Approaches to the source evaluation of chlorinated polycyclic aromatic hydrocarbons in fine particles.

Chlorinated polycyclic aromatic hydrocarbons (ClPAHs) have been recognized as novel hazardous pollutants; however, the dominant sources remain unclear. This study investigates the occurrences of ClPAHs in five stages of size-segregated particles collected from an urban site and evaluates the sources and factors affecting the concentrations using organic and inorganic source tracers. ClPAHs are the most frequently detected in the finest particle fraction (less than 1.1 µm; PM1.1), similar to polycyclic aromatic hydrocarbons (PAHs), hopanes, and levoglucosan (LEV). The concentrations of total ClPAHs in PM1.1 shows a significant correlation (p < 0.05) with those of total PAHs and specific hopanes but not to LEV and biogenic fatty acids; this suggests that ClPAHs dominantly originate from industrial activities and vehicular emissions. Heatmap analysis, including source tracers, is used to categorize the possible sources of ClPAHs into three types: ClPAH-specific sources, local industrial activities and vehicular emissions, and remote industrial activities. Furthermore, correlation network analysis is used to clarify the relationships between the pollutants.

Size Distribution of Chlorinated Polycyclic Aromatic Hydrocarbons in Atmospheric Particles.

The particle size distribution of chlorinated polycyclic aromatic hydrocarbons (ClPAHs) in particulate matter (PM) in Japan is examined for the first time. PM was collected using a PM0.1 air sampler with a six-stage filter. PM was collected in October 2014 and January 2015 to observe potential seasonal variation in the atmospheric behavior and size of PM, including polycyclic aromatic hydrocarbons (PAHs) and ClPAHs. We found that the concentration of PAHs and ClPAHs between 0.5-1.0 µm and 1.0-2.5 µm markedly increase in January (i.e., the winter season). Among the ClPAHs, 1-ClPyrene and 6-ClBenzo[a]Pyrene were the most commonly occurring compounds; further, approximately 15% of ClPAHs were in the nanoparticle phase (<0.1 µm). The relatively high presence of nanoparticles is a potential human health concern because these particles can easily be deposited in the lung periphery. Lastly, we evaluated the aryl hydrocarbon receptor (AhR) ligand activity of PM extracts in each size fraction. The result indicates that PM < 2.5 µm has the strong AhR ligand activity.

Spatio-temporal distribution, source, and genotoxic potential of polycyclic aromatic hydrocarbons in estuarine and riverine sediments from southern India.

In order to categorize the distribution, source, and effects of polycyclic aromatic hydrocarbons (PAHs) in aquatic systems of southern India, chemical and toxicological analyses were performed on surface and core sediments, collected from Adyar river, Cooum river, Ennore estuary, and Pulicat lake near Chennai city. The total PAH concentration in surface sediment ranged from 13 to 31,425ng/g with a mean value of 4320ng/g; the concentration was markedly higher in Cooum river compared to that at other sites. The historical PAH dissemination in core samples in the Cooum river, Ennore estuary, and Pulicat lake ranged from 30 to 31,425ng/g, from 8.6 to 910ng/g, and from 62 to 546ng/g, respectively. Surface sediments were predominantly contaminated with low molecular weight (LMW) PAHs. Historical profiles suggest that PAH contamination in the area is now greater than it had been in the past. PAH accumulation in Pulicat lake was distinct from that at other locations where high molecular weight (HMW) PAHs were predominant. DNA damage in HepG2 cells treated with sediment extracts from different locations showed a good correlation with their respective total PAH levels. Statistical analysis revealed that 3-ring and 4-ring PAHs may synergistically contribute to the genotoxic potency compared to others in sediments. The study also showed that a majority of PAHs in the study area indicated a petrogenic origin. Based on the enrichment and toxicological assessment of PAHs in sediments, Cooum river was shown to suffer the highest biological impairment among the studied water bodies.

Photochlorination of Polycyclic Aromatic Hydrocarbons in Acidic Brine Solution.

The potential for the formation of chlorinated polycyclic aromatic hydrocarbons via photochlorination of PAHs has been investigated in milli-Q water/synthetic water containing NaCl and PAHs with either UV or visible light. The photochlorination of pyrene occurred under acidic conditions in the presence of both UV and visible light, resulting in 1-chloropyrene as the main product. Benzo[a]pyrene yielded 6-chlorobenzo[a]pyrene following visible light irradiation; however the reaction was dependent upon solution pH. The photochlorination of PAHs was proposed to proceed via a consecutive reaction model. The rate constants associated with the photochlorination and photodecay processes were determined with the observed and theoretical values displaying similar trends, whereas the observed values were approximately 50-1000 times lower than the theoretical values. The lower observed values could be due to undergo photodecay rather than photochlorination of PAHs. Therefore, as photochlorination of PAHs appears to be significantly affected by solution pH, this information may allow for minimizing the impact on the environment.

Identification and characterization of oxidative metabolites of 1-chloropyrene.

Polycyclic aromatic hydrocarbons (PAHs) and chlorinated PAHs (ClPAHs) are ubiquitous contaminants that bind to the aryl hydrocarbon receptor (AhR) and exhibit mutagenic potential. It is difficult to monitor human exposure levels to ClPAHs because the exposure routes are complicated, and environmental concentrations are not always correlated with the levels of PAHs. Urinary PAH metabolites are useful biomarkers for evaluating PAH exposure, and ClPAH metabolites may therefore contribute to the estimation of ClPAH exposure. One of the most abundant ClPAHs present in the environment is 1-chloropyrene (ClPyr), and urinary ClPyr metabolites have the potential to be good biomarkers to evaluate the level of exposure to ClPAHs. Since the metabolic pathways involving ClPAHs are still undetermined, we investigated the effect of human cytochrome P450 enzymes on ClPyr and identified three oxidative metabolites by liquid chromatography-tandem mass spectrometry and nuclear magnetic resonance. We found that ClPyr was metabolized most efficiently by the P450 1A1 enzyme, followed by the 1B1 and 1A2 enzymes. Similar to ClPyr, these metabolites were shown to have agonist activity for the human AhR. We detected these metabolites when ClPyr reacted with a pooled human liver S9 fraction as well as in human urine samples. These results suggest that the metabolites may be used as biomarkers to evaluate the extent of exposure to ClPAHs.

Slowing single-stranded DNA translocation through a solid-state nanopore by decreasing the nanopore diameter.

To slow the translocation of single-stranded DNA (ssDNA) through a solid-state nanopore, a nanopore was narrowed, and the effect of the narrowing on the DNA translocation speed was investigated. In order to accurately measure the speed, long (5.3 kb) ssDNA (namely, ss-poly(dA)) with uniform length (±0.4 kb) was synthesized. The diameters of nanopores fabricated by a transmission electron microscope were controlled by atomic-layer deposition. Reducing the nanopore diameter from 4.5 to 2.3 nm slowed down the translocation of ssDNA by more than 16 times (to 0.18 µs base(-1)) when 300 mV was applied across the nanopore. It is speculated that the interaction between the nanopore and the ssDNA dominates the translocation speed. Unexpectedly, the translocation speed of ssDNA through the 4.5 nm nanopore is more than two orders of magnitude higher than that of double-stranded DNA (dsDNA) through a nanopore of almost the same size. The cause of such a faster translocation of ssDNA can be explained by the weaker drag force inside the nanopore. Moreover, the measured translocation speeds of ssDNA and dsDNA agree well with those calculated by molecular-dynamics (MD) simulation. The MD simulation predicted that reducing the nanopore diameter to almost the same as that of ssDNA (i.e. 1.4 nm) decreases the translocation speed (to 1.4 µs base(-1)). Narrowing the nanopore is thus an effective approach for accomplishing nanopore DNA sequencing.

Novel synthesis of cellulose-based diblock copolymer of poly(hydroxyethyl methacrylate) by mechanochemical reaction.

The mechanical fracture of polymer produces polymeric free radical chain-ends, by which liner block copolymers have been synthesized. A diblock copolymer of microcrystalline cellulose (MCC) and poly 2-hydroxyethyl methacrylate (pHEMA) was produced by the mechanochemical polymerization under vacuum and room temperature. The fraction of pHEMA in MCC-block-pHEMA produced by the mechanochemical polymerization increased up to 21 mol% with increasing fracture time (~6 h). Then, the tacticities of HEMA sequences in MCC-block-pHEMA varied according to the reaction time. In the process of mechanochemical polymerization, cellulose could play the role of a radical polymerization initiator capable of controlling stereoregularity.

Hazardous implications of halogenated polycyclic aromatic hydrocarbons in feedstuff: Congener specificity and toxic levels in feed ingredients and feeds.

Studies have shown that halogenated polycyclic aromatic hydrocarbons (HPAHs), including chlorinated (ClPAHs) and brominated PAHs (BrPAHs), could be hazardous pollutants due to their pervasive occurrence in the environment. However, their accumulation properties and toxic potentials in animal feedstuffs remain unclear. This study investigated 75 congeners of parent PAHs, ClPAHs, and BrPAHs in animal-based feed ingredients and fish and swine feeds in Japan using a GC/Orbitrap MS system. The total parent PAHs ranged from below the method detection limit (

Airborne PM2.5/PM10-associated chlorinated polycyclic aromatic hydrocarbons and their parent compounds in a suburban area in Shanghai, China.

Chlorinated polycyclic aromatic hydrocarbons (ClPAHs) have been reported to be formed during incineration processes. Despite dioxin-like toxicities of ClPAHs, little is known on the occurrence of these chemicals in the environment. In this study, concentrations of 24-h airborne PM10 and PM2.5-associated ClPAHs and their corresponding parent PAHs were monitored from October 2011 to March 2012 in a suburban area in Shanghai, China. In addition, daytime and nighttime particle samples were collected for 7 days in April from the same sampling site. Twelve of twenty ClPAH congeners were found in PM10 and PM2.5 at concentrations ranging from 2.45 to 47.7 pg/m(3) with an average value of 12.3 pg/m(3) for PM10, and from 1.34 to 22.3 pg/m(3) with an average value of 9.06 pg/m(3) for PM2.5. Our results indicate that ClPAHs are ubiquitous in inhalable fine particles. The concentrations of ∑ClPAHs and specific congeners such as 9-ClPhe, 3-ClFlu, 1-ClPyr, 7-ClBaA, and 6-ClBaP in particles collected during nighttime were higher than those collected during daytime, which suggests not only diffusion of ClPAHs in air by atmospheric mixing but also photochemical degradation during daylight hours. Among the individual ClPAHs determined, 6-ClBaP, 1-ClPyr, and 9-ClPhe were the dominant compounds in PM10 and PM2.5. The percent composition of 6-ClBaP, 1-ClPyr, 7-ClBaA, and 3-ClFlu between PM10 and PM2.5 was similar. Significant positive correlations were found between concentrations of ClPAHs and their corresponding parent PAHs, particle mass, and total organic carbon (organic carbon plus elemental carbon), indicating that ClPAHs are sorbed onto carbonaceous matter of PM. Concentrations of parent PAHs predicted by multiple linear regression models with PM mass, total organic carbon, temperature, and relative humidity as variables reflected the measured concentrations with a strong coefficient of determination of 0.917 and 0.946 for PM10 and PM2.5, respectively. However, the models generated to predict ClPAH concentrations in PM did not yield satisfactory results, which suggested the differences in physical-chemical properties and formation processes between ClPAHs and their corresponding parent PAHs. 7-ClBaA and 6-ClBaP collectively accounted for the preponderance of the total dioxin-like TEQ concentrations of ClPAHs (TEQClPAH) in PM samples. Exposure to toxic compounds such as ClPAHs and PAHs present in PM2.5 can be related to adverse health outcomes in people.

Voyaging of halogenated polycyclic aromatic hydrocarbons, an emerging group of pollutants, on micro-mesoplastics in the marine environment.

The limited existing research on the accumulation of hazardous chlorinated and brominated polycyclic aromatic hydrocarbons (ClPAHs and BrPAHs) in micro-mesoplastics (mMPs) motivated this investigation. We collected mMPs from the coastal environments of Sri Lanka and Japan. Out of 75 target compounds analyzed, 61 were detected, with total parent PAH concentrations reaching 16,300 and 1770 ng/g plastic in Sri Lanka and Japan, respectively. The total parent PAH concentrations in mMPs from the southern Sri Lankan coastline were relatively higher than those from the eastern coastline. Phenanthrene and naphthalene were the dominant parent PAH congeners in most mMP samples. Chlorinated pyrenes and brominated naphthalene were predominant among halogenated PAHs. The estimated toxic equivalency quotient (TEQ) ranged from 0.67 to 1057 ng-TEQ/g plastic, with the highest levels observed in polystyrene (PS) particles from the southern Sri Lankan coast. Benzo[a]pyrene and dibenzo[a,h]anthracene exhibited elevated TEQ for parent PAHs, whereas dichloropyrene, and dibromopyrene represented the highest TEQs for ClPAHs and BrPAHs, respectively. The data evidenced that several HPAH congeners can increase the PAH-like toxicity (∼86%) in mMPs. This study provides insights into the accumulation of parent and halogenated PAHs in mMPs, highlighting their potential combined implications in marine and terrestrial ecosystems.

Inhalation cancer risk associated with exposure to complex polycyclic aromatic hydrocarbon mixtures in an electronic waste and urban area in South China.

Atmospheric particulate matter samples were collected from May 2010 to April 2011 in a rural e-waste area and in Guangzhou, South China, to estimate the lifetime inhalation cancer risk from exposure to parent polycyclic aromatic hydrocarbons (PAHs), high molecular weight PAHs (MW 302 PAHs), and halogenated PAHs (HPAHs). Seasonal variations in the PAH concentrations and profiles within and between the e-waste and urban areas indicated different PAH sources in the two areas. Benzo[b]fluoranthene, benzo[a]pyrene, dibenz[ah]anthracene, and dibenzo[al]pyrene made the most significant contribution to the inhalation cancer risk. MW 302 PAHs accounted for 18.0% of the total cancer risk in the e-waste area and 13.6% in the urban area, while HPAHs made a minor contribution (<0.1%) in both the areas. The number of lifetime excess lung cancers due to exposure to parent PAHs, MW 302 PAHs, and HPAHs ranged from 15.1 to 1198 per million people in the e-waste area and from 9.3 to 737 per million people in Guangzhou. PAH exposure accounted for 0.02 to 1.94% of the total lung cancer cases in Guangzhou. On average, the inhalation cancer risk in the e-waste area was 1.6 times higher than in the urban area. The e-waste dismantling activities in South China led to higher inhalation cancer risk due to PAH exposure than the urban area.

Mechanoanions produced by mechanical fracture of bacterial cellulose: ionic nature of glycosidic linkage and electrostatic charging.

Mechanoanions were produced by heterogeneous scission of the glycosidic linkages of the main chain of bacterial cellulose (BC); scission was induced by mechanical fracture of the BC in a vacuum in the dark at 77 K. The mechanoanions were detected using electron-spin-trapping methods with tetracyanoethylene. The yield of mechanoanions was positively correlated with the absolute value of the change in the Mulliken atomic charge, which was used as a descriptor of the ionic nature of the glycosidic linkage. Homogeneous scission of the glycosidic linkages induced by mechanical fracture generated mechanoradicals, the electron affinity of which was estimated on the basis of the energy of the lowest unoccupied molecular orbital for the model structure of the mechanoradical. It was concluded that the electrostatic charging of BC is caused by electron transfer from mechanoanions to mechanoradicals, which have high electron affinities. The electrostatic charge density of BC in a vacuum in the dark at 77 K was estimated to be 6.00 × 10(-1) C/g.

Occurrences and Potential Sources of Halogenated Polycyclic Aromatic Hydrocarbons Associated with PM2.5 in Mumbai, India.

Occurrences of chlorinated and brominated polycyclic aromatic hydrocarbons (ClPAHs and BrPAHs, respectively) in fine aerosol particulate matter <2.5 µm in diameter were investigated in urban and suburban sites in Mumbai, India; and the possible sources from association with indicators, such as hopanes, steranes, and trace elements are discussed. The mean concentrations of total ClPAHs and BrPAHs were 0.54 and 0.25 ng/m3 in the urban site and 0.16 and 0.02 ng/m3 in the suburban site during the campaign, respectively. The variations in total Cl-/BrPAH concentrations showed a similar trend between the urban and suburban sites, whereas the composition profiles varied in each air sample. The relationships between the concentrations among individual compounds in the urban site suggest that dominant sources of Cl-/BrPAHs could be common to PAHs but not in the suburban site. Principal component analysis using the data set of certain compounds showed that Cl-/BrPAH concentrations in urban and suburban sites are occasionally driven by specific sources of either coal combustion or traffic emissions. In contrast, most air samples during the campaign could be attributed to a mix of those sources. Environ Toxicol Chem 2022;41:312-320. © 2021 SETAC.

Application of gas chromatographic retention times to determine physicochemical properties of nitrated, oxygenated, and parent polycyclic aromatic hydrocarbons.

Nitrated and oxygenated polycyclic aromatic hydrocarbons (NPAHs and OPAHs) are receiving attention because of their high toxicity compared with parent PAHs. However, the experimental data of their physicochemical properties has been limited. This study proposed the gas chromatographic retention time (GC-RT) technique as an effective alternative one to determine octanol-air partition coefficients (KOA) and sub-cooled liquid vapor pressures (PL) for 11 NPAHs, 10 OPAHs, and 19 parent PAHs. The slopes and intercepts of the linear regressions between temperature versus KOA and PL were provided and can be used to estimate KOA and PL for the 40 targeted compounds at any temperature. The internal energies of phase transfer (ΔUOA) and enthalpies of vaporization (ΔHL) for all targeted compounds were also calculated using the GC-RT technique. High-molecular-weight compounds may release or absorb higher heat energy to transform between different phases. NPAHs and OPAHs had a non-ideal solution behavior with activity in octanol (γoct) in the range of 19-53 and 18-1,078, respectively, which is larger than the unity threshold. A comparison among four groups of PAH derivatives showed that a functional group (nitro-, oxygen-, chloro-, and bromo-) in PAH derivatives increased γoct for corresponding parent PAHs by tens (mono-group) to hundreds of times (di-group). This study suggests that the GC-RT method is applicable for indirectly measuring the physicochemical properties of various groups of organic compounds.

Presence of Halogenated Polycyclic Aromatic Hydrocarbons in Milk Powder and the Consequence to Human Health.

Recent reports of the presence of halogenated derivatives of polycyclic aromatic hydrocarbons (PAHs) in human foods of animal origin, such as chlorinated (ClPAHs) and brominated (BrPAHs) PAHs, suggest that their contamination in dairy products may also pose a human health risk. This study used GC/Orbitrap-MS to analyze 75 congeners of halogenated PAHs and parent PAHs in milk and creaming powder samples commonly found in grocery stores in Sri Lanka and Japan. Our investigation revealed a total of 31 halogenated PAHs (HPAHs) in the samples. The concentrations of total parent PAHs in the samples from Sri Lanka and Japan ranged from not detected (n.d.)−0.13 and <0.001−16 ng/g dry weight (d.w.). Total ClPAHs and BrPAHs in the samples ranged from 0.01−3.35 and 1.20−5.15 ng/g (d.w.) for Sri Lanka, and 0.04−2.54 and n.d.−2.03 ng/g d.w. for Japan, respectively. The ClPAHs were dominated by chlorinated-pyrene, -fluoranthene, and -benzo[a]pyrene congeners, whereas the BrPAHs were dominated by brominated-naphthalene and -pyrene congeners. The toxic assessment estimated based on the intake of toxic equivalency quotients (TEQs) for target compounds in milk powders revealed that HPAHs might contribute additively to the PAHs-associated health risk to humans, indicating that more research is needed.

Comparative Study on the Distribution of Essential, Non-Essential Toxic, and Other Elements across Trophic Levels in Various Edible Aquatic Organisms in Sri Lanka and Dietary Human Risk Assessment.

Thirty-six elements are categorized as essential but toxic in excess amount (EBTEs), non-essential toxic (NETs), and Other in 29 different edible aquatic species dwelling in offshore pelagic, and coastal and estuarine (CE) ecosystems were investigated in Sri Lanka. Elements were analyzed using an energy-dispersive X-ray fluorescence (EDXRF) spectrometer, and an NIC MA-3000 Mercury Analyzer. EBTEs showed a negative relationship, whereas NETs showed a positive relationship between the concentration (mg/kg wet weight) and trophic levels in both ecosystems. EBTEs showed trophic dilution, whereas NETs showed trophic magnification. Some elements in a few organisms exceeded the maximum allowable limit which is safe for human consumption. There was a positive relationship (R2 = 0.85) between the concentration of mercury and body weight of yellowfin tuna (YFT). For the widely consumed YFT, the calculated hazard index (HI) for the non-carcinogenic health and exposure daily intake of NETs for adults were 0.27 and 9.38 × 10-5 mg/kg bw/day, respectively. The estimated provisional tolerable weekly intake (PTWI) (µg/kg bw/w) was 0.47 for arsenic and 0.05 for antimony, cadmium, mercury, and lead. The HI and PTWI values were below the recommended limits; thus, consumption of YFT does not pose any health risk for Sri Lankan adults.

Comparison of polycyclic aromatic hydrocarbon pollution in Chinese and Japanese residential air.

Comparative studies on polycyclic aromatic hydrocarbon (PAH) pollution in residential air of Hangzhou (China) and Shizuoka (Japan) were conducted in summer (August, 2006) and winter (January, 2007). Total concentrations of 8 PAHs ranged from 7.1 to 320 ng/m3 and 0.15 to 35 ng/m3 in residential air of Hangzhou and Shizuoka, respectively. Air PAH concentrations in smoking houses were higher than that in nonsmoking houses. In nonsmoking houses, mothball emission and cooking practice were the emission sources of 2- and 3-ring PAHs in Hangzhou, respectively. The 2- and 3-ring PAHs were from use of insect repellent, kerosene heating and outdoor environment in nonsmoking houses in Shizuoka. The 5- and 6-ring PAHs in residential air were mainly from outdoor environment in both cities. Toxicity potencies of PAHs in residential air of Hangzhou were much higher than that in Shizuoka.

Halogenated polycyclic aromatic hydrocarbons in edible aquatic species of two Asian countries: Congener profiles, biomagnification, and human risk assessment.

Seventy-five contaminants including chlorinated/brominated/parent polycyclic aromatic hydrocarbons (Cl/Br/PAHs) were investigated in 29 edible aquatic species from the Indian Ocean near Sri Lanka and 10 species from the Pacific Ocean near Japan. Concentrations of total ClPAHs and BrPAHs in the samples were 2.6-57 and 0.30-9.5 ng/g-dry weight from the Indian Ocean, and 0.35-18 and 0.03-3.3 ng/g-dry weight from the Pacific Ocean, respectively. Comparing the profiles of Cl/BrPAHs among the samples, congeners of chlorinated and brominated pyrene were predominant components and enhanced the potential for biomagnification in the sample from the off-shore pelagic environment in the Indian Ocean. The incremental lifetime cancer risks estimated by intake of the targets in consuming aquatic organisms showed that approximately one-third of studied organisms exceeded the acceptable risk level for Sri Lankans.

The association between antimicrobials and the antimicrobial-resistant phenotypes and resistance genes of Escherichia coli isolated from hospital wastewaters and adjacent surface waters in Sri Lanka.

The presence of antimicrobials, antimicrobial-resistant bacteria (ARB), and the associated antimicrobial resistance genes (ARGs) in the environment is a global health concern. In this study, the concentrations of 25 antimicrobials, the resistance of Escherichia coli (E. coli) strains in response to the selection pressure imposed by 15 antimicrobials, and enrichment of 20 ARGs in E. coli isolated from hospital wastewaters and surface waters were investigated from 2016 to 2018. In hospital wastewaters, clarithromycin was detected at the highest concentration followed by sulfamethoxazole and sulfapyridine. Approximately 80% of the E. coli isolates were resistant, while 14% of the isolates exhibited intermediate resistance against the tested antimicrobial agents. Approximately 61% of the examined isolates were categorized as multidrug-resistant bacteria. The overall abundance of phenotypes that were resistant toward drugs was in the following order: ß-lactams, tetracycline, quinolones, sulfamethoxazole/trimethoprim, aminoglycosides, and chloramphenicol. The data showed that the E. coli isolates frequently harbored blaTEM, blaCTX-M, tetA, qnrS, and sul2. These results indicated that personal care products were significantly associated with the presence of several resistant phenotypes and resistance genes, implying their role in co-association with multidrug resistance. Statistical analysis also indicated a disparity specific to the site, treatment, and year in the data describing the prevalence of ARB and ARGs and their release into downstream waters. This study provides novel insights into the abundance of antimicrobial, ARB and ARGs in Sri Lanka, and could further offer invaluable information that can be integrated into global antimicrobial resistance databases.

Diblock copolymer of bacterial cellulose and poly(methyl methacrylate) initiated by chain-end-type radicals produced by mechanical scission of glycosidic linkages of bacterial cellulose.

Bacterial cellulose (BC) was mechanically fractured in vacuum at 77 K; this resulted in the scission of the ß-1,4 glycosidic linkages of BC. The chain-end-type radicals (mechanoradicals) generated from the scissions were assigned by electron spin resonance (ESR) spectral analyses. A diblock copolymer of BC and poly(methyl methacrylate) (BC-block-PMMA) was produced by the mechanical fracture of BC with MMA (methyl methacrylate) in vacuum at 77 K. Radical polymerization of MMA was initiated by the mechanoradicals located on the BC surface. The BC surface was fully covered with the PMMA chains of the BC-block-PMMA. Novel modification of the BC surface with the BC-block-PMMA was confirmed by spectral analyses of ESR, Fourier-transform infrared, (1)H NMR, and gel permeation chromatography.