Plasma Pretreatment Research Articles

Effect of Argon Glow Plasma Pretreatment of Pure Ta on Hf Coating Preparation

In order to enhance the bonding strength between coatings and substrates, argon glow plasma pretreatment with various times was conducted on tantalum substrates, followed by hafnium coating deposition. The coating, consisting of deposition and a diffusion layer with nanocrystalline grains of dimensions ranging from 10 to 20 nm, obtained on the substrate pretreated for 1 h, manifested the optimal structure, with a maximum thickness of approximately 14 μm and the best adhesion performance of approximately 9.5 N. The study found that the pretreatment led to grain refinement at a depth of approximately 150 nm and an increase in the crystal face spacing of substrate and high-energy defects. In addition, the crystal defects and lightly increased surface roughness enhanced the surface energy, while the Ta (200) and Ta (211) crystal faces, which had a lower combination energy and a more stable state with Hf atoms than the Ta (110) crystal face, were considerably increased on pretreated substrates with a decrease in the Ta (110) crystal face. Consequently, coating elements exhibited enhanced diffusion within the substrate, leading to the better formation of a gradient structure, which effectively improved the adhesion of coatings. Further, this study offers an efficacious approach to enhance coating adhesion and provides a deeper understanding of plasma pretreatment.

Intensified extraction of anthocyanins from Berberis vulgaris L. by pulsed electric field, vacuum-cold plasma, and enzymatic pretreatments: modeling and optimization

BackgroundBerberis vulgaris L. is a valuable source of natural antioxidants, polyphenols, and anthocyanins compounds. Advanced extraction methods can increase extraction efficiency. This study investigated the efficiency of pulsed electric field, vacuum-cold plasma, and enzymatic pretreatment for anthocyanins extraction of Berberis vulgaris L.ResultsTotal polyphenols (TP), total anthocyanin (TA), and physicochemical properties of Berberis vulgaris L. were investigated. The pulsed electric field at three levels of electric intensity (3000, 5000, and 7000 V/cm) and three pulse numbers (50, 75, and 100) were applied. 7000 V/cm with the pulse number of 100 was the best condition for anthocyanin extraction (amounts of anthocyanin and polyphenol extraction were 260.28 mg/L and 462.75 mg/L, respectively). The vacuum-cold plasma was carried out at the power of 60, 70, and 80 w at different times (1, 3, and 5 min). The optimum conditions for vacuum-cold plasma were 80 w for 5 min, and anthocyanin and polyphenol amounts were 256.32 mg/L and 433.71 mg/L, respectively. The optimal conditions of enzymatic pretreatment for the maximum yield were 1.5% enzyme concentration at 60 °C (the values of extracted anthocyanin and polyphenol were 279.64 mg/L and 484.93 mg/L, respectively).ConclusionsDifferent extractionpretreatments demonstrated that the enzymatic pretreatment resulted in the highest extraction of anthocyanins and polyphenols from Berberis vulgaris L. Therefore, pectinase can act as a potential assisted extraction for the extraction process.Graphical

Alternative Eco-friendly Treatment of Hollow Cellulosic Fiber-Based Hybrid Composites for Remarkable Reactive Dyeing

Egyptian Chorisia hollow fibers have been blended with cotton waste, polyester waste, and raw bamboo at various ratios and weft counts using open-end spinning. The blended fabrics of hybrid composites were subjected to atmospheric plasma, pectinase, and lipase enzyme treatments, as well as the substitution of all hazardous chemicals, as sustainable alternatives to traditional alkaline scouring. The impacts of the treatments on the hollow-based fabrics' hydrophilicity, surface morphology, and color performance have been discussed. Pretreatment is associated with considerable weight loss (~ 12%) and a wetting time of less than 5 s which represents adequate absorbency of the composite. The enzymatic treatment contributed to looser arrangement of the fibrils which indicates an effective elimination of lignin and hemicellulose. The crystalline sections were greatly influenced by enzymatic treatment, providing effective decrease of cellulose crystallinity by about 30–40% as revealed by X-ray diffraction (XRD) measurements. Compared to conventional scouring, bio-scouring discharges significantly less effluent. The treated composite using either enzyme or plasma pretreatment method produced about at least 300% higher color yield (K/S) and 100% enhanced dye fixation (% F) than the untreated fabric. The lipase pretreatment without subsequent to atmospheric plasma treatment could be enough to achieve the highest hydrophilicity and color performance level under the experimental conditions.

Comparing Non-Thermal Plasma and Cold Stratification: Which Pre-Sowing Treatment Benefits Wild Plant Emergence?

Meadow restoration and creation projects have faced a lack of local seed diversity due to the limited availability of seed sources. Non-thermal plasma technologies are being developed for agriculture and do not cause damage to heat-sensitive biological systems. This technology has shown the potential to improve agronomic seed quality by enhancing germination and promoting plant growth. However, there is almost no information about the effect of non-thermal plasma pretreatment on the seedlings' emergence of wild plant species. Therefore, this study aimed to evaluate the effect of non-thermal plasma on the emergence of 17 plant seeds originating from local meadows in Lithuania and compare it with the cold stratification pretreatment. The results obtained indicate that there were differences in emergence parameters among the species. However, NTP did not show statistically significant differences from the control. Non-thermal plasma improved the kinetic parameters of emergence for a few specific species' seeds, such as Anthyllis vulneraria and Prunella grandiflora, while the cold stratification pretreatment enhanced emergence for a broader range of plants. Significant differences were observed between non-thermal plasma and stratification pretreatment, as well as between the control and stratification groups. Both methods also had a negative impact.

Effects of Plasma Pre-treatment on Field Germination and Seedling Growth of Platycodon Grandiflorum

This article explored the effects of plasma pre-treatment on the germination of Platycodon grandiflorum seeds. By analysing the effects of plasma pre-treatment on the germination, seedling growth and development of P. grandiflorum seeds, the study explored the best technological parameters of plasma pre-treatment for P. grandiflorum production and application, and promoted the application of plasma technology in the seed pre- treatment of P. grandiflorum. Based on field experiments, this study verified that plasma pre-treatment can have positive biological effects on P. grandiflorum. The Boltzmann equation was used to fit the germination-time process curve and the logistic equation was used to fit the growth-time process curve. According to the fitted equations, the prediction of the germination stage and the true leaf stage of P. grandiflorum were realised. Plasma pre-technology can increase the field germination of P. grandiflorum seeds by 23.9%. Furthermore, the growth advantage of P. grandiflorum during the germination period is maintained through to the true leaf stage. Plasma pre-treatment significantly shortened the time for P. grandiflorum seedlings to reach the true leaf stage and promoted growth and development.

Seed Science and Technology. Volume 51 Issue 2 (2023)

Seed-enhancement treatments as a theme run through many of the papers in the second issue of volume 51 of Seed Science and Technology: the uses of priming are explored in two papers, one of which compares agents with the potential to improve chilling tolerance of tobacco seed during germination, and the other suggests Pseudomonas fluorescens and Bacillus amyloliquefaciens as forms of biocontrol against Bacterial Fruit Blotch when priming melon seeds. Dormancy-breaking is essential for many species, and two papers proffer suggestions that can be applied to seeds of cucumber (dry heat) and to kala zeera (chilling, phytohormones). A lesser- utilised seed enhancement, that of plasma pre-treatments, is explored in terms of promoting seedling growth and development when applied to seeds of a popular horticultural species, Platycodon grandiflorus. Cautionary notes when following approved seed testing methods are sounded in a finding that the impact of variety complicates the interpretation of results when using the radicle emergence test to evaluate seed quality of wheat, and in a report of the results of a capacity-building exercise, where the correlation between skill levels and successful propagation of Melia volkensii seeds was evident. Useful SSR markers for assessing genetic similarity and degree of purity of wheat cultivars grown in Romania are suggested, as too is an approach to using germination and/or viability data in order to allow seed banks to make data-informed management decisions that would ensure time and resources are effectively allocated. An invited review gives a thorough and comprehensive review of all matters relating to the determination and control of seed moisture, and includes discussions on water activity and working with seed that needs to be at high moisture contents. A book review of ”Plant Regeneration from Seeds: A Global Warming Perspective ”strikes a positive note, concluding that it will leave readers with ”a deep appreciation for the complex interplay of factors that influence plant regeneration and the potential consequences for ecosystems around the world ”.

Application of cold plasma pretreatment to improve the extraction efficiency of tanshinone compounds from Salvia subg. Perovskia root

Tanshinone, a secondary metabolite derived from the medicinal plant Salvia subg. Perovskia, possesses therapeutic properties and has the potential to serve as a viable alternative to synthetic antioxidants in food industry. The primary objective of this study was to enhance the extraction efficiency of tanshinone compounds from Salvia subg. Perovskia through the utilization of various extraction techniques, such as heat reflux, ultrasonic, and microwave-hydrodistillation (MH) applying dielectric barrier discharge cold plasma as a pretreatment. Firstly, the optimum conditions of cold plasma pretreatment, ultrasonic, and microwave methods were determined at 18 kV for 1.5 min, 600 W for 25 min, and 100 W for 60 min, respectively, based on the extracted tanshinone content. The SEM analysis revealed that CP pretreatment caused notable changes in the cell walls, characterized by perforation, cracking, and the presence of cavities. The HPLC analysis identified three major components of tanshinone, including OH-CRT, CRT, and TAH-IIA, while GC–MS spectrometry detected 13 different volatile components in the extracted solutions. In conclusion, the combination of CP pretreatment with MH emerged as the most suitable method for extracting tanshinone compounds from Salvia subg. Perovskia, owing to its effective extraction capabilities, time-saving attributes, and energy efficiency. Moreover, the kinetic of tanshinone extraction through different methods were investigated using the first-order and second-order models. The statistical analysis clearly revealed that the second-order model accurately describes the tanshinone extraction process.

Effect of cold atmospheric pressure plasma pretreatment on the drying kinetics, physicochemical properties and selected bioactive compounds of okra pods subjected to hot air impingement drying

This study aimed to evaluate the effect of cold atmospheric pressure plasma pretreatment (CP) on the drying kinetics, physicochemical properties, content of chlorophylls (alpha and beta), lycopene, phenolic compounds and antioxidant capacity of hot air impingement dried (HAID) okra pods. CP treatment significantly increased moisture diffusivity from 3.04 x 10−9 to 5.07 x 10−9 m2/s and decreased the HAID time by 38%, i.e., from 235 to 145 min. CP resulted in a reduction of alpha chlorophyll and lycopene contents, whereas the combination of CP and HAID allowed both chlorophylls to be preserved. The HPLC-MS/MS analysis revealed that CP-treated samples showed lower content of phenolic compounds, while combination of CP for 15 s and HAID provided excellent preservation of these compounds. The results show that the combination of the advanced CP treatment and HAID method was useful to obtain optimal results for both drying kinetics and the quality of okra pods.

Increased radiosensitivity of melanoma cells through cold plasma pretreatment mediated by ICG.

Radiation therapy (RT) is the primary treatment for many cancers, but its effectiveness is reduced due to radioresistance and side effects. The study aims to investigate an emerging treatment for cancer, cold atmospheric plasma (CAP), as a selectable treatment between cancerous and healthy cells and its role in the occurrence of photodynamic therapy (PDT) utilizing indocyanine green (ICG) as a photosensitizer. We examined whether the efficiency of radiotherapy could be improved by combining CAP with ICG. The PDT effect induced by cold plasma irradiation and the radiosensitivity of ICG were investigated on DFW and HFF cell lines. Then, for combined treatment, ICG was introduced to the cells and treated with radiotherapy, followed by cold plasma treatment simultaneously and 24-h intervals. MTT and colony assays were used to determine the survival of treated cells, and flow cytometry was used to identify apoptotic cells. Despite a decrease in the survival of melanoma cells in CAP, ICG did not affect RT. Comparing the ICG + CAP group with CAP, a significant reduction in cell survival was observed, confirming the photodynamic properties of plasma utilizing ICG. The treatment outcome depends on the duration of CAP. The results for healthy and cancer cells also confirmed the selectivity of plasma function. Moreover, cold plasma sensitized melanoma cells to radiotherapy, increasing treatment efficiency. Treatment of CAP with RT can be effective in treating melanoma. The inclusion of ICG results in plasma treatment enhancement. These findings help to select an optimal strategy for a combination of plasma and radiotherapy.

Enhancement of Haskap Vacuum Freeze-Drying Efficiency and Quality Attributes Using Cold Plasma Pretreatment

Enhancement of Haskap Vacuum Freeze-Drying Efficiency and Quality Attributes Using Cold Plasma Pretreatment

Cold Plasma Technology for Tomato Processing By-Product Valorization: The Case of Tomato Peeling and Peel Drying

The tomato processing industry is focused on product yield maximization, keeping energy costs and waste effluents to a minimum while maintaining high product quality. In our study, cold atmospheric plasma (CAP) pretreatment enhanced tomato processing to facilitate peelability, a specific peeling process, and enhance peel drying. Peeling force analysis determined that CAP pretreatment of whole tomatoes improved peelability under the conditions used. The specific peeling force after CAP treatment decreased by more than three times. It was observed that cold atmospheric plasma pretreatment reduced the duration of infrared drying of tomato peels by 18.2%. Along with that, a positive effect on the reduction of the specific energy consumption of peel drying was shown for CAP-pretreated tomato peels. The obtained data show that the technology of cold atmospheric plasma pretreatment, in particular, when processing whole tomatoes and tomato peels, has a promising application in industry, as it can significantly reduce the specific energy consumption for peeling and drying procedures.

Intervention mechanisms of cold plasma pretreatment on the quality, antioxidants and reactive oxygen metabolism of fresh wolfberries during storage

Fresh wolfberries, a nutritious “super fruit”, face limited marketing potential due to storage difficulties. This study aimed to enhance their storage stability using dielectric barrier discharge plasma (DBD) pretreatment and investigate the intervention mechanism. The results indicated that the optimal condition of DBD pretreatment for fresh wolfberries was 13.64 kV, 70 s and 2.7 kHz, which extended their shelf from 2 to 5 d at room temperature. This pretreatment reduced decay, weight loss, and firmness reduction by inactivating microorganisms and inhibiting respiration. Additionally, the decline of phenols, flavonoids, ascorbic acid, and antioxidant activity was inhibited, while maintaining high content of polysaccharides, titratable acid, and carotenoids. Interestingly, moderate DBD treatment produced reactive oxygen species (ROS) that triggered the defense response of wolfberries' ROS metabolism system and promoted the biosynthesis of flavonoids, thereby enhancing resistance to decay. The findings offer new insight into plasma effects on fruits and vegetables.

Improving Printability of Polytetrafluoroethylene (PTFE) with the Help of Plasma Pre-Treatment.

Polytetrafluoroethylene (PTFE) is a potential candidate for the fabrication of flexible electronics devices and electronics with applications in various extreme environments, mainly due to its outstanding chemical and physical properties. However, to date, the utilization of PTFE in printing trials has been limited due to the material's low surface tension and wettability, which do not ensure good adhesion of the printing ink at the level of the substrate. Within this paper, successful printing of PTFE is realized after pre-treating the surface of the substrate with the help of dielectric barrier discharge non-thermal plasma. The efficiency of the pre-treatment is demonstrated with respect to both silver- and carbon-based inks that are commercially available, and finally, the long-lasting pre-treatment effect is demonstrated for periods of time spanning from minutes to days. The experimental results are practically paving the way toward large-scale utilization of PTFE as substrate in fabricating printed electronics in harsh working environments. After 3 s of plasma treatment of the foil, the WCA decreased from approximately 103° to approximately 70°. The resolution of the printed lines of carbon ink was not time dependent and was unmodified, even if the printing was realized within 1 min from the time of applying the pre-treatment or 10 days later. The evaluation of the surface tension (σ) measured with Arcotest Ink Pink showed an increase in σ up to 40 < σ < 42 mN/m for treated Teflon foil and from σ < 30 mN/m corresponding to the untreated substrate. The difference in resolution was distinguishable when increasing the width of the printed lines from 500 μm to 750 μm, but when increasing the width from 750 μm to 1000 μm, the difference was minimal.

Fabrication of double nano-emulsions loaded with hyssop (Hyssopus officinalis L.) extract stabilized with soy protein isolate alone and combined with chia seed gum in controlling the oxidative stability of canola oil

The aim of this study was to encapsulate hyssop (Hyssopus officinalis L.) extract obtained through ultrasound-assisted cold plasma pretreatment extraction within a double emulsion stabilized by soy protein isolate alone (SPI) and combined with chia seed gum (CSG) in the external aqueous phase on the stabilization of canola oil. FTIR analysis verified that there were electrostatic interactions between CSG and SPI. The SPI/CSG-stabilized emulsion demonstrated lower viscosity, smaller droplets, higher ζ-potential, and encapsulation efficiency compared to the SPI-stabilized emulsion. Non-Newtonian, pseudoplastic behaviors were shown by emulsions. Also, according to the dynamic rheological parameters (G' and G''), the SPI/CSG-stabilized emulsion had elastic behavior with weak gel properties. The antioxidant activity of the encapsulated extract at 1500 ppm during the storage in canola oil was investigated and compared to unencapsulated extract and TBHQ. The results showed that oil containing encapsulated extract had lower oxidative alterations than the unencapsulated form.

In-situ construction of plasma-pretreated CNT networks endow the LPDS dual-layer coating with advanced thermal management and anti-static properties

Carbon nanotubes (CNTs) for temperature regulation have been proven to be promising for passive radiative heat dissipation. However, it remains a considerable challenge to assemble a CNTs layer in situ while simultaneously achieving horizontal electrical conductivity, vertical electrical insulation, and radiative heat dissipation. Herein, plasma pretreatment was employed to functionalize CNTs in an aqueous solution, thus improving their dispersion capability. Subsequently, a liquid-plasma-assisted particle deposition and sintering (LPDS) technology was proposed to prepare a dual-layer coating with an Al2O3-P2O5-SiO2-In2O3 glass system embedded with crystalline indium tin oxide (ITO) as the porous bottom layer and ITO-CNTs as the top layer on the aluminum alloy surface. The results show that plasma pretreatment significantly increases the deposition amount of ITO nanoparticles and functionalized CNTs on the coating surface, resulting in the transition from a single-layer composite coating to a dual-layer coating. The surface micro-/nano hierarchical structure favors strong absorptance/emittance, exhibiting a high infrared emittance of 0.94 (3-20 μm) and high solar absorptance of 0.92 (0.2-2.5 μm). Meanwhile, the surface balance temperature of the dual-layer coating is about 392 K, which is 146 K lower than that of aluminum alloy. Furthermore, the top conductive ITO-CNTs layer contributes to the low surface resistivity of 3.46×102 Ω, while the glass phase of the bottom layer ensures vertical electrical insulation with a volume resistance of 4.20×107 Ω. The process provides a new path for preparing thermal control coatings with anti-static function.

Engineering Interface Defects and Interdiffusion at the Degenerate Conductive In2O3/Al2O3 Interface for Stable Electrodes in a Saline Solution.

A low-temperature Al2O3 deposition process provides a simplified method to form a conductive two-dimensional electron gas (2DEG) at the metal oxide/Al2O3 heterointerface. However, the impact of key factors of the interface defects and cation interdiffusion on the interface is still not well understood. Furthermore, there is still a blank space in terms of applications that go beyond the understanding of the interface's electrical conductivity. In this work, we carried out a systematic experimental study by oxygen plasma pretreatment and thermal annealing post-treatment to study the impact of interface defects and cation interdiffusion at the In2O3/Al2O3 interface on the electrical conductance, respectively. Combining the trends in electrical conductance with the structural characteristics, we found that building a sharp interface with a high concentration of interface defects provides a reliable approach to producing such a conductive interface. After applying this conductive interface as electrodes for fabricating a field-effect transistor (FET) device, we found that this interface electrode exhibited ultrastability in phosphate-buffered saline (PBS), a commonly used biological saline solution. This study provides new insights into the formation of conductive 2DEGs at metal oxide/Al2O3 interfaces and lays the foundation for further applications as electrodes in bioelectronic devices.

Enhanced Adhesion of Copper Films on Fused Silica Glass Substrate by Plasma Pre-Treatment.

A non-thermal atmospheric jet plasma pre-treatment technique was introduced to help the growth of extremely sticky copper films on fused silica glass substrates. A tape test was utilized to assess the bonding quality between copper films and fused silica glass substrates. AFM was used to characterize the sample surface roughness and XPS for chemical bonding characterization. The Owens-Wendt method and a Theta Lite Optical Tensiometer were used to analyze the contact angle and surface energy. The results showed that the surface energy greatly increased from 34.6 ± 0.3 mJ·m-2 to 55.9 ± 0.4 mJ·m-2 after 25 s plasma pre-treatment due to the increasing Si-O and Si-N concentrations, which brought about the electrostatic force increasing at the copper/glass interface. After 25 s plasma pre-treatment, the average surface roughness (Sa) grew from 0.8 ± 0.1 nm to 2.4 ± 0.3 nm. With higher surface roughness, there were more spaces and vacancies for the copper atoms to make contact on the bonded surfaces and increase the mechanical bite force. The electrostatic force and the mechanical bite force on the interface helped to form an atomic diffusion connection layer and improved the interactions between the copper film and the glass substrate. The findings in the SEM supported the conclusions stated above. Therefore, the adhesion between copper films and fused silica glass substrates increased by about 20% by 25 s plasma pre-treatment compared with the untreated glass substrate.

Effects of Cold Plasma Pretreatment on the Synthesis of Polysaccharide from Pleurotus ostreatus.

Fungal polysaccharides have attracted wide attention because of their medical pharmaceutical and health care value. So far, many efforts have been made in strain improvement to produce polysaccharides on a large scale at low cost. Here, a novel cold plasma-induced strain improvement technology was employed to pretreat Pleurotus ostreatus CGMCC 5.374 by radio-frequency (RF) low-vacuum cold plasma (LVCP) for the purpose of obtaining a high-yield polysaccharide strain. The optimum pretreatment conditions including discharge power, treatment time, and working pressure were determined by single factor and orthogonal experiment in succession. Furthermore, transcriptome analysis was conducted to study the effects of RF-LVCP on cell metabolism and proliferation. Results showed that under the optimal condition of discharge power of 130 W, treatment time of 25s and working pressure of 140Pa, polysaccharide content in mycelium was increased by 3.16% after 6days in comparison to the original strain. Transcriptome analysis showed that RF-LVCP is helpful for specific gene transcription profiles, Gene Ontology (GO) and KEGG pathways, of which the differentially expressed genes (DEGs) were mainly involve with the up-regulation of polysaccharide transport, physiology, synthesis and metabolism, as well as the down-regulation of polysaccharide hydrolysis and macromolecular degradation.

Evolution of Cu-In Catalyst Nanoparticles under Hydrogen Plasma Treatment and Silicon Nanowire Growth Conditions.

We report silicon nanowire (SiNW) growth with a novel Cu-In bimetallic catalyst using a plasma-enhanced chemical vapor deposition (PECVD) method. We study the structure of the catalyst nanoparticles (NPs) throughout a two-step process that includes a hydrogen plasma pre-treatment at 200 °C and the SiNW growth itself in a hydrogen-silane plasma at 420 °C. We show that the H2-plasma induces a coalescence of the Cu-rich cores of as-deposited thermally evaporated NPs that does not occur when the same annealing is applied without plasma. The SiNW growth process at 420 °C induces a phase transformation of the catalyst cores to Cu7In3; while a hydrogen plasma treatment at 420 °C without silane can lead to the formation of the Cu11In9 phase. In situ transmission electron microscopy experiments show that the SiNWs synthesis with Cu-In bimetallic catalyst NPs follows an essentially vapor-solid-solid process. By adjusting the catalyst composition, we manage to obtain small-diameter SiNWs-below 10 nm-among which we observe the metastable hexagonal diamond phase of Si, which is predicted to have a direct bandgap.

Evaluation of tumor mutation burden (TMB) in tumor (tDNA) and plasma cell free DNA (cfDNA) in patients (pts) with recurrent/metastatic head and neck squamous cell carcinoma (R/M HNSCC) treated with a combination of cetuximab and nivolumab (C+N).

6053 Background: High TMB is associated with immune checkpoint inhibitor (ICI) response in many solid tumors. However, obtaining sufficient tumor specimens for testing in a routine clinical setting could be a challenge. We evaluated TMB from whole-exome sequencing (WES) of cfDNA as a surrogate for tDNA TMB in R/M HNSCC pts treated with C+N. Methods: Archived formalin fixed paraffin embedded tumors, serially collected plasma (pre-treatment, on-treatment, and time of disease progression/end of treatment), peripheral mononuclear blood cells, and clinical data were obtained from R/M HNSCC pts treated with C+N from a completed clinical trial (NCT03370276). Nucleic acids were extracted using AllPrep DNA/RNA Mini Kit (Qiagen). Libraries were constructed using KAPA HyperPrep Kit with Library Amplification (KK8504) and IDT’s duplex UMI adapters. Hybridization and capture were performed using IDT’s XGen hybridization kit. Whole exome sequencing was performed using Illumina NovaSeq S4 flowcells (paired 151bp runs). Data preprocessing including point mutation calling, filtering, CNV calling, and purity and ploidy estimation were performed using the Getz Lab CGA WES Characterization pipeline. TMB for each sample was calculated based on the number of mutations with cancer cell fraction &gt; 0.75 as determined by ABSOLUTE and normalized to the 35Mb targeted for exome capture. Results: A total of 88 tDNA, 226 cfDNA, and 30 normal DNA (nDNA) from 82 pts were sequenced. To date, sequencing data from 13 matched tDNA/cfDNA/nDNA samples and 34 matched cfDNA/nDNA samples with sufficient tumor purity were available for analyses. The median TMB was 2.4 mut/Mb (range 0.46-17.5) in tDNA and 1.8 mut/Mb (range 1.1-12.6) in cfDNA. There was a high correlation between tDNA/cfDNA pairs in TMB (r = 0.826, p = 1.5x10-16, Pearson correlation). The median TMBs in tDNA and cfDNA obtained at different time points or treatment course did not differ significantly in 22 patients with at least two cfDNA timepoints (p = 0.26 paired t-test of log-transformed TMB). There was no difference between responder (R) vs. non-responder (NR) in cfDNA TMBs (two-sample t-test p = 0.7 between 2 R and 12 NR) and tDNA TMBs (two-sample t-test p = 0.25 between 6 R and 21 NR). However, tDNA TMB was higher in R compared NR in a subset of pts who did not have prior treatment with ICI (two-sample t-test p = 0.05 between 5 R and 2 NR). Conclusions: TMB in tDNA and cfDNA is highly correlated and suggests the possible use as a surrogate marker for tTMB. High TMB in cfDNA derived from ICI-naïve patients appears to have a prognostic value. Further evaluation is warranted to determine the role of cfDNA TMB as a biomarker of ICI response.