Catalytic Nanoparticles in Biomedical Applications: Exploiting Advanced Nanozymes for Therapeutics and Diagnostics

Catalytic nanoparticles (CNPs) as heterogeneous catalyst reveals superior activity due to their physio-chemical features, such as high surface-to-volume ratio and unique optical, electric, and magnetic properties. The CNPs, based on their physio-chemical nature, can either increase the reactive oxygen species (ROS) level for tumor and antibacterial therapy or eliminate the ROS for cytoprotection, anti-inflammation, and anti-aging. In addition, the catalytic activity of nanozymes can specifically trigger a specific reaction accompanied by the optical feature change, presenting the feasibility of biosensor and bioimaging applications. Undoubtedly, CNPs play a pivotal role in pushing the evolution of technologies in medical and clinical fields, and advanced strategies and nanomaterials rely on the input of chemical experts to develop. Herein, a systematic and comprehensive review of the challenges and recent development of CNPs for biomedical applications is presented from the viewpoint of advanced nanomaterial with unique catalytic activity and additional functions. Furthermore, the biosafety issue of applying biodegradable and non-biodegradable nanozymes and future perspectives are critically discussed to guide a promising direction in developing span-new nanozymes and more intelligent strategies for overcoming the current clinical limitations.

The degradation of single-use plastics and commercially viable bioplastics in the environment: A review

Plastics have become an integral part of human life. Single-use plastics (SUPs) are disposable plastics designed to be used once then promptly discarded or recycled. This SUPs range from packaging and takeaway containers to disposable razors and hotel toiletries. Synthetic plastics, which are made of non-renewable petroleum and natural gas resources, require decades to perpetually disintegrate in nature thus contribute to plastic pollution worldwide, especially in marine environments. In response to these problems, bioplastics or bio-based and biodegradable polymers from renewable sources has been considered as an alternative. Understanding the mechanisms behind the degradation of conventional SUPs and biodegradability of their greener counterpart, bioplastics, is crucial for appropriate material selection in the future. This review aims to provide insights into the degradation or disintegration of conventional single-use plastics and the biodegradability of the different types of greener-counterparts, bioplastics, their mechanisms, and conditions. This review highlights on the biodegradation in the environments including composting systems. Here, the various types of alternative biodegradable polymers, such as bacterially biosynthesised bioplastics, natural fibre-reinforced plastics, starch-, cellulose-, lignin-, and soy-based polymers were explored. Review of past literature revealed that although bioplastics are relatively eco-friendly, their natural compositions and properties are inconsistent. Furthermore, the global plastic market for biodegradable plastics remains relatively small and require further research and commercialization efforts, especially considering the urgency of plastic and microplastic pollution as currently critical global issue. Biodegradable plastics have potential to replace conventional plastics as they show biodegradation ability under real environments, and thus intensive research on the various biodegradable plastics is needed to inform stakeholders and policy makers on the appropriate response to the gradually emerging biodegradable plastics.

Recent progress and future directions of membranes green polymers for oily wastewater treatment

The preparation, modification and application of green polymers such as poly-lactic acid (PLA), chitosan (CS), and cellulose acetate (CA) for oily wastewater treatment is summed up in this review. Due to the low environmental pollution, good chemical resistivity, high hydrophobicity, and good capacity for water-oil emulsion separation of the presented polymers, it then highlights the various membrane production methods and their role in producing effective membranes, with a focus on recent advances in improving membrane properties through the addition of various Nano materials. As a result, the hydrophilic/hydrophobic properties that are critical in the oil separation mechanism are highlighted. Finally, it looks at the predictions and challenges in oil/water separation and recovery. These ideas are discussed with a focus on modern production methods and oil separation proficiency.

Riboflavin as a Biodegradable Functional Additive for Thermoplastic Polymers

With continuous development of biodegradable polymers, new areas of applications are intensively researched. Modifications of these polymers are commonly conducted by an extrusion compounding process. While additives are changing desired properties, biodegradability of such composites can be deteriorated. The aim of the work is to investigate a novel, functional, organic additive, riboflavin (vitamin B-2), in terms of thermal stability, extrusion processability, wettability, surface energy, especially biodegradability, and when compounded with PLA. Additionally, a comparison of unmodified PLA resin, as well as PLA-modified with inorganic talc—which is known for its nucleation promotion in a variety of polymers—to PLA with riboflavin, was presented. Research reveals the outstanding thermal stability of riboflavin and the sufficient extrusion process properties with no significant changes of wettability and, surprisingly, a significant degradation rate as compared to pure PLA or and PLA with talc. The obtained results do not exclude further modifications of PLA depending on the target application, e.g., antimicrobial agents, flame retardants, etc.

Potential of Serratia plymuthica IV-11-34 strain for biodegradation of polylactide and poly(ethylene terephthalate)

Serratia plymuthica strain IV-11-34 belongs to the plant growth promoting bacteria (PGPR). In the sequenced genome of S. plymuthica IV-11-34, we have identified the genes involved in biodegradation and metabolisms of xenobiotics. The potential of S. plymuthica IV-11-34 for the degradation of biodegradable aliphatic polyester polylactide (PLA) and resistant to biodegradation - poly(ethylene terephthalate) (PET) was assessed by biochemical oxygen consumption (BOD) and carbon dioxide methods. After seven days of growth, the bacteria strain showed more than 80% and 60% increase in respiratory activity in the presence of PLA and PET, respectively. We assume that during biodegradation, S. plymuthica IV-11-34 colonise the surface of PLA and PET, since the formation of a biofilm on the surface of polymers was shown by the LIVE/DEAD method. We have demonstrated for the relA gene, which is an alarmone synthetase, a 1.2-fold increase in expression in the presence of PLA, and a 4-fold decrease in expression in the presence of PET for the spoT gene, which is a hydrolase of alarmones. Research has shown that the bacterium has the ability to biodegrade PLA and PET, and the first stage of this process involves bacterial stringent response genes responsible for survival under extreme conditions.

Starch-based isocyanate- and non-isocyanate polyurethane hybrids: A review on synthesis, performance and biodegradation

The challenges related to the persistence of plastics in natural ecosystems fostered strong interest in developing biodegradable bioplastics. Among natural biopolymers, starch gained both academic and industrial interest owing to its impressive physicochemical properties. The use of starch in production of polyurethane (PU) composites not only yields PUs with outstanding mechanical properties but also makes the final PU products biodegradable. The hydrophilic nature of starch limits its dispersion in hydrophobic PU polymers, although it is a significant benefit in creating starch-embedded non-isocyanate polyurethane (NIPU) composites. We present a comprehensive overview to highlight important strategies that are used to improve the compatibility of starch with various PU matrices. This review also gives an overview of the recent advances in the synthesis of starch-NIPU hybrids. Moreover, we aim to deliver critical insight into strategies that boost the biodegradation characteristics of PUs along with a discussion on various methods to assess their biodegradation.

Poly Lactic Acid (PLA) Nanocomposites: Effect of Inorganic Nanoparticles Reinforcement on Its Performance and Food Packaging Applications

Poly lactic acid (PLA) is a compostable, as well as recyclable, sustainable, versatile and environmentally friendly alternative, because the monomer of PLA-lactide (LA) is extracted from natural sources. PLA’s techno-functional properties are fairly similar to fossil-based polymers; however, in pristine state, its brittleness and delicacy during processing pose challenges to its potential exploitation in diverse food packaging applications. PLA is, therefore, re-engineered to improve its thermal, rheological, barrier and mechanical properties through nanoparticle (NP) reinforcement. This review summarises the studies on PLA-based nanocomposites (PLA NCs) developed by reinforcing inorganic metal/metallic oxide, graphite and silica-based nanoparticles (NPs) that exhibit remarkable improvement in terms of storage modulus, tensile strength, crystallinity, glass transition temperature (Tg) value, antimicrobial property and a decrease in water vapour and oxygen permeability when compared with the pristine PLA films. This review has also discussed the regulations around the use of metal oxide-based NPs in food packaging, PLA NC biodegradability and their applications in food systems. The industrial acceptance of NCs shows highly promising perspectives for the replacement of traditional petrochemical-based polymers currently being used for food packaging.

Combined use of Bacillus strains and Miscanthus for accelerating biodegradation of poly(lactic acid) and poly(ethylene terephthalate)

Background

The aim of this study was to verify whether the presence of Bacillus strains and of miscanthus influence biodegradation and formed of biofilm of poly(lactic acid) (PLA) and poly(ethylene terephthalate) (PET).

Methods

The experiment conducted in compost soil showed that strains Bacillus subtilis and Bacillus cereus isolated from heavy metal contaminated environment have biochemical activity and accelerate biodegradation of both plastic materials.

Results

For PLA film it was found that the carbonyl index dropped by over 15% in the presence of B. subtilis, while the film tensile strength decreased by 35% and the oxygen to carbon O/C ratio was higher by 3% in the presence of B. cereus, and the presence of miscanthus resulted in a loss of weight. For PET film, a decrease in the carbonyl index by 16% was observed following inoculation with B. cereus. The metabolic activity of this strain contributed to the reduction of the film’s tensile strength by 17% and to the increase in the permeability to O₂ and CO₂. The most intense degradation of PET film was observed in the presence of bacteria and plants. B. subtilis strain combined with miscanthus plantings may be a promising method for accelerating PLA and PET degradation in compost soil.

Biodegradation of Hemicellulose-Cellulose-Starch-Based Bioplastics and Microbial Polyesters

The volume of discarded solid wastes, especially plastic, which accumulates in large quantities in different environments, has substantially increased. Population growth and the consumption pattern of societies associated with unsustainable production routes have caused the pollution level to increase. Therefore, the development of materials that help mitigate the impacts of plastics is fundamental. However, bioplastics can result in a misunderstanding about their properties and environmental impacts, as well as incorrect management of their final disposition, from misidentifications and classifications. This chapter addresses the aspects and factors surrounding the biodegradation of bioplastics from natural (plant biomass (starch, lignin, cellulose, hemicellulose, and starch) and bacterial polyester polymers. Therefore, the biodegradation of bioplastics is a factor that must be studied, because due to the increase in the production of different bioplastics, they may present differences in the decomposition rates.

Mass spectrometry in bioresorbable polymer development, degradation and drug-release tracking

A detailed characterization of polymeric matrices and appropriate degradation monitoring techniques are required to sustain the development of new materials as well as to enlarge the applications of the old ones. In fact, polymer analysis is essential for the clarification of the intrinsic relationship between structure and properties that ascertains the industrial applications in diverse fields. In bioresorbable and biodegradable polymers, the role of analytical methods is dual since it is pointed both at the polymeric matrices and at degradation tracking. The structural architectures, the mechanical and morphological properties, and the degradation rate, are of outstanding importance for a specific application. In some cases, the complexity of the polymer structure, the processes of decomposition or the low concentration of the degradation products need the concurrent use of different complementary analytical techniques to give detailed information of the reactions taking place. Several analytical methods are used in bioresorbable polymer development and degradation tracking. Among them, mass spectrometry (MS) plays an essential role and it is used to refine polymer syntheses, for its high sensitivity, to highlight degradation mechanism by detecting compounds present in trace amounts, or to track the degradation product profile and to study drug release. In fact, elucidation of reaction mechanisms and polymer structure, attesting to the purity and detecting defects as well as residual catalysts, in biodegradable and bioresorbable polymers, requires sensitive analytical characterization methods that are essential in providing an assurance of safety, efficacy and quality. This review aims to provide an overview of the MS strategies used to support research and development of resorbable polymers as well as to investigate their degradation mechanisms. It is focused on the most significant studies concerning synthetic bioresorbable matrices (polylactide, polyglycolide and their copolymers, polyhydroxybutyrate, etc.), published in the last ten years.

Effects of Nanofillers on the Hydrolytic Degradation of Polyesters

Biopolymer matrices reinforced with nanoparticles or nanofillers have received a great deal of attention over the past decades due to their various roles such as the augmentation of thermal, electrical, mechanical, and surface properties in tissue engineering, drug delivery, and implantation. Understanding the degradation kinetics of these polyesters is very important to successful applications of them. Hydrolysis is a widely agreed mechanism for the polyester degradation. According to this mechanism, hydrolytic degradation of these polyesters can be affected by the autocatalytic action of carboxyl groups as well as other factors such as hydrophilicity, crystallinity, and glass transition temperature. In this article, the effects of nanofillers on the autocatalytic action of carboxyl groups and the foregoing factors are examined. A particular attention is paid to carbon nanotubes (CNTs), which are a favorite candidate in a wide range of applications due to their unique thermal and electrical properties. Contradictory degradation results with CNTs are reported and analyzed. Finally, a future research perspective on these polyesters is discussed. Impact statement Nanoparticles have attracted a great deal of attention over the past decades due to their various roles, such as the augmentation of thermal, electrical, mechanical, and surface properties in tissue engineering, drug delivery, and implantation. In this article, the effects of nanoparticles or nanofillers* on the degradation behavior of the polyester matrices (tissue scaffolds, drug delivery devices) are examined with a focus on the autocatalytic action of carboxyl groups, and the factors such as hydrophilicity, crystallinity, and glass transition temperature. Among many nanofillers, carbon nanotubes (CNTs), which are a favorite candidate in a wide range of applications, are found to produce some contradictory results on the degradation of the polyester matrix with CNTs incorporated, and the underlying reason for this finding is discussed for the first time in this article.

Polymeric nanoparticles as carrier for targeted and controlled delivery of anticancer agents

In recent decades, many novel methods by using nanoparticles (NPs) have been investigated for diagnosis, drug delivery and treatment of cancer. Accordingly, the potential of NPs as carriers is very significant for the delivery of anticancer drugs, because cancer treatment with NPs has led to the improvement of some of the drug delivery limitations such as low blood circulation time and bioavailability, lack of water solubility, drug adverse effect. In addition, the NPs protect drugs against enzymatic degradation and can lead to the targeted and/or controlled release of the drug. The present review focuses on the potential of NPs that can help the targeted and/or controlled delivery of anticancer agents for cancer therapy.

Structure and Dynamics of Biobased Polyester Nanocomposites

The structure and the dynamics of two bio-based polyester polyols are investigated in the bulk and close to surfaces in polymer/layered silicate nanocomposites. The morphology of the neat polymers as well as the structure of the nanohybrids are investigated with X-ray diffraction and their thermal properties are studied by differential scanning calorimetry. One of the investigated polyesters is amorphous, whereas the second one is a semicrystalline polymer with intriguing thermal behavior. Hybrids have been synthesized over a broad range of compositions and intercalated structures are always obtained. The thermal transitions in the nanocomposites are observed only when the polymers are in excess outside the completely filled galleries. The glass transition, whenever it can be resolved, appears insensitive to the presence of the inorganic material, whereas the way the crystallization takes place depends on the composition of the nanohybrid. Dielectric relaxation spectroscopy was utilized to study the polymer dynamics. It revealed multiple relaxation processes for the neat polymers both below and above their glass transition temperatures, whereas in the nanocomposites, similarities and differences are observed depending on the specific mode of the dynamic process.

Recent Advances in Nanocomposites Based on Aliphatic Polyesters: Design, Synthesis, and Applications in Regenerative Medicine

In the last decade, biopolymer matrices reinforced with nanofillers have attracted great research efforts thanks to the synergistic characteristics derived from the combination of these two components. In this framework, this review focuses on the fundamental principles and recent progress in the field of aliphatic polyester-based nanocomposites for regenerative medicine applications. Traditional and emerging polymer nanocomposites are described in terms of polymer matrix properties and synthesis methods, used nanofillers, and nanocomposite processing and properties. Special attention has been paid to the most recent nanocomposite systems developed by combining alternative copolymerization strategies with specific nanoparticles. Thermal, electrical, biodegradation, and surface properties have been illustrated and correlated with the nanoparticle kind, content, and shape. Finally, cell-polymer (nanocomposite) interactions have been described by reviewing analysis methodologies such as primary and stem cell viability, adhesion, morphology, and differentiation processes.

Biodegradation of Carbon Nanotube/Polymer Nanocomposites using a Monoculture

The biodegradation rates of carbon nanotube (CNT)/ polymer nanocomposites (PNCs) containing poly-ε-caprolactone (PCL) were investigated using Pseudomonas aeruginosa, a microorganism commonly found in the environment. CNT/PCL nanocomposite mass loss profiles revealed that the rate of PCL matrix biodegradation decreased systematically as the CNT loading increased from 0.1 to 10% w/w. Addition of even a low CNT loading (<1% w/w) caused the CNT/PCL biodegradation rate constant to decrease by more than 50%. Similar trends in biodegradation rate were observed for both pristine and oxidized multiwall CNTs embedded in PCL. During PCL matrix biodegradation, CNT accumulation was observed at the surface of CNT/PCL nanocomposites and single particle inductively coupled-mass spectrometry experiments revealed no measurable CNT release to the culture fluid. Experimental data indicated that biodegradation proceeded as a result of biofilm formation on the CNT/PCL nanocomposites and decreased as a function of CNT loading due to the cytotoxicity of CNTs toward P. aeruginosa and the physical barrier presented by the surface-accumulated CNTs to the underlying PCL substrate. As the CNT loading in the CNT/PCL nanocomposites increased, the microbial proliferation of planktonic cells in the surrounding media also decreased as did the biodegradation rate of PCL samples present in the same reactors. Results from this study demonstrate that the inclusion of CNTs into polymer matrices could increase the environmental persistence of polymers in lakes, landfills, and surface waters.

Effects of polymers on the properties of hydrogels constructed using sodium deoxycholate and amino acid

Polymer can participate in the formation of hydrogel network structure and provide a lot of binding sites, leading to an enhancement of the mechanical strength of the hydrogels.

Amphiphilic polypeptides with prolonged enzymatic stability for the preparation of self-assembled nanobiomaterials

Aib residue distribution in Lys/Aib polymers influences the morphology of forming nanoparticles and the rate of their enzymatic degradation.

Unraveling the molecular mechanism of photosynthetic toxicity of highly fluorescent silver nanoclusters to Scenedesmus obliquus

While the discovery of numerous attractive properties of silver at the nanoscale has increased their demand in many sectors including medicine, optics, sensing, painting and cosmetics, it has also raised wide public concerns about their effect on living organisms in aquatic environment. Despite the continuous effort to understand the various aspects of the toxicity of silver nanomaterials, the molecular level understanding on their cytotoxicity mechanism to biological organisms has remained unclear. Herein, we demonstrated the underlying mechanism of the photosynthetic toxicity against green algae namely, Scenedesmus obliquus by using an emerging silver nanomaterial, called silver nanoclusters (defined as r-Ag NCs). By exploiting the unique fluorescence properties of r-Ag NCs along with various other analytical/biological tools, we proposed that the photosynthetic toxicity of r-Ag NCs was largely attributed to the "joint-toxicity" effect of particulate form of r-Ag NCs and its released Ag+, which resulted in the disruption of the electron transport chain of light reaction and affected the content of key enzymes (RuBP carboxylase/ oxygenase) of Calvin cycle of algae cells. We believe that the present study can also be applied to the assessment of the ecological risk derived from other metal nanoparticles.

Polymer-lipid-PEG hybrid nanoparticles as photosensitizer carrier for photodynamic therapy

Polymer-lipid-PEG hybrid nanoparticles were investigated as carriers for the photosensitizer (PS), 5,10,15,20-Tetrakis(4-hydroxy-phenyl)-21H,23H-porphine (pTHPP) for use in photodynamic therapy (PDT). A self-assembled nanoprecipitation technique was used for preparing two types of core polymers poly(d,l-lactide-co-glycolide) (PLGA) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) with lipid-PEG as stabilizer. The resulting nanoparticles had an average particle size of 88.5±3.4nm for PLGA and 215.0±6.3nm for PHBV. Both nanoparticles exhibited a core-shell structure under TEM with high zeta potential and loading efficiency. X-ray powder diffraction analysis showed that the encapsulated pTHPP molecules in polymeric nanoparticles no longer had peaks of free pTHPP in the crystalline state. The pTHPP molecules encapsulated inside the polymeric core demonstrated improved photophysical properties in terms of singlet oxygen generation and cellular uptake rate in a FTC-133 human thyroid carcinoma cell line, compared to non-encapsulated pTHPP. The pTHPP-loaded polymer-lipid-PEG nanoparticles showed better in vitro phototoxicity compared to free pTHPP, in both time- and concentration-dependent manners. Overall, this study provides detailed analysis of the photophysical properties of pTHPP molecules when entrapped within either PLGA or PHBV nanoparticle cores, and demonstrates the effectiveness of these systems for delivery of photosensitizers. The two polymeric systems may have different potential benefits, when used with cancer cells. For instance, the pTHPP-loaded PLGA system requires only a short time to show a PDT effect and may be suitable for topical PDT, while the delayed photo-induced cytotoxic effect of the pTHPP-loaded PHBV system may be more suitable for cancer solid tumors. Hence, both pTHPP-encapsulated polymer-lipid-PEG nanoparticles can be considered promising delivery systems for PDT cancer treatment.

Surface spermidine functionalized PEGylated poly(lactide-co-glycolide) nanoparticles for tumor-targeted drug delivery

SPD functionalized nanoparticles could target the delivery of a drug into tumor cells by binding specifically with PTS.

Multiphase TiO2nanostructures: a review of efficient synthesis, growth mechanism, probing capabilities, and applications in bio-safety and health

This review article provides an exhaustive overview of efficient synthesis, growth mechanism and research activities of multiphase TiO₂nanostructures to provide their structural, morphological, optical and biological properties co-relations.