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  1. Sahudin MA, Su'ait MS, Tan LL, Lee YH, Abd Karim NH
    Anal Bioanal Chem, 2019 Sep;411(24):6449-6461.
    PMID: 31392436 DOI: 10.1007/s00216-019-02025-4
    Biogenic amines have attracted interest among researchers because of their importance as biomarkers in determining the quality of food freshness in the food industry. A rapid and simple technique that is able to detect biogenic amines is needed. In this work, a new optical sensing material for one of the biogenic amines, histamine, based on a new zinc(II) salphen complex was developed. The binding of zinc(II) complexes without an electron-withdrawing group (complex 1) and with electron-withdrawing groups (F, complex 2; Cl, complex 3) to histamine resulted in enhancement of fluorescence. All complexes exhibited high affinity for histamine [binding constant of (7.14 ± 0.80) × 104, (3.33 ± 0.03) × 105, and (2.35 ± 0.14) × 105 M-1, respectively]. Complex 2 was chosen as the sensing material for further development of an optical sensor for biogenic amines in the following step since it displayed enhanced optical properties in comparison with complexes 1 and 3. The optical sensor for biogenic amines used silica microparticles as the immobilisation support and histamine as the analyte. The optical sensor had a limit of detection for histamine of 4.4 × 10-12 M, with a linear working range between 1.0 × 10-11 and 1.0 × 10-6 M (R2 = 0.9844). The sensor showed good reproducibility, with a low relative standard deviation (5.5 %). In addition, the sensor exhibited good selectivity towards histamine and cadaverine over other amines, such as 1,2-phenylenediamine, triethylamine, and trimethylamine. Recovery and real sample studies suggested that complex 2 could be a promising biogenic amine optical sensing material that can be applied in the food industry, especially in controlling the safety of food for it to remain fresh and healthy for consumption.
  2. Mohamad NS, Tan LL, Ali NIM, Mazlan NF, Sage EE, Hassan NI, et al.
    Environ Sci Pollut Res Int, 2023 Mar;30(11):28422-28445.
    PMID: 36680719 DOI: 10.1007/s11356-023-25257-5
    The current study aims to provide a roadmap for future research by analyzing the research structures and trends in scholarly publications related to the status of zinc in public health. Only journal articles published between 1978 and 2022 are included in the refined bibliographical outputs retrieved from the Web of Science (WoS) database. The first section announces findings based on WoS categories, such as discipline heterogeneity, times cited and publications over time, and citation reports. The second section then employs VoSViewer software for bibliometric analysis, which includes a thorough examination of co-authorship among researchers, organizations, and countries and a count of all bibliographic databases among documents. The final section discusses the research's weaknesses and strengths in zinc status, public health, and potential future directions; 7158 authors contributed to 1730 papers (including 339 with publications, more than three times). "Keen, C.L." is a researcher with the most publications and a better understanding of zinc status in public health. Meanwhile, the USA has been the epicenter of research on the status of zinc in public health due to the highest percentage of publications with the most citations and collaboration with the rest of the world, with the top institution being the University of California, Davis. Future research can be organized collaboratively based on hot topics from co-occurrence network mapping and bibliographic couplings to improve zinc status and protect public health.
  3. Lee WPC, Wong FH, Attenborough NK, Kong XY, Tan LL, Sumathi S, et al.
    J Environ Manage, 2017 Jul 15;197:63-69.
    PMID: 28324782 DOI: 10.1016/j.jenvman.2017.03.027
    In the present work, two-dimensional bismuth oxybromide (BiOBr) was synthesized and coupled with co-catalyst molybdenum disulphide (MoS2) via a simple hydrothermal process. The photoactivity of the resulting hybrid photocatalyst (MoS2/BiOBr) was evaluated under the irradiation of 15 W energy-saving light bulb at ambient condition using Reactive Black 5 (RB5) as model dye solution. The photo-degradation of RB5 by BiOBr loaded with 0.2 wt% MoS2 (MoBi-2) exhibited more than 1.4 and 5.0 folds of enhancement over pristine BiOBr and titanium dioxide (Degussa, P25), respectively. The increased photocatalytic performance was a result of an efficient migration of excited electrons from BiOBr to MoS2, prolonging the electron-hole pairs recombination rate. A possible charge transfer diagram of this hybrid composite photocatalyst, and the reaction mechanism for the photodegradation of RB5 were proposed.
  4. Vaani VV, Tang MM, Tan LL, Asmah J
    Med J Malaysia, 2018 06;73(3):125-130.
    PMID: 29962494 MyJurnal
    INTRODUCTION: Ultraviolet phototherapies are important treatment modalities for a wide range of dermatological conditions. We aim to describe the utilization of phototherapy in the Department of Dermatology Hospital Kuala Lumpur.

    METHODS: This is a 5-year retrospective audit on patients who underwent phototherapy between 2011 and 2015.

    RESULTS: There were 892 patients, M:F=1.08:1, aged from 4- 88 years, with a median age of 38.8 years who underwent phototherapy. Majority (58.9%) had skin phototype IV, followed by type III (37.7%) and type II (0.7%). There were 697(78.1%) who underwent NBUVB, 136 (15.2%) had topical PUVA, 22(2.5%) had oral PUVA, 12(1.4%) had UVA1 and 23(2.6%) had NBUVB with topical or oral PUVA/UVA1 at different time periods. The indications were psoriasis (46.6%), vitiligo (26.7%), atopic eczema (9.8%), pityriasis lichenoides chronica (5.3%), mycosis fungoides (3.9%), lichen planus (2.5%), nodular prurigo (2.2%), scleroderma (1.2%), alopecia areata (0.7%) and others. The median number of session received were 27 (range 1-252) for NBUVB, 30 (range 1-330) for topical PUVA, 30 (range 3-190) for oral PUVA and 24.5 (range 2-161) for UVA1. The acute adverse effects experienced by patients were erythema (18%), pruritus (16.3%), warmth (3.3%), blister formation (3.1%), cutaneous pain (2.4%), and xerosis (0.8%), skin swelling (0.7%) and phototoxicity (0.2%).

    CONCLUSION: Narrow-band UVB was the most frequently prescribed phototherapy modality in our center. The most common indication for phototherapy in our setting was psoriasis. Acute adverse events occurred in a third of patients, although these side effects were mild.

  5. Chua PY, Day AC, Lai KL, Hall N, Tan LL, Khan K, et al.
    Br J Ophthalmol, 2018 Apr;102(4):539-543.
    PMID: 28794074 DOI: 10.1136/bjophthalmol-2017-310725
    PURPOSE: To estimate the incidence, and describe the clinical features and short-term clinical outcomes of acute angle closure (AAC).

    METHODS: Patients with newly diagnosed AAC were identified prospectively over a 12-month period (November 2011 to October 2012) by active surveillance through the Scottish Ophthalmic Surveillance Unit reporting system. Data were collected at case identification and at 6 months follow-up.

    RESULTS: There were 114 cases (108 patients) reported, giving an annual incidence of 2.2 cases (95% CI 1.8 to 2.6) or 2 patients (95% CI 1.7 to 2.4) per 1 00 000 in the whole population in Scotland. Precipitating factors were identified in 40% of cases. Almost one in five cases was associated with topical dilating drops. Best-corrected visual acuity (BCVA) at presentation ranged from 6/6 to perception of light. The mean presenting intraocular pressure (IOP) was 52 mm Hg (SD 11). Almost 30% cases had a delayed presentation of 3 or more days. At 6 months follow-up, 75% had BCVA of 6/12 or better and 30% were found to have glaucoma at follow-up. Delayed presentation (≥3 days) was associated with higher rate of glaucoma at follow-up (22.6% vs 60.8%, p<0.001), worse VA (0.34 vs 0.74 LogMAR, p<0.0001) and need for more topical medication (0.52 vs 1.2, p=0.003) to control IOP.

    CONCLUSION: The incidence of AAC in Scotland is relatively low compared with the Far East countries, but in line with previous European data. Almost one in five cases were associated with pupil dilation for retinal examination.

  6. Kwan Z, Lai YN, Ch'ng CC, Tan AH, Tan LL, Robinson S, et al.
    Med J Malaysia, 2015 Apr;70(2):81-5.
    PMID: 26162382 MyJurnal
    BACKGROUND: An association of bullous pemphigoid with neurological disorders has been reported. The objectives of this study were to review the clinical characteristics of patients with bullous pemphigoid and compare the association between bullous pemphigoid and various neurological disorders and comorbidities.

    METHODS: This was a retrospective case-control study involving 43 patients with bullous pemphigoid and 43 age-, sex- and ethnicity-matched controls.

    RESULTS: There was a statistically significant association between bullous pemphigoid and neurological disorders [Odds Ratio (OR) = 3.5, 95% Confidence Interval (CI) 1.3 to 9.2, p=0.011 and adjusted OR=3.5, 95% CI 1.2-10.3, p=0.026], in particular for dementia (p=0.002). Although stroke was more common among patients with bullous pemphigoid, this association was not statistically significant with OR of 1.9 (95% CI 0.7 to 5.2) and adjusted OR of 2.1 (95% CI 0.6 to 7.2). Similarly both ischaemic stroke (OR 1.5, 95% CI 0.5 to 4.2) and haemorrhagic stroke (OR 1.5, 95% CI 0.2 to 9.7) were more common. Other neurological disorders more common among patients with bullous pemphigoid were Parkinson's disease and epilepsy. Dyslipidaemia was significantly less common among patients with bullous pemphigoid (OR 0.4, 95% CI 0.1 to 0.9, p=0.033).

    CONCLUSION: A combination of an inflammatory process, prothrombotic state and endothelial activation leads to an increased frequency of neurological disorders among patients with bullous pemphigoid. Thus, a holistic approach to patient care, including screening for dementia and control of comorbidities, should be practised as bullous pemphigoid affects more than just the skin.
  7. Faheem NAA, Kwan Z, Yong ASW, Ch'ng CC, Tan KK, Naicker M, et al.
    Malays J Pathol, 2019 Apr;41(1):47-49.
    PMID: 31025637
    Naevus sebaceus is a cutaneous hamartoma with the potential of developing into benign or malignant neoplasms. Syringocystadenoma papilliferum (SCAP) have been reported to originate from naevus sebaceus. SCAP is a rare, benign adnexal skin tumour of apocrine or eccrine type of differentiation which typically presents as a nodule or a plaque on the scalp or face. We report a case of syringocystadenoma papilliferum arising in an undiagnosed pre-existing naevus sebaceus in a 56-year-old female.
  8. Tan LL, Chai SP, Mohamed AR
    ChemSusChem, 2012 Oct;5(10):1868-82.
    PMID: 22987439 DOI: 10.1002/cssc.201200480
    Graphene is one of the most promising materials in the field of nanotechnology and has attracted a tremendous amount of research interest in recent years. Due to its large specific surface area, high thermal conductivity, and superior electron mobility, graphene is regarded as an extremely attractive component for the preparation of composite materials. At the same time, the use of photocatalysts, particularly TiO(2), has also been widely studied for their potential in addressing various energy and environmental-related issues. However, bare TiO(2) suffers from low efficiency and a narrow light-response range. Therefore, the combination of graphene and TiO(2) is currently one of the most active interdisciplinary research areas and demonstrations of photocatalytic enhancement are abundant. This Review presents and discusses the current development of graphene-based TiO(2) photocatalysts. The theoretical framework of the composite, the synthetic strategies for the preparation and modification of graphene-based TiO(2) photocatalysts, and applications of the composite are reviewed, with particular attention on the photodegradation of pollutants and photocatalytic water splitting for hydrogen generation.
  9. Phang SJ, Lee J, Wong VL, Tan LL, Chai SP
    PMID: 35088270 DOI: 10.1007/s11356-021-18253-0
    Dye wastewater has raised a prevalent environmental concern due to its ability to prevent the penetration of sunlight through water, thereby causing a disruption to the aquatic ecosystem. Carbon quantum dots (CQDs) are particularly sought after for their highly tailorable photoelectrochemical and optical properties. Simultaneously, graphitic carbon nitride (g-C3N4) has gained widespread attention due to its suitable band gap energy as well as excellent chemical and thermal stabilities. Herein, a novel boron-doped CQD (BCQD)-hybridized g-C3N4 homojunction (CN) nanocomposite was fabricated via a facile hydrothermal route. The optimal photocatalyst sample, 1-BCQD/CN (with a 1:3 mass ratio of boron to CQD) accomplished a Rhodamine B (RhB, 10 mg/L) degradation efficiency of 96.8% within 4 h under an 18 W LED light irradiation. The kinetic rate constant of 1.39 × 10-2 min-1 achieved by the optimum sample was found to be 3.6- and 2.8-folds higher than that of pristine CN and un-doped CQD/CN, respectively. The surface morphology, crystalline structure, chemical composition and optical properties of photocatalyst samples were characterized via TEM, FESEM-EDX, XRD, FTIR, UV-Vis DRS and FL spectrometer. Based on the scavenging tests, it was revealed that the photogenerated holes (h+), superoxide anions (∙O2-) and hydroxyl radicals (∙OH) were the primary reactive species responsible for the photodegradation process. Overall, the highly efficient 1-BCQD/CN composite with excellent photocatalytic activity could provide a cost-effective and robust means to address the increasing concerns over global environmental pollution.
  10. Kwan Z, Che Ismail RB, Wong SM, Tan LL, Robinson S, Lim KS
    Int J Dermatol, 2014 Oct;53(10):e477-9.
    PMID: 25209632 DOI: 10.1111/ijd.12579
  11. Kwan Z, Bong YB, Tan LL, Lim SX, Yong AS, Ch'ng CC, et al.
    Psychol Health Med, 2017 02;22(2):184-195.
    PMID: 27541601 DOI: 10.1080/13548506.2016.1220603
    Patients with psoriasis may have increased risk of psychological comorbidities. This cross-sectional study aimed at determining associations between sociocultural and socioeconomic factors with the Depression Anxiety Stress Scale (DASS) scores and the Dermatology Life Quality Index (DLQI) scores. Adult patients with psoriasis were recruited from a Dermatology outpatient clinic via convenience sampling. Interviews were conducted regarding socio-demographic factors and willing subjects were requested to complete the DASS and DLQI questionnaires. The Pearson χ2 test, Fisher's exact test and multivariate logistic regression were used for statistical analysis to determine independent predictors of depression, anxiety, stress and severe impairment of quality of life. Unadjusted analysis revealed that depression was associated with Indian ethnicity (p = .041) and severe impairment of quality of life was associated with Indian ethnicity (p = .032), higher education (p = .013), higher income (p = .042), and employment status (p = .014). Multivariate analysis revealed that Indian ethnicity was a predictor of depression (p = .024). For stress, tertiary level of education (p = .020) was an independent risk factor while a higher monthly income was a protective factor (p = .042). The ethnic Indians and Malays were significantly more likely than the ethnic Chinese to suffer reduced quality of life (p = .001 and p = .006 respectively) and subjects with tertiary education were more likely to have severe impairment of quality of life (p = .002). Our study was unique in determining sociocultural influences on psychological complications of psoriasis in a South East Asian population. This has provided invaluable insight into factors predictive of adverse effects of psoriasis on psychological distress and quality of life in our patient population. Future studies should devise interventions to specifically target at risk groups in the development of strategies to reduce morbidity associated with psoriasis.
    Study site: Dermatology clinic, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia
  12. Yong SS, Kwan Z, Ch'ng CC, Yong ASW, Tan LL, Han WH, et al.
    BMC Geriatr, 2020 06 24;20(1):223.
    PMID: 32580764 DOI: 10.1186/s12877-020-01610-y
    BACKGROUND: The ageing skin is more susceptible to pruritic dermatoses, which are associated with adverse psychosocial effects and reduced quality of life among older adults. This cross-sectional study aimed to identify the burden of pruritus and factors associated with its presence and severity among older adults recruited to the Malaysian Elders Longitudinal Research study.

    METHODS: Seven hundred seventy individuals aged 55 years (lower age limit) and above were interviewed as to whether they experienced pruritus during the preceding week and the locations involved if present. The association between generalised pruritus, sleep quality, and major systemic risk factors were explored.

    RESULTS: 5.97% of respondents reported generalised pruritus. Generalised pruritus was associated with poorer sleep quality, with Pittsburgh Sleep Quality Index score above 6. Mean haemoglobin level was lower in subjects with generalised pruritus (13.14 g/dL) but there was no significant difference in the frequency of generalised pruritus and severe generalized pruritus between subjects with clinically defined anaemia. Also, there were no significant associations between other major systemic risk factors and generalised pruritus in this population-based study. There was no association between generalised pruritus with depression, anxiety or stress.

    CONCLUSION: The negative effect of pruritus on sleep quality suggests a possible deleterious effect of pruritus on health and quality of life. Further prospective research on the longer-term effects of pruritus on health status is now warranted. (222 words).

  13. Chong WK, Ng BJ, Lee YJ, Tan LL, Putri LK, Low J, et al.
    Nat Commun, 2023 Nov 24;14(1):7676.
    PMID: 37996415 DOI: 10.1038/s41467-023-43331-x
    Engineering an efficient semiconductor to sustainably produce green hydrogen via solar-driven water splitting is one of the cutting-edge strategies for carbon-neutral energy ecosystem. Herein, a superhydrophilic green hollow ZnIn2S4 (gZIS) was fabricated to realize unassisted photocatalytic overall water splitting. The hollow hierarchical framework benefits exposure of intrinsically active facets and activates inert basal planes. The superhydrophilic nature of gZIS promotes intense surface water molecule interactions. The presence of vacancies within gZIS facilitates photon energy utilization and charge transfer. Systematic theoretical computations signify the defect-induced charge redistribution of gZIS enhancing water activation and reducing surface kinetic barriers. Ultimately, the gZIS could drive photocatalytic pure water splitting by retaining close-to-unity stability for a full daytime reaction with performance comparable to other complex sulfide-based materials. This work reports a self-activated, single-component cocatalyst-free gZIS with great exploration value, potentially providing a state-of-the-art design and innovative aperture for efficient solar-driven hydrogen production to achieve carbon-neutrality.
  14. Sahudin MA, Su'ait MS, Tan LL, Abd Karim NH
    PMID: 33281086 DOI: 10.1016/j.saa.2020.119129
    Histamine is one of the important biomarkers for food spoilage in the food sectors. In the present study, a rapid and simple analytical tool has been developed to detect histamine as an indirect strategy to monitor food freshness level. Optical histamine sensor with carboxyl-substituted Schiff base zinc(II) complex with hydroxypropoxy side chain deposited onto titanium dioxide nanoparticles was fabricated and was found to respond successfully to histamine. The Schiff base zinc(II) complex-histamine binding generated an enhancement of the fluorescent signal. Under the optimal reaction condition, the developed sensor can detect down to 2.53 × 10-10 M in the range of between 1.0 × 10-9 and 1.0 × 10-5 M (R2 = 0.9868). Selectivity performance of the sensor towards histamine over other amines was confirmed. The sensor also displayed good reproducibility performances with low relative standard deviation values (1.45%-4.95%). Shelf-life studies suggested that the developed sensor remains stable after 60 days in histamine detection. More importantly, the proposed sensor has been successfully applied to determine histamine in salmon fillet with good recoveries. This strategy has a promising potential in the food quality assurance sectors, especially in controlling the food safety for healthy consumption among consumers.
  15. Jeningsih, Tan LL, Ulianas A, Heng LY, Mazlan NF, Jamaluddin ND, et al.
    Sensors (Basel), 2020 Mar 25;20(7).
    PMID: 32218202 DOI: 10.3390/s20071820
    A DNA micro-optode for dengue virus detection was developed based on the sandwich hybridization strategy of DNAs on succinimide-functionalized poly(n-butyl acrylate) (poly(nBA-NAS)) microspheres. Gold nanoparticles (AuNPs) with an average diameter of ~20 nm were synthesized using a centrifugation-based method and adsorbed on the submicrometer-sized polyelectrolyte-coated poly(styrene-co-acrylic acid) (PSA) latex particles via an electrostatic method. The AuNP-latex spheres were attached to the thiolated reporter probe (rDNA) by Au-thiol binding to functionalize as an optical gold-latex-rDNA label. The one-step sandwich hybridization recognition involved a pair of a DNA probe, i.e., capture probe (pDNA), and AuNP-PSA reporter label that flanked the target DNA (complementary DNA (cDNA)). The concentration of dengue virus cDNA was optically transduced by immobilized AuNP-PSA-rDNA conjugates as the DNA micro-optode exhibited a violet hue upon the DNA sandwich hybridization reaction, which could be monitored by a fiber-optic reflectance spectrophotometer at 637 nm. The optical genosensor showed a linear reflectance response over a wide cDNA concentration range from 1.0 × 10-21 M to 1.0 × 10-12 M cDNA (R2 = 0.9807) with a limit of detection (LOD) of 1 × 10-29 M. The DNA biosensor was reusable for three consecutive applications after regeneration with mild sodium hydroxide. The sandwich-type optical biosensor was well validated with a molecular reverse transcription polymerase chain reaction (RT-PCR) technique for screening of dengue virus in clinical samples, e.g., serum, urine, and saliva from dengue virus-infected patients under informed consent.
  16. Taib M, Tan LL, Abd Karim NH, Ta GC, Heng LY, Khalid B
    Talanta, 2020 Jan 15;207:120321.
    PMID: 31594568 DOI: 10.1016/j.talanta.2019.120321
    An optical aptasensor-based sensing platform for rapid insulin detection was fabricated. Aminated porous silica microparticles (PSiMPs) were synthesized via a facile mini-emulsion method to provide large surface area for covalent immobilization of insulin-binding DNA aptamer (IGA3) by glutaraldehyde cross-linking protocol. A Nickel-salphen type complex with piperidine side chain [Ni(II)-SP] was synthesized with a simple one-pot reaction, and functionalized as an optical label due to strong π-π interaction between aromatic carbons of G-quadruplex DNA aptamer and planar aromatic groups of Ni(II)-SP to form the immobilized IGA3-Ni(II)-SP complex, i.e. the dye-labeled aptamer, thereby bringing yellow colouration to the immobilized G-quartet plane. Optical characterization of aptasensor towards insulin binding was carried out with a fiber optic reflectance spectrophotometer. The maximum reflectance intensity of the immobilized IGA3-Ni(II)-SP complex at 656 nm decreased upon binding with insulin as aptasensor changed to brownish orange colouration in the background. This allows optical detection of insulin as the colour change of aptasensor is dependent on the insulin concentration. The linear detection range of the aptasensor is obtained from 10 to 50 μIU mL-1 (R2 = 0.9757), which conformed to the normal fasting insulin levels in human with a limit of detection (LOD) at 3.71 μIU mL-1. The aptasensor showed fast response time of 40 min and long shelf life stability of >3 weeks. Insulin detection using healthy human serums with informed consent provided by participants suggests the DNA aptamer biosensor was in good agreement with ELISA standard method using BIOMATIK Human INS (Insulin) ELISA Kit.
  17. Tan LL, Ong WJ, Chai SP, Mohamed AR
    Nanoscale Res Lett, 2013;8(1):465.
    PMID: 24195721 DOI: 10.1186/1556-276X-8-465
    Photocatalytic reduction of carbon dioxide (CO2) into hydrocarbon fuels such as methane is an attractive strategy for simultaneously harvesting solar energy and capturing this major greenhouse gas. Incessant research interest has been devoted to preparing graphene-based semiconductor nanocomposites as photocatalysts for a variety of applications. In this work, reduced graphene oxide (rGO)-TiO2 hybrid nanocrystals were fabricated through a novel and simple solvothermal synthetic route. Anatase TiO2 particles with an average diameter of 12 nm were uniformly dispersed on the rGO sheet. Slow hydrolysis reaction was successfully attained through the use of ethylene glycol and acetic acid mixed solvents coupled with an additional cooling step. The prepared rGO-TiO2 nanocomposites exhibited superior photocatalytic activity (0.135 μmol gcat-1 h-1) in the reduction of CO2 over graphite oxide and pure anatase. The intimate contact between TiO2 and rGO was proposed to accelerate the transfer of photogenerated electrons on TiO2 to rGO, leading to an effective charge anti-recombination and thus enhancing the photocatalytic activity. Furthermore, our photocatalysts were found to be active even under the irradiation of low-power energy-saving light bulbs, which renders the entire process economically and practically feasible.
  18. Fung CM, Er CC, Tan LL, Mohamed AR, Chai SP
    Chem Rev, 2022 Feb 09;122(3):3879-3965.
    PMID: 34968051 DOI: 10.1021/acs.chemrev.1c00068
    Photocatalysis is a perennial solution that promises to resolve deep-rooted challenges related to environmental pollution and energy deficit through harvesting the inexhaustible and renewable solar energy. To date, a cornucopia of photocatalytic materials has been investigated with the research wave presently steered by the development of novel, affordable, and effective metal-free semiconductors with fascinating physicochemical and semiconducting characteristics. Coincidentally, the recently emerged red phosphorus (RP) semiconductor finds itself fitting perfectly into this category ascribed to its earth abundant, low-cost, and metal-free nature. More notably, the renowned red allotrope of the phosphorus family is spectacularly bestowed with strengthened optical absorption features, propitious electronic band configuration, and ease of functionalization and modification as well as high stability. Comprehensively detailing RP's roles and implications in photocatalysis, this review article will first include information on different RP allotropes and their chemical structures, followed by the meticulous scrutiny of their physicochemical and semiconducting properties such as electronic band structure, optical absorption features, and charge carrier dynamics. Besides that, state-of-the-art synthesis strategies for developing various RP allotropes and RP-based photocatalytic systems will also be outlined. In addition, modification or functionalization of RP with other semiconductors for promoting effective photocatalytic applications will be discussed to assess its versatility and feasibility as a high-performing photocatalytic system. Lastly, the challenges facing RP photocatalysts and future research directions will be included to propel the feasible development of RP-based systems with considerably augmented photocatalytic efficiency. This review article aspires to facilitate the rational development of multifunctional RP-based photocatalytic systems by widening the cognizance of rational engineering as well as to fine-tune the electronic, optical, and charge carrier properties of RP.
  19. Hassan RA, Heng LY, Ahmad A, Tan LL
    PLoS One, 2019;14(4):e0214580.
    PMID: 30990847 DOI: 10.1371/journal.pone.0214580
    A potentiometric whole cell biosensor based on immobilized marine bacterium, Pseudomonas carrageenovora producing κ-carrageenase and glycosulfatase enzymes for specific and direct determination of κ-carrageenan, is described. The bacterial cells were immobilized on the self-plasticized hydrogen ion (H+)-selective acrylic membrane electrode surface to form a catalytic layer. Hydrogen ionophore I was incorporated in the poly(n-butyl acrylate) [poly(nBA)] as a pH ionophore. Catalytic decomposition of κ-carrageenan by the bienzymatic cascade reaction produced neoagarobiose, an inorganic sulfate ion and a proton. The latter was detectable by H+ ion transducer for indirect potentiometric quantification of κ-carrageenan concentration. The use of a disposable screen-printed Ag/AgCl electrode (SPE) provided no cleaning requirement and enabled κ-carrageenan detection to be carried out conveniently without cross contamination in a complex food sample. The SPE-based microbial biosensor response was found to be reproducible with high reproducibility and relative standard deviation (RSD) at 2.6% (n = 3). The whole cell biosensor demonstrated a broad dynamic linear response range to κ-carrageenan from 0.2-100 ppm in 20 mM phosphate buffer saline (PBS) at pH 7.5 with a detection limit at 0.05 ppm and a Nernstian sensitivity of 58.78±0.87 mV/decade (R2 = 0.995). The biosensor showed excellent selectivity towards κ-carrageenan compared to other types of carrageenans tested e.g. ι-carrageenan and λ-carrageenan. No pretreatment to the food sample was necessary when the developed whole cell biosensor was employed for direct assay of κ-carrageenan in dairy product.
  20. Tan LL, Ahmed SA, Ng SK, Citartan M, Raabe CA, Rozhdestvensky TS, et al.
    Food Chem, 2020 Mar 30;309:125654.
    PMID: 31678669 DOI: 10.1016/j.foodchem.2019.125654
    A specialized DNA extraction method and a SYBR Green quantitative polymerase chain reaction (SyG-qPCR) assay were combined to generate a ready-to-use kit for rapid detection of porcine admixtures in processed meat products. Our qPCR assay utilized repetitive LINE-1 elements specific to the genome of Sus scrofa domesticus (pig) as a target and incorporated internal controls. We improved the genomic DNA extraction method, and reduced extraction times to the minimum. The method was validated for specificity, sensitivity (0.001% w/w) and robustness, and values were compared with those of a commercially available kit. We also tested our method using 121 processed food products and consistently detected amplification only in samples containing pork. Due to its efficiency and cost-effectiveness, our method represents a valuable new method for detecting food adulteration with pork that is superior to existing quality control approaches.
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