Combining analytical techniques to assess the translocation of diesel particles across an alveolar tissue barrier in vitro.

BACKGROUND: During inhalation, airborne particles such as particulate matter ≤ 2.5 µm (PM2.5), can deposit and accumulate on the alveolar epithelial tissue. In vivo studies have shown that fractions of PM2.5 can cross the alveolar epithelium to blood circulation, reaching secondary organs beyond the lungs. However, approaches to quantify the translocation of particles across the alveolar epithelium in vivo and in vitro are still not well established. In this study, methods to assess the translocation of standard diesel exhaust particles (DEPs) across permeable polyethylene terephthalate (PET) inserts at 0.4, 1, and 3 µm pore sizes were first optimized with transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-VIS), and lock-in thermography (LIT), which were then applied to study the translocation of DEPs across human alveolar epithelial type II (A549) cells. A549 cells that grew on the membrane (pore size: 3 µm) in inserts were exposed to DEPs at different concentrations from 0 to 80 µg.mL- 1 ( 0 to 44 µg.cm- 2) for 24 h. After exposure, the basal fraction was collected and then analyzed by combining qualitative (TEM) and quantitative (UV-VIS and LIT) techniques to assess the translocated fraction of the DEPs across the alveolar epithelium in vitro. RESULTS: We could detect the translocated fraction of DEPs across the PET membranes with 3 µm pore sizes and without cells by TEM analysis, and determine the percentage of translocation at approximatively 37% by UV-VIS (LOD: 1.92 µg.mL- 1) and 75% by LIT (LOD: 0.20 µg.cm- 2). In the presence of cells, the percentage of DEPs translocation across the alveolar tissue was determined around 1% at 20 and 40 µg.mL- 1 (11 and 22 µg.cm- 2), and no particles were detected at higher and lower concentrations. Interestingly, simultaneous exposure of A549 cells to DEPs and EDTA can increase the translocation of DEPs in the basal fraction. CONCLUSION: We propose a combination of analytical techniques to assess the translocation of DEPs across lung tissues. Our results reveal a low percentage of translocation of DEPs across alveolar epithelial tissue in vitro and they correspond to in vivo findings. The combination approach can be applied to any traffic-generated particles, thus enabling us to understand their involvement in public health.

Improving plastic degrading enzymes via directed evolution.

Plastic degrading enzymes have immense potential for use in industrial applications. Protein engineering efforts over the last decade have resulted in considerable enhancement of many properties of these enzymes. Directed evolution, a protein engineering approach that mimics the natural process of evolution in a laboratory, has been particularly useful in overcoming some of the challenges of structure-based protein engineering. For example, directed evolution has been used to improve the catalytic activity and thermostability of polyethylene terephthalate (PET)-degrading enzymes, although its use for the improvement of other desirable properties, such as solvent tolerance, has been less studied. In this review, we aim to identify some of the knowledge gaps and current challenges, and highlight recent studies related to the directed evolution of plastic-degrading enzymes.

Microplastics and non-natural cellulosic particles in Spanish bottled drinking water.

This investigation explored the presence of microplastics (MPs) and artificial cellulosic particles (ACPs) in commercial water marketed in single use 1.5 L poly(ethylene terephthalate) bottles. In this work we determined a mass concentration of 1.61 (1.10-2.88) µg/L and 1.04 (0.43-1.82) µg/L for MPs and ACPs respectively in five top-selling brands from the Spanish bottled water market. Most MPs consisted of white and transparent polyester and polyethylene particles, while most ACPs were cellulosic fibers likely originating from textiles. The median size of MPs and ACPs was 93 µm (interquartile range 76-130 µm) and 77 µm (interquartile range 60-96 µm), respectively. Particle mass size distributions were fitted to a logistic function, enabling comparisons with other studies. The estimated daily intake of MPs due to the consumption of bottled water falls within the 4-18 ng kg-1 day-1 range, meaning that exposure to plastics through bottled water probably represents a negligible risk to human health. However, it's worth noting that the concentration of plastic found was much higher than that recorded for tap water, which supports the argument in favour of municipal drinking water.

Understanding the stability of a plastic-degrading Rieske iron oxidoreductase system.

Rieske oxygenases (ROs) are a diverse metalloenzyme class with growing potential in bioconversion and synthetic applications. We postulated that ROs are nonetheless underutilized because they are unstable. Terephthalate dioxygenase (TPADO PDB ID 7Q05) is a structurally characterized heterohexameric α3ß3 RO that, with its cognate reductase (TPARED), catalyzes the first intracellular step of bacterial polyethylene terephthalate plastic bioconversion. Here, we showed that the heterologously expressed TPADO/TPARED system exhibits only ~300 total turnovers at its optimal pH and temperature. We investigated the thermal stability of the system and the unfolding pathway of TPADO through a combination of biochemical and biophysical approaches. The system's activity is thermally limited by a melting temperature (Tm) of 39.9°C for the monomeric TPARED, while the independent Tm of TPADO is 50.8°C. Differential scanning calorimetry revealed a two-step thermal decomposition pathway for TPADO with Tm values of 47.6 and 58.0°C (ΔH = 210 and 509 kcal mol-1, respectively) for each step. Temperature-dependent small-angle x-ray scattering and dynamic light scattering both detected heat-induced dissociation of TPADO subunits at 53.8°C, followed by higher-temperature loss of tertiary structure that coincided with protein aggregation. The computed enthalpies of dissociation for the monomer interfaces were most congruent with a decomposition pathway initiated by ß-ß interface dissociation, a pattern predicted to be widespread in ROs. As a strategy for enhancing TPADO stability, we propose prioritizing the re-engineering of the ß subunit interfaces, with subsequent targeted improvements of the subunits.

Probing Enzymatic PET Degradation: Molecular Dynamics Analysis of Cutinase Adsorption and Stability.

Understanding the mechanisms influencing poly(ethylene terephthalate) (PET) biodegradation is crucial for developing innovative strategies to accelerate the breakdown of this persistent plastic. In this study, we employed all-atom molecular dynamics simulation to investigate the adsorption process of the LCC-ICCG cutinase enzyme onto the PET surface. Our results revealed that hydrophobic, π-π, and H bond interactions, specifically involving aliphatic, aromatic, and polar uncharged amino acids, were the primary driving forces for the adsorption of the cutinase enzyme onto PET. Additionally, we observed a negligible change in the enzyme's tertiary structure during the interaction with PET (RMSD = 1.35 Å), while its secondary structures remained remarkably stable. Quantitative analysis further demonstrated that there is about a 24% decrease in the number of enzyme-water hydrogen bonds upon adsorption onto the PET surface. The significance of this study lies in unraveling the molecular intricacies of the adsorption process, providing valuable insights into the initial steps of enzymatic PET degradation.

Discovery and characterization of two novel polyethylene terephthalate hydrolases: One from a bacterium identified in human feces and one from the Streptomyces genus.

Polyethylene terephthalate (PET) is widely used for various industrial applications. However, owing to its extremely slow breakdown rate, PET accumulates as plastic trash, which negatively affects the environment and human health. Here, we report two novel PET hydrolases: PpPETase from Pseudomonas paralcaligenes MRCP1333, identified in human feces, and ScPETase from Streptomyces calvus DSM 41452. These two enzymes can decompose various PET materials, including semicrystalline PET powders (Cry-PET) and low-crystallinity PET films (gf-PET). By structure-guided engineering, two variants, PpPETaseY239R/F244G/Y250G and ScPETaseA212C/T249C/N195H/N243K were obtained that decompose Cry-PET 3.1- and 1.9-fold faster than their wild-type enzymes, respectively. The co-expression of ScPETase and mono-(2-hydroxyethyl) terephthalate hydrolase from Ideonella sakaiensis (IsMHETase) resulted in 1.4-fold more degradation than the single enzyme system. This engineered strain degraded Cry-PET and gf-PET by more than 40% and 6%, respectively, after 30 d. The concentrations of terephthalic acid (TPA) in the Cry-PET and gf-PET degradation products were 37.7% and 25.6%, respectively. The discovery of these two novel PET hydrolases provides opportunities to create more powerful biocatalysts for PET biodegradation.

Characterization of Thermotoga maritima Esterase Capable of Hydrolyzing Bis(2-hydroxyethyl) Terephthalate.

The gene-encoding carboxylesterase (TM1022) from the hyperthermophilic bacterium Thermotoga maritima (T. maritima) was cloned and expressed in Escherichia coli Top10 and BL21 (DE3). Recombinant TM1022 showed the best activity at pH 8.0 and 85 °C and retained 57% activity after 8 h cultivation at 90 °C. TM1022 exhibited good stability at pH 6.0-9.0, maintaining 53% activity after incubation at pH 10.0 and 37 °C for 6 h. The esterase TM1022 exhibited the optimum thermo-alkali stability and kcat/Km (598.57 ± 19.97 s-1mM-1) for pN-C4. TM1022 hydrolyzed poly(ethylene terephthalate) (PET) degradation intermediates, such as bis(2-hydroxyethyl) terephthalate (BHET) and mono(2-hydroxyethyl) terephthalate (MHET). The Km, kcat, and kcat/Km values for BHET were 0.82 ± 0.01 mM, 2.20 ± 0.02 s-1, and 2.67 ± 0.02 mM-1 s-1, respectively; those for MHET were 2.43 ± 0.07 mM, 0.04 ± 0.001 s-1, and 0.02 ± 0.001 mM-1 s-1, respectively. When purified TM1022 was added to the cutinase BhrPETase, hydrolysis of PET from drinking water bottle tops produced pure terephthalic acids (TPA) with 166% higher yield than those obtained after 72 h of incubation with BhrPETase alone as control. The above findings demonstrate that the esterase TM1022 from T. maritima has substantial potential for depolymerizing PET into monomers for reuse.

Development and characterization of a bacterial enzyme cascade reaction system for efficient and stable PET degradation.

The widespread use of polyethylene terephthalate (PET) in various industries has led to a surge in microplastics (MPs) pollution, posing a significant threat to ecosystems and human health. To address this, we have developed a bacterial enzyme cascade reaction system (BECRS) that focuses on the efficient degradation of PET. This system harnesses the Escherichia coli (E. coli) surface to display CsgA protein, which forms curli fibers, along with the carbohydrate-binding module 3 (CBM3) and PETases, to enhance the adsorption and degradation of PET. The study demonstrated that the BECRS achieved a notable PET film degradation rate of 3437 ± 148 µg/(d*cm²), with a degradation efficiency of 21.40% for crystalline PET MPs, and the degradation products were all converted to TPA. The stability of the system was evidenced by retaining over 80% of its original activity after multiple uses and during one month of storage. Molecular dynamics simulations confirmed that the presence of CsgA did not interfere with the enzymatic activity of PETases. This BECRS represents a significant step forward in the biodegradation of PET, particularly microplastics, offering a practical and sustainable solution for environmental pollution control.

Ovalbumin interaction with polystyrene and polyethylene terephthalate microplastics alters its structural properties.

Contaminating microplastics can interact with food proteins in the food matrix and during digestion. This study investigated adsorption of chicken egg protein ovalbumin to polystyrene (PS, 110 and 260 µm) and polyethylene terephthalate (PET, 140 µm) MPs in acidic and neutral conditions and alterations in ovalbumin structure. Ovalbumin adsorption affinity depended on MPs size (smaller > larger), type (PS > PET) and pH (pH 3 > pH 7). In bulk solution, MPs does not change ovalbumin secondary structure significantly, but induces loosening (at pH 3) and tightening (at pH 7) of tertiary structure. Formed soft corona exclusively consists of full length non-native ovalbumin, while in hard corona also shorter ovalbumin fragments were found. At pH 7 soft corona ovalbumin has rearranged but still preserved level of ordered secondary structure, resulting in preserved thermostability and proteolytic stability, but decreased ability to form fibrils upon heating. Secondary structure changes in soft corona resemble changes in native ovalbumin induced by heat treatment (80 °C). Ovalbumin is abundantly present in corona around microplastics also in the presence of other egg white proteins. These results imply that microplastics contaminating food may bind and change structure and functional properties of the main egg white protein.

Persistence of A-234 nerve agent on indoor surfaces.

Understanding the fundamental physical characteristics of extremely toxic compounds and their behavior across different environments plays a crucial role in assessing their danger. Additionally, this knowledge informs the development of protocols for gathering forensic evidence related to harmful chemicals misuse. In 2018, former Russian spy Sergei Skripal and his daughter were poisoned in Salisbury, England, with a substance later identified as the unconventional nerve agent A-234. Contamination with the compound was found on items inside Skripal's home. The aim of this paper was to determine the persistence of A-234 on selected indoor surfaces. Ceramics, aluminum can, laminated chipboard, polyvinyl chloride (PVC) floor tile, polyethylene terephthalate (PET) bottle, acrylic paint and computer keyboard were used as matrices. The decrease in surface contamination and further fate of the compound was monitored for 12 weeks. Persistence determination involved optimizing the wipe sampling method. Simultaneously, evaporation from the surface and permeation of the contaminant into the matrix were closely monitored. The experimental findings indicate that the nerve agent exhibits remarkable persistence, particularly on impermeable surfaces. Notably, the process of A-234 evaporation plays a minor role in determining its fate, with detectable concentrations observed solely above solid, non-porous surfaces such as ceramics and aluminum can. The surface persistence half-life varied significantly, ranging from 12 min to 478 days, depending on the material. The article has implications for emergency response protocols, decontamination strategies, public health and crime scene investigations.

Enhancing PET Degrading Enzymes: A Combinatory Approach.

Plastic waste has become a substantial environmental issue. A potential strategy to mitigate this problem is to use enzymatic hydrolysis of plastics to depolymerize post-consumer waste and allow it to be reused. Over the last few decades, the use of enzymatic PET-degrading enzymes has shown promise as a great solution for creating a circular plastic waste economy. PsPETase from Piscinibacter sakaiensis has been identified as an enzyme with tremendous potential for such applications. But to improve its efficiency, enzyme engineering has been applied aiming at enhancing its thermal stability, enzymatic activity, and ease of production. Here, we combine different strategies such as structure-based rational design, ancestral sequence reconstruction and machine learning to engineer a more highly active Combi-PETase variant with a melting temperature of 70 °C and optimal performance at 60 °C. Furthermore, this study demonstrates that these approaches, commonly used in other works of enzyme engineering, are most effective when utilized in combination, enabling the improvement of enzymes for industrial applications.

Characterization and elimination efficiency of volatile organic compounds in mechanically recycled polyethylene terephthalate at various recycling stages.

The recycling of polyethylene terephthalate (PET) stands as an effective strategy for mitigating plastic pollution and reducing resource waste. The study aimed to investigate the characterization and elimination efficiency of volatile organic compounds (VOCs) present in rPET at various recycling stages using comprehensive two-dimensional gas chromatography-quadrupole-time-of-flight-mass spectrometry coupled with chemometrics. The results revealed that 52, 135, 95, 44, and 33 VOCs, mostly classified into three chemical groups, were tentatively identified in virgin - PET (v-PET), cold water washed - rPET (C-rPET), decontaminated - rPET (D-rPET), melt-extruded - rPET (M-rPET), and solid-state polycondensation - rPET (S-rPET), respectively. Regarding the VOCs with high and median detection frequencies, fatty acyls showed the highest elimination efficiency (100 % and 92 %), followed by organooxygen compounds (81 % and 99 %), others (97 % and 95 %), and benzene and substituted derivatives (82 % and 95 %) in term of HS-SPME. Following the recycling process, there was a general decrease in the concentration of almost all VOCs, as evidenced by the substantial reduction of o-Xylene, hexanoic acid, octanal, and D-limonene from 18.11, 22.43, 30.74, and 7.41 mg/kg to 0, 0, 3.97, and 0 mg/kg, respectively. However, it was noteworthy that the VOCs identified in the samples were not completely extracted, owing to the limitations of HS-SPME. Furthermore, chemometrics analysis indicated significant discrimination among VOCs from vPET, C-rPET, D-rPET, and M-rPET, while indistinct differences were observed between M-rPET and S-rPET. This study contributes to the enhancement of the recycling process and emphasizes the importance of safeguarding consumer health in terms of elimination of VOCs.

Exploring the substrate spectrum of phylogenetically distinct bacterial polyesterases.

The rapid escalation of plastic waste accumulation presents a significant threat of the modern world, demanding an immediate solution. Over the last years, utilization of the enzymatic machinery of various microorganisms has emerged as an environmentally friendly asset in tackling this pressing global challenge. Thus, various hydrolases have been demonstrated to effectively degrade polyesters. Plastic waste streams often consist of a variety of different polyesters, as impurities, mainly due to wrong disposal practices, rendering recycling process challenging. The elucidation of the selective degradation of polyesters by hydrolases could offer a proper solution to this problem, enhancing the recyclability performance. Towards this, our study focused on the investigation of four bacterial polyesterases, including DaPUase, IsPETase, PfPHOase, and Se1JFR, a novel PETase-like lipase. The enzymes, which were biochemically characterized and structurally analyzed, demonstrated degradation ability of synthetic plastics. While a consistent pattern of polyesters' degradation was observed across all enzymes, Se1JFR stood out in the degradation of PBS, PLA, and polyether PU. Additionally, it exhibited comparable results to IsPETase, a benchmark mesophilic PETase, in the degradation of PCL and semi-crystalline PET. Our results point out the wide substrate spectrum of bacterial hydrolases and underscore the significant potential of PETase-like enzymes in polyesters degradation.

Smart Graphene Textiles for Biopotential Monitoring: Laser-Tailored Electrochemical Property Enhancement.

While most of the research in graphene-based materials seeks high electroactive surface area and ion intercalation, here, we show an alternative electrochemical behavior that leverages graphene's potential in biosensing. We report a novel approach to fabricate graphene/polymer nanocomposites with near-record conductivity levels of 45 Ω sq-1 and enhanced biocompatibility. This is realized by laser processing of graphene oxide in a sandwich structure with a thin (100 µm) polyethylene terephthalate film on a textile substrate. Such hybrid materials exhibit high conductivity, low polarization, and stability. In addition, the nanocomposites are highly biocompatible, as evidenced by their low cytotoxicity and good skin adhesion. These results demonstrate the potential of graphene/polymer nanocomposites for smart clothing applications.

Molecular Insights into the Enhanced Activity and/or Thermostability of PET Hydrolase by D186 Mutations.

PETase exhibits a high degradation activity for polyethylene terephthalate (PET) plastic under moderate temperatures. However, the effect of non-active site residues in the second shell of PETase on the catalytic performance remains unclear. Herein, we proposed a crystal structure- and sequence-based strategy to identify the key non-active site residue. D186 in the second shell of PETase was found to be capable of modulating the enzyme activity and stability. The most active PETaseD186N improved both the activity and thermostability with an increase in Tm by 8.89 °C. The PET degradation product concentrations were 1.86 and 3.69 times higher than those obtained with PETaseWT at 30 and 40 °C, respectively. The most stable PETaseD186V showed an increase in Tm of 12.91 °C over PETaseWT. Molecular dynamics (MD) simulations revealed that the D186 mutations could elevate the substrate binding free energy and change substrate binding mode, and/or rigidify the flexible Loop 10, and lock Loop 10 and Helix 6 by hydrogen bonding, leading to the enhanced activity and/or thermostability of PETase variants. This work unraveled the contribution of the key second-shell residue in PETase in influencing the enzyme activity and stability, which would benefit in the rational design of efficient and thermostable PETase.

New combined absorption/1H NMR method for qualitative and quantitative analysis of PET degradation products.

Poly(ethylene terephthalate) (PET) is a very valuable and beneficial material for industrial purposes, with various different applications. Due to the high annual production volume of over 50 million tons worldwide and the indiscriminate disposal by consumers, the polymers accumulate in the environment, causing negative effects on various ecosystems. Biodegradation via suitable enzymes represents a promising approach to combat the plastic waste issue so validated methods are required to measure the efficiency and efficacy of these enzymes. PETase and MHETase from Ideonella sakaiensis are suitable enzymes needed in combination to completely degrade PET into its environmentally friendly monomers. In this project, we compare and combine a previously described bulk absorbance measurement method with a newly established 1H NMR analysis method of the PET degradation products mono(2-hydroxyethyl) terephthalic acid, bis(2-hydroxyethyl) terephthalic acid and terephthalic acid. Both were optimized regarding different solvents, pH values and drying processes. The accuracy of the measurements can be confirmed with sensitivity limits of 2.5-5 µM for the absorption method and 5-10 µM for the 1H NMR analysis. The combination of the described methods therefore allows a quantitative analysis by using bulk absorption coupled with a qualitative analysis through 1H NMR. The methods established in our work can potentially contribute to the development of suitable recycling strategies of PET using recombinant enzymes.

Computational redesign of a hydrolase for nearly complete PET depolymerization at industrially relevant high-solids loading.

Biotechnological plastic recycling has emerged as a suitable option for addressing the pollution crisis. A major breakthrough in the biodegradation of poly(ethylene terephthalate) (PET) is achieved by using a LCC variant, which permits 90% conversion at an industrial level. Despite the achievements, its applications have been hampered by the remaining 10% of nonbiodegradable PET. Herein, we address current challenges by employing a computational strategy to engineer a hydrolase from the bacterium HR29. The redesigned variant, TurboPETase, outperforms other well-known PET hydrolases. Nearly complete depolymerization is accomplished in 8 h at a solids loading of 200 g kg-1. Kinetic and structural analysis suggest that the improved performance may be attributed to a more flexible PET-binding groove that facilitates the targeting of more specific attack sites. Collectively, our results constitute a significant advance in understanding and engineering of industrially applicable polyester hydrolases, and provide guidance for further efforts on other polymer types.

Recycling and high-value utilization of polyethylene terephthalate wastes: A review.

Polyethelene terephthalate (PET) is a well-known thermoplastic, and recycling PET waste is important for the natural environment and human health. This study provides a comprehensive overview of the recycling and reuse of PET waste through energy recovery and physical, chemical, and biological recycling. This article summarizes the recycling methods and the high-value products derived from PET waste, specifically detailing the research progress on regenerated PET prepared by the mechanical recycling of fiber/yarn, fabric, and composite materials, and introduces the application of PET nanofibers recycled by physical dissolution and electrospinning in fields such as filtration, adsorption, electronics, and antibacterial materials. This article explains the energy recovery of PET through thermal decomposition and comprehensively discusses various chemical recycling methods, including the reaction mechanisms, catalysts, conversion efficiencies, and reaction products, with a brief introduction to PET biodegradation using hydrolytic enzymes provided. The analysis and comparison of various recycling methods indicated that the mechanical recycling method yielded PET products with a wide range of applications in composite materials. Electrospinning is a highly promising recycling strategy for fabricating recycled PET nanofibers. Compared to other methods, physical recycling has advantages such as low cost, low energy consumption, high value, simple processing, and environmental friendliness, making it the preferred choice for the recycling and high-value utilization of waste PET.

Analysis of Poly(ethylene terephthalate) degradation kinetics of evolved IsPETase variants using a surface crowding model.

Poly(ethylene terephthalate) (PET) is a major plastic polymer utilized in the single-use and textile industries. The discovery of PET-degrading enzymes (PETases) has led to an increased interest in the biological recycling of PET in addition to mechanical recycling. IsPETase from Ideonella sakaiensis is a candidate catalyst, but little is understood about its structure-function relationships with regards to PET degradation. To understand the effects of mutations on IsPETase productivity, we develop a directed evolution assay to identify mutations beneficial to PET film degradation at 30 °C. IsPETase also displays enzyme concentration-dependent inhibition effects, and surface crowding has been proposed as a causal phenomenon. Based on total internal reflectance fluorescence microscopy and adsorption experiments, IsPETase is likely experiencing crowded conditions on PET films. Molecular dynamics simulations of IsPETase variants reveal a decrease in active site flexibility in free enzymes and reduced probability of productive active site formation in substrate-bound enzymes under crowding. Hence, we develop a surface crowding model to analyze the biochemical effects of three hit mutations (T116P, S238N, S290P) that enhanced ambient temperature activity and/or thermostability. We find that T116P decreases susceptibility to crowding, resulting in higher PET degradation product accumulation despite no change in intrinsic catalytic rate. In conclusion, we show that a macromolecular crowding-based biochemical model can be used to analyze the effects of mutations on properties of PETases and that crowding behavior is a major property to be targeted for enzyme engineering for improved PET degradation.

Applications of waste polyethylene terephthalate (PET) based nanostructured materials: A review.

While polyethylene terephthalate (PET) has enjoyed widespread use, a large volume of plastic waste has also been produced as a result, which is detrimental to the environment. Traditional treatment of plastic waste, such as landfilling and incinerating waste, causes environmental pollution and poses risks to public health. Recycling PET waste into useful chemicals or upcycling the waste into high value-added materials can be remedies. This review first provides a brief introduction of the synthesis, structure, properties, and applications of virgin PET. Then the conversion process of waste PET into high value-added materials for different applications are introduced. The conversion mechanisms (including degradation, recycling and upcycling) are detailed. The advanced applications of these upgraded materials in energy storage devices (supercapacitors, lithium-ion batteries, and microbial fuel cells), and for water treatment (to remove dyes, heavy metals, and antibiotics), environmental remediation (for air filtration, CO2 adsorption, and oil removal) and catalysis (to produce H2, photoreduce CO2, and remove toxic chemicals) are discussed at length. In general, this review details the exploration of advanced technologies for the transformation of waste PET into nanostructured materials for various applications, and provides insights into the role of high value-added waste products in sustainability and economic development.