning electron microscopy (SEM). Both pure PHBV and nanocomposites fibers were smooth and uniform. However, there was an increase in fiber diameter with the increase of TiO2 concentration. Thermal properties of PHBV and nanocomposite mats were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). DSC analysis showed that the crystallization temperature for PHBV shifts to higher temperature in the presence of the nanoparticles, indicating that TiO2 nanoparticles change the process of crystallization of PHBV due to heterogeneous nucleation effect. TGA showed that in the presence of the nanoparticles, the curves are shifted to lower temperatures indicating a decreasing in thermal stability of nanocomposites compared to pure PHBV. To produce scaffolds for tissue engineering, it is important to evaluate the biocompatibility of the material. Cytotoxicity assay showed that TiO2 nanoparticles were not cytotoxic for cells at the concentration used to synthesize the mats. The proliferation of cells on the mats was evaluated by the MTT assay. Results showed that the nanocomposite samples increased cell proliferation compared to the pure PHBV. These results indicate that continuous electrospun fibrous scaffolds may be a good substrate for tissue regeneration.

Herein, we report on the synthesis of photosensitizing nanoparticles in which the generation of different oxidizing species, i.e., singlet oxygen (1O2) or radicals, was modulated. Sol gel and surface chemistry were used to obtain nanoparticles with specific ratios of dimer to monomer species of phenothiazine photosensitizers (PSs). Due to competition between the reactions involving electron transfer within dimer species and energy transfer from monomer triplets to oxygen, the efficiency of 1O2 generation could be controlled. Nanoparticles with an excess of dimer have an 1O2 generation efficiency (S(delta)) of 0.01 while those without dimer have a S(delta) value of 0.4. Furthermore, we demonstrate that the PS properties of the nanoparticles are not subjected to interference from the external medium as is commonly the case for free PSs, i.e., PS ground and triplet states are not reduced by NADH and ascorbate, respectively, and singlet excited states are less suppressed by bromide. The modulated 1O2 generation and the PS protection from external interferences make this nanoparticle platform a promising tool to aid in performing mechanistic studies in biological systems. Also, it offers potential application in technological areas in which photo-induced processes take place.

We present the preparation and characterization of methylene blue-containing silica-coated magnetic particles. The entrapment of methylene blue (MB), a photodynamic therapy drug under study in our group, in the silica matrix took place during the growth of a silica layer over a magnetic core composed of magnetite nanoparticles. The resulting material was characterized by transmission electron microscopy (TEM), light scattering, and X-ray diffraction. It is composed of approximately 30 nm silica spheres containing magnetic particles of 11 +/- 2 nm and methylene blue entrapped in the silica matrix. The immobilized drug can generate singlet oxygen, which was detected by its characteristic phosphorescence decay curve in the near-infrared and by a chemical method using 1,3-diphenylisobenzofuran to trap singlet oxygen. The lifetime of singlet oxygen was determined to be 52 micros (in acetonitrile) and 3 micros (in water), with both values being in good agreement with those in the literature. The release of singlet oxygen (etaDelta) was affected by the encapsulation of MB in the silica matrix, which caused a reduction to 6% of the quantum yield of MB free in solution. The magnetization curve confirmed the superparamagnetic behavior with a reduced saturation magnetization in respect to uncoated magnetic nanoparticles, which is consistent with the presence of a diamagnetic component over the magnetite surface. The result is a single particle platform that combines therapy (photosensitizer) and diagnostic (MRI contrast agent) possibilities at the same time, as well as drug targeting.

The association of PhotoSensitizer (PS) molecules with nanoparticles (NPs) forming photosensitizing NPs, has emerged as a therapeutic strategy to improve PS tumor targeting, to protect PS from deactivation reactions and to enhance both PS solubility and circulation time. Since association with NPs usually alters PS photophysical and photochemical properties, photosensitizing NPs are an important tool to modulate ROS generation. Depending on the design of the photosensitizing NP, i.e., type of PS, the NP material and the method applied for the construction of the photosensitizing NP, the deactivation routes of the excited state can be controlled, allowing the generation of either singlet oxygen or other reactive oxygen species (ROS). Controlling the type of generated ROS is desirable not only in biomedical applications, as in Photodynamic Therapy where the type of ROS affects therapeutic efficiency, but also in other technological relevant fields like energy conversion, where the electron and energy transfer processes are necessary to increase the efficiency of photoconversion cells. The current review highlights some of the recent developments in the design of Photosensitizing NPs aimed at modulating the primary photochemical events after light absorption.

In the search of new photoactive species that may be of use either in energy conversion or in photodynamic therapy, we studied the functionalization of silicon (1 0 0) with thionin using the glutaraldehyde coupling reaction. Surface properties were obtained by ellipsometric measurements, atomic force microscopy, and luminescence spectroscopy, which indicated the formation of a well organised monolayer in the silicon surface. In addition, the comparison of Raman spectroscopy data with first-principles pseudopotential calculations of the vibrational modes of the thionin molecule also indicate the formation of a monolayer of intact thionin molecules. Therefore, the simple functionalization process (involving only mild aqueous solution chemistry) described here works well and can be used to construct smooth monolayers of photoactive molecules with functional amine groups.

Bioactive materials (having an amino acid, Ac-Tryptophan, A or a peptide, Ac-Trp-Ala-Ala, B) were anchored onto silica particles. A photoactive linker (N,N′-bis(2-phosphonoethyl)-1,4,5,8-naphthalenediimide (DPN)) was initially attached to the particles and next the amino acids were bound by using both Zr/P chemistry and 1,3-diisopropylcarbodiimide/1-hydroxybenzotriazole coupling. In A derivative extensive complexation of Trp with DPN was observed. Photolysis studies showed the presence of excited state reactions on the silica particles, moreover the radical species (DPN.−, TrpH.+, Trp.) remained alive ∼100 times longer on the particle surface than in solution. These studies show that the formation rate of these radicals is a function of the supramolecular structures of the peptide and of the amino acid derivative on the silica particle.

Methylene blue (MB) is a molecule that has been playing important roles in microbiology and pharmacology for some time. It has been widely used to stain living organisms, to treat methemoglobinemia, and lately it has been considered as a drug for photodynamic therapy (PDT). In this review, we start from the fundamental photophysical, photochemical and photobiological characteristics of this molecule and evolved to show in vitro and in vivo applications related to PDT. The clinical cases shown include treatments of basal cell carcinoma, Kaposi's Sarcoma, melanoma, virus and fungal infections. We concluded that used together with a recently developed continuous light source (RL50(®)), MB has the potential to treat a variety of cancerous and non-cancerous diseases, with low toxicity and no side effects.