Displaying publications 41 - 60 of 268 in total

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  1. Salmon C, Song L, Muir K, UKGPCS Collaborators, Pashayan N, Dunning AM, et al.
    Eur J Epidemiol, 2021 Sep;36(9):913-925.
    PMID: 34275018 DOI: 10.1007/s10654-021-00781-1
    While being in a committed relationship is associated with a better prostate cancer prognosis, little is known about how marital status relates to its incidence. Social support provided by marriage/relationship could promote a healthy lifestyle and an increased healthcare seeking behavior. We investigated the association between marital status and prostate cancer risk using data from the PRACTICAL Consortium. Pooled analyses were conducted combining 12 case-control studies based on histologically-confirmed incident prostate cancers and controls with information on marital status prior to diagnosis/interview. Marital status was categorized as married/partner, separated/divorced, single, or widowed. Tumours with Gleason scores ≥ 8 defined high-grade cancers, and low-grade otherwise. NCI-SEER's summary stages (local, regional, distant) indicated the extent of the cancer. Logistic regression was used to derive odds ratios (ORs) and 95% confidence intervals (CI) for the association between marital status and prostate cancer risk, adjusting for potential confounders. Overall, 14,760 cases and 12,019 controls contributed to analyses. Compared to men who were married/with a partner, widowed men had an OR of 1.19 (95% CI 1.03-1.35) of prostate cancer, with little difference between low- and high-grade tumours. Risk estimates among widowers were 1.14 (95% CI 0.97-1.34) for local, 1.53 (95% CI 1.22-1.92) for regional, and 1.56 (95% CI 1.05-2.32) for distant stage tumours. Single men had elevated risks of high-grade cancers. Our findings highlight elevated risks of incident prostate cancer among widowers, more often characterized by tumours that had spread beyond the prostate at the time of diagnosis. Social support interventions and closer medical follow-up in this sub-population are warranted.
  2. Saad M, Alip A, Lim J, Abdullah MM, Chong FLT, Chua CB, et al.
    BJU Int, 2019 09;124(3):373-382.
    PMID: 31077523 DOI: 10.1111/bju.14807
    OBJECTIVE: To examine the results of the Malaysian Advanced Prostate Cancer Consensus Conference (MyAPCCC) 2018, held for assessing the generalizability of consensus reached at the Advanced Prostate Cancer Consensus Conference (APCCC 2017) to Malaysia, a middle-income country.

    METHODS: Six key sections were chosen: (1) high-risk localized and locally advanced prostate cancer, (2) oligometastatic prostate cancer, (3) castration-naïve prostate cancer, (4) castrate resistant prostate cancer, (5) use of osteoclast-targeted therapy and (6) global access to prostate cancer drugs. There were 101 consensus questions, consisting of 91 questions from APCCC 2017 and 10 new questions from MyAPCCC 2018, selected and modified by the steering committee; of which, 23 questions were assessed in both ideal world and real-world settings. A panel of 22 experts, comprising of 11 urologists and 11 oncologists, voted on 101 predefined questions anonymously. Final voting results were compared with the APCCC 2017 outcomes.

    RESULTS: Most voting results from the MyAPCCC 2018 were consistent with the APCCC 2017 outcomes. No consensus was achieved for controversial topics with little level I evidence, such as management of oligometastatic disease. No consensus was reached on using high-cost drugs in castration-naïve or castration-resistant metastatic prostate cancer in real-world settings. All panellists recommended using generic drugs when available.

    CONCLUSIONS: The MyAPCCC 2018 voting results reflect the management of advanced prostate cancer in a middle-income country in a real-world setting. These results may serve as a guide for local clinical practices and highlight the financial challenges in modern healthcare.

  3. Nairismägi ML, Tan J, Lim JQ, Nagarajan S, Ng CC, Rajasegaran V, et al.
    Leukemia, 2016 06;30(6):1311-9.
    PMID: 26854024 DOI: 10.1038/leu.2016.13
    Epitheliotropic intestinal T-cell lymphoma (EITL, also known as type II enteropathy-associated T-cell lymphoma) is an aggressive intestinal disease with poor prognosis and its molecular alterations have not been comprehensively characterized. We aimed to identify actionable easy-to-screen alterations that would allow better diagnostics and/or treatment of this deadly disease. By performing whole-exome sequencing of four EITL tumor-normal pairs, followed by amplicon deep sequencing of 42 tumor samples, frequent alterations of the JAK-STAT and G-protein-coupled receptor (GPCR) signaling pathways were discovered in a large portion of samples. Specifically, STAT5B was mutated in a remarkable 63% of cases, JAK3 in 35% and GNAI2 in 24%, with the majority occurring at known activating hotspots in key functional domains. Moreover, STAT5B locus carried copy-neutral loss of heterozygosity resulting in the duplication of the mutant copy, suggesting the importance of mutant STAT5B dosage for the development of EITL. Dysregulation of the JAK-STAT and GPCR pathways was also supported by gene expression profiling and further verified in patient tumor samples. In vitro overexpression of GNAI2 mutants led to the upregulation of pERK1/2, a member of MEK-ERK pathway. Notably, inhibitors of both JAK-STAT and MEK-ERK pathways effectively reduced viability of patient-derived primary EITL cells, indicating potential therapeutic strategies for this neoplasm with no effective treatment currently available.
  4. Lim J, Razi ZRM, Law JX, Nawi AM, Idrus RBH, Chin TG, et al.
    Tissue Eng Regen Med, 2018 Feb;15(1):75-87.
    PMID: 30603536 DOI: 10.1007/s13770-017-0086-6
    Umbilical cord (UC) is a discarded product from the operating theatre and a ready source of mesenchymal stromal cells (MSCs). MSCs from UC express both embryonic and adult mesenchymal stem cell markers and are known to be hypoimmunogenic and non-tumorigenic and thus suitable for allogeneic cell transplantation. Our study aimed to determine the degree of immunotolerance and bone-forming capacity of osteodifferentiated human Wharton's jelly-derived mesenchymal stromal cells (hWJ-MSCs) from different segments of UC in an allogenic setting. UCs were obtained from healthy donors delivering a full-term infant by elective Caesarean section. hWJ-MSCs were isolated from 3 cm length segment from the maternal and foetal ends of UCs. Three-dimensional fibrin constructs were formed and implanted intramuscularly into immunocompetent mice. The mice were implanted with 1) fibrin construct with maternal hWJ-MSCs, 2) fibrin construct with foetal hWJ-MSCs, or 3) fibrin without cells; the control group received sham surgery. After 1 month, the lymphoid organs were analysed to determine the degree of immune rejection and bone constructs were analysed to determine the amount of bone formed. A pronounced immune reaction was noted in the fibrin group. The maternal segment constructs demonstrated greater osteogenesis than the foetal segment constructs. Both maternal and foetal segment constructs caused minimal immune reaction and thus appear to be safe for allogeneic bone transplant. The suppression of inflammation may be a result of increased anti-inflammatory cytokine production mediated by the hWJ-MSC. In summary, this study demonstrates the feasibility of using bone constructs derived from hWJ-MSCs in an allogenic setting.
  5. Lim J, Razi ZR, Law J, Nawi AM, Idrus RB, Ng MH
    Cytotherapy, 2016 12;18(12):1493-1502.
    PMID: 27727016 DOI: 10.1016/j.jcyt.2016.08.003
    BACKGROUND AIMS: Human Wharton's jelly-derived mesenchymal stromal cells (hWJMSCs) are possibly the most suitable allogeneic cell source for stromal cell therapy and tissue engineering applications because of their hypo-immunogenic and non-tumorigenic properties, easy availability and minimal ethical concerns. Furthermore, hWJMSCs possess unique properties of both adult mesenchymal stromal cells and embryonic stromal cells. The human umbilical cord (UC) is approximately 50-60 cm long and the existing studies in the literature have not provided information on which segment of the UC was studied. In this study, hWJMSCs derived from three anatomical segments of the UC are compared.

    METHODS: Three segments of the whole UC, each 3 cm in length, were identified anatomically as the maternal, middle and fetal segments. The hWJMSCs from the different segments were analyzed via trypan blue exclusion assay to determine the growth kinetics and cell viability, flow cytometry for immunophenotyping and immunofluorescence and reverse transcriptase polymerase chain reaction (RT-PCR) for expression of stromal cell transcriptional factors. Furthermore, the trilineage differentiation potential (osteogenic, adipogenic and chondrogenic) of these cells was also assessed.

    RESULTS: hWJMSCs isolated from the maternal and fetal segments displayed greater viability and possessed a significantly higher proliferation rate compared with cells from the middle segment. Immunophenotyping revealed that hWJMSCs derived from all three segments expressed the MSC markers CD105, CD73, CD90, CD44, CD13 and CD29, as well as HLA-ABC and HLA-DR, but were negative for hematopoietic markers CD14, CD34 and CD45. Analysis of the embryonic markers showed that all three segments expressed Nanog and Oct 3/4, but only the maternal and fetal segments expressed SSEA 4 and TRA-160. Cells from all three segments were able to differentiate into chondrogenic, osteogenic and adipogenic lineages with the middle segments showing much lower differentiation potential compared with the other two segments.

    CONCLUSIONS: hWJMSCs derived from the maternal and fetal segments of the UC are a good source of MSCs compared with cells from the middle segment because of their higher proliferation rate and viability. Fetal and maternal segments are the preferred cell source for bone regeneration.

  6. Wong CHM, Xu N, Lim J, Feng KK, Chan WKW, Chan MTY, et al.
    Prostate, 2023 Jun;83(8):801-808.
    PMID: 36938957 DOI: 10.1002/pros.24519
    BACKGROUND: Androgen deprivation therapy (ADT) use in prostate cancer (PCa) has seen a rising trend. We investigated the relationship between ADT and adverse changes in metabolic parameters in an Asian population.

    METHODS: This is an international prospective multicenter single-arm cohort yielded from the real-life experience of ADT in Asia (READT) registry. Consecutive ADT-naïve patients diagnosed of PCa and started on ADT were prospectively recruited from 2016 and analyzed. Baseline patient characteristics, PCa disease status, and metabolic parameters were documented. Patients were followed up at 6-month interval for up to 5 years. Metabolic parameters including body weight, lipid profiles, and glycemic profiles were recorded and analyzed.

    RESULTS: 589 patients were eligible for analysis. ADT was associated with adverse glycemic profiles, being notable at 6 months upon ADT initiation and persisted beyond 1 year. Comparing to baseline, fasting glucose level and hemoglobin A1c level increased by 4.8% (p 

  7. Kruszka P, Porras AR, de Souza DH, Moresco A, Huckstadt V, Gill AD, et al.
    Am J Med Genet A, 2018 05;176(5):1128-1136.
    PMID: 29681090 DOI: 10.1002/ajmg.a.38672
    Williams-Beuren syndrome (WBS) is a common microdeletion syndrome characterized by a 1.5Mb deletion in 7q11.23. The phenotype of WBS has been well described in populations of European descent with not as much attention given to other ethnicities. In this study, individuals with WBS from diverse populations were assessed clinically and by facial analysis technology. Clinical data and images from 137 individuals with WBS were found in 19 countries with an average age of 11 years and female gender of 45%. The most common clinical phenotype elements were periorbital fullness and intellectual disability which were present in greater than 90% of our cohort. Additionally, 75% or greater of all individuals with WBS had malar flattening, long philtrum, wide mouth, and small jaw. Using facial analysis technology, we compared 286 Asian, African, Caucasian, and Latin American individuals with WBS with 286 gender and age matched controls and found that the accuracy to discriminate between WBS and controls was 0.90 when the entire cohort was evaluated concurrently. The test accuracy of the facial recognition technology increased significantly when the cohort was analyzed by specific ethnic population (P-value 
  8. Al-Hatamleh MAI, Ahmad S, Boer JC, Lim J, Chen X, Plebanski M, et al.
    J Oncol, 2019;2019:6313242.
    PMID: 31239840 DOI: 10.1155/2019/6313242
    In the past decade, nanomedicine research has provided us with highly useful agents (nanoparticles) delivering therapeutic drugs to target cancer cells. The present review highlights nanomedicine applications for breast cancer immunotherapy. Recent studies have suggested that tumour necrosis factor (TNF) and its receptor 2 (TNFR2) expressed on breast cancer cells have important functional consequences. This cytokine/receptor interaction is also critical for promoting highly immune-suppressive phenotypes by regulatory T cells (Tregs). This review generally provides a background for nanoparticles as potential drug delivery agents for immunomodulators and further discusses in depth the potential of TNF antagonists delivery to modulate TNF-TNFR2 interactions and inhibit breast cancer progression.
  9. Ahmad S, Zamry AA, Tan HT, Wong KK, Lim J, Mohamud R
    Mol Immunol, 2017 11;91:123-133.
    PMID: 28898717 DOI: 10.1016/j.molimm.2017.09.001
    Gold nanoparticles (NPs) have been proposed as a highly potential tool in immunotherapies due to its advantageous properties including customizable size and shapes, surface functionality and biocompatibility. Dendritic cells (DCs), the sentinels of immune response, have been of interest to be manipulated by using gold NPs for targeted delivery of immunotherapeutic agent. Researches done especially in human DCs showed a variation of gold NPs effects on cellular uptake and internalization, DC maturation and subsequent T cells priming as well as cytotoxicity. In this review, we describe the synthesis and physiochemical properties of gold NPs as well as the importance of gold NPs in immunotherapies through their actions on human DCs.
  10. Ahmad S, Azid NA, Boer JC, Lim J, Chen X, Plebanski M, et al.
    Front Immunol, 2018;9:2572.
    PMID: 30473698 DOI: 10.3389/fimmu.2018.02572
    Tumor necrosis factor-alpha (TNF) is a pleiotropic cytokine, which is thought to play a major role in the pathogenesis of inflammatory diseases, including allergy. TNF is produced at the early stage of allergen sensitization, and then continues to promote the inflammation cascade in the effector phase of allergic reactions. Consequently, anti-TNF treatment has been proposed as a potential therapeutic option. However, recent studies reveal anti-intuitive effects of TNF in the activation and proliferative expansion of immunosuppressive Tregs, tolerogenic DCs and MDSCs. This immunosuppressive effect of TNF is mediated by TNFR2, which is preferentially expressed by immunosuppressive cells. These findings redefine the role of TNF in allergic reaction, and suggest that targeting TNF-TNFR2 interaction itself may represent a novel strategy in the treatment of allergy.
  11. Sullivan T, Thirthagiri E, Chong CE, Stauffer S, Reid S, Southon E, et al.
    Hum Mutat, 2021 Feb;42(2):200-212.
    PMID: 33314489 DOI: 10.1002/humu.24154
    The discovery of high-risk breast cancer susceptibility genes, such as Breast cancer associated gene 1 (BRCA1) and Breast cancer associated gene 2 (BRCA2) has led to accurate identification of individuals for risk management and targeted therapy. The rapid decline in sequencing costs has tremendously increased the number of individuals who are undergoing genetic testing world-wide. However, given the significant differences in population-specific variants, interpreting the results of these tests can be challenging especially for novel genetic variants in understudied populations. Here we report the characterization of novel variants in the Malaysian and Singaporean population that consist of different ethnic groups (Malays, Chinese, Indian, and other indigenous groups). We have evaluated the functional significance of 14 BRCA2 variants of uncertain clinical significance by using multiple in silico prediction tools and examined their frequency in a cohort of 7840 breast cancer cases and 7928 healthy controls. In addition, we have used a mouse embryonic stem cell (mESC)-based functional assay to assess the impact of these variants on BRCA2 function. We found these variants to be functionally indistinguishable from wild-type BRCA2. These variants could fully rescue the lethality of Brca2-null mESCs and exhibited no sensitivity to six different DNA damaging agents including a poly ADP ribose polymerase inhibitor. Our findings strongly suggest that all 14 evaluated variants are functionally neutral. Our findings should be valuable in risk assessment of individuals carrying these variants.
  12. Mat S, Jaafar MH, Razack AHA, Lim J, Ong TA, Khong SY, et al.
    Neurourol Urodyn, 2023 Mar;42(3):641-649.
    PMID: 36728321 DOI: 10.1002/nau.25136
    INTRODUCTION: The common assumption that urinary incontinence occurs in osteoarthritis (OA) due to poor mobility is supported by limited evidence. The influence of gender in such associations is also yet to be elucidated.

    OBJECTIVE: This study, therefore, identified any potential associations between knee OA symptoms and urinary incontinence and further explore sex differences in the associations.

    DESIGN: Cross-sectional study.

    SETTING: University Hospital.

    PARTICIPANTS: This was a cross-sectional study from a longitudinal research study comprising 1221 community-dwelling older persons (57% women), mean age (SD) 68.95 (7.49) years.

    MAIN OUTCOME MEASURE(S): Presence of urinary incontinence: mixed, stress and urge symptoms. Physical performance and C-reactive protein levels were also assessed.

    RESULTS: Two hundred and seventy-seven (22.83%) individuals reported the presence of urinary incontinence: mixed (41.5%), stress (30%), and urge (28.5%) symptoms. In an unadjusted analysis, stratified by gender, the association between knee pain and urinary incontinence was only present in women with mixed symptoms. After further adjustment of demographics differences and body mass index, the association between knee pain with any urinary incontinence and mixed symptoms remained significant with the odds ratios (95% confidence interval): 1.48 (1.02-2.15) and 1.73 (1.06-2.83), respectively. This relationship was attenuated after further adjustment for waist circumference and impaired lower limb mobility.

    CONCLUSION: Our study refutes previous assumptions that urinary incontinence in individuals with OA is attributed to impaired mobility alone, but introduces the role of abdominal obesity in this relationship, particularly in women. Future studies should assess the temporal relationship between body fat distribution and OA with urinary incontinence.

  13. Lim J, Malek R, Jr S, Toh CC, Sundram M, Woo SYY, et al.
    Cancer Med, 2021 11;10(22):8020-8028.
    PMID: 34626088 DOI: 10.1002/cam4.4319
    Prostate cancer is the third most common cancer in Malaysia with the lifetime risk of 1 in 117 men. Here, we initiated a longitudinal Malaysia Prostate Cancer (M-CaP) Study to investigate the clinical and tumour characteristics, treatment patterns as well as disease outcomes of multi-ethnic Asian men at real-world setting. The M-CaP database consisted of 1839 new patients with prostate cancer diagnosed between 2016 and 2018 from nine public urology referral centres across Malaysia. Basic demographic and clinical parameters, tumour characteristics, primary treatment, follow-up and vital status data were retrieved prospectively from the hospital-based patients' case notes or electronic medical records. Primary endpoints were overall survival (OS) and biochemical progression-free survival (bPFS). The median age at diagnosis of M-CaP patients was 70 years (interquartile range, IQR 65-75). Majority of patients were Chinese (831, 45.2%), followed by Malays (704, 38.3%), Indians (124, 6.7%) and other races (181, 9.8%). The median follow-up for all patients was 23.5 months (IQR 15.9-33.6). Although 58.1% presented with late-stage cancer, we observed ethnic and geographic disparities in late-stage prostate cancer diagnosis. Curative radiotherapy and primary androgen deprivation therapy were the most common treatment for stage III and stage IV diseases, respectively. The median OS and bPFS of stage IV patients were 40.1 months and 19.2 months (95% CI 17.6-20.8), respectively. Late stage at presentation remains a challenge in multi-ethnic Asian men. Early detection is imperative to improve treatment outcome and survival of patients with prostate cancer.
  14. Lim J, Yeap SP, Leow CH, Toh PY, Low SC
    J Colloid Interface Sci, 2014 May 1;421:170-7.
    PMID: 24594047 DOI: 10.1016/j.jcis.2014.01.044
    Magnetophoresis of iron oxide magnetic nanoparticle (IOMNP) under low magnetic field gradient (<100 T/m) is significantly enhanced by particle shape anisotropy. This unique feature of magnetophoresis is influenced by the particle concentration and applied magnetic field gradient. By comparing the nanosphere and nanorod magnetophoresis at different concentration, we revealed the ability for these two species of particles to achieve the same separation rate by adjusting the field gradient. Under cooperative magnetophoresis, the nanorods would first go through self- and magnetic field induced aggregation followed by the alignment of the particle clusters formed with magnetic field. Time scale associated to these two processes is investigated to understand the kinetic behavior of nanorod separation under low field gradient. Surface functionalization of nanoparticles can be employed as an effective strategy to vary the temporal evolution of these two aggregation processes which subsequently influence the magnetophoretic separation time and rate.
  15. Lim J, Yeap SP, Che HX, Low SC
    Nanoscale Res Lett, 2013;8(1):381.
    PMID: 24011350 DOI: 10.1186/1556-276X-8-381
    Here we provide a complete review on the use of dynamic light scattering (DLS) to study the size distribution and colloidal stability of magnetic nanoparticles (MNPs). The mathematical analysis involved in obtaining size information from the correlation function and the calculation of Z-average are introduced. Contributions from various variables, such as surface coating, size differences, and concentration of particles, are elaborated within the context of measurement data. Comparison with other sizing techniques, such as transmission electron microscopy and dark-field microscopy, revealed both the advantages and disadvantages of DLS in measuring the size of magnetic nanoparticles. The self-assembly process of MNP with anisotropic structure can also be monitored effectively by DLS.
  16. Lim J, Pang HN, Tay K, Chia SL, Yeo SJ, Lo NN
    Malays Orthop J, 2020 Nov;14(3):73-81.
    PMID: 33403065 DOI: 10.5704/MOJ.2011.012
    Introduction: This study aims to investigate whether patients undergoing two-stage revision total hip arthroplasty (THA) for prosthetic joint infection (PJI) and one-stage revision THA for aseptic reasons have similar clinical outcomes and patient satisfaction during their post-operative follow-up. We hypothesise that the two-stage revision THA for PJI is associated with poorer outcomes as compared to aseptic revision THA.

    Materials and Methods: We reviewed prospectively collected data in our tertiary hospital arthroplasty registry and identified patients who underwent revision THA between 2001 and 2014, with a minimum of two years follow-up. The study group (two-stage revision THA for PJI) consists of 23 patients and the control group (one-stage revision THA for aseptic reasons) consists of 231 patients. Patient demographics, Western Ontario and McMaster Universities Arthritis Index (WOMAC), Oxford Hip Score (OHS), Short Form-36 (SF-36) scores and patient reported satisfaction were evaluated. Student's t-test was used to compare continuous variables between the two groups. Statistical significance was defined as p <0.05.

    Results: The pre-operative demographics and clinical scores were relatively similar between the two groups of patients. At two years, patients who underwent revision THA for PJI reported a better WOMAC Pain Score and OHS as compared to aseptic revision THA. A similar proportion of patients were satisfied with their results of surgery in both groups (p=0.093).

    Conclusions: Although patients who underwent revision THA for PJI had poorer pre-operative functional scores (WOMAC function and SF-36 PF), at two years follow-up, these two groups of patients have comparable post-operative outcomes. Interestingly, patients who had revision THA for PJI reported a better clinical outcome in terms of OHS and WOMAC Pain score as compared to the aseptic group. We conclude that the revision THA for PJI is not inferior to aseptic revision THA in terms of patient satisfaction and clinical outcomes.

  17. Soh EB, Lim JM
    Aust N Z J Obstet Gynaecol, 1999 Aug;39(3):389-90.
    PMID: 10554965
    This is a rare case of antepartum haemorrhage arising from the nonpregnant uterus in a woman with uterine didelphys. The bleeding and subsequent passage of a decidual cast did not have any adverse effect on the ongoing pregnancy.
  18. Arumugam K, Lim JM
    Br J Obstet Gynaecol, 1997 Aug;104(8):948-50.
    PMID: 9255089
    This case-controlled study investigates whether the presence of menstrual characteristics, which may increase the exposure of the peritoneal cavity to retrograde menstruation, increases the risk of developing endometriosis. The menstrual characteristics considered were 1. age at menarche of less than 12 years, 2. duration of menstrual flow greater than five days and 3. menstrual cycle lengths of < 28 days. The frequency with which these menstrual characteristics occurred in 305 women with proven endometriosis was compared with their frequency in 305 age-matched women without endometriosis. Adjusting for the confounding factors of parity, age at first childbirth and social class, the only menstrual characteristic that was significantly associated with endometriosis was menstrual cycle lengths of less than 28 days (odds ratio 1.83; 95% confidence intervals 1.60-2.55). There was insufficient evidence to conclude that the presence of menstrual characteristics which may increase the exposure of the peritoneal cavity to retrograde menstruation, increase a women's risk of developing endometriosis. The association of short menstrual cycle lengths with endometriosis may have been consequential rather than causal.
  19. Toh PY, Ng BW, Ahmad AL, Chieh DC, Lim J
    Nanoscale, 2014 Nov 7;6(21):12838-48.
    PMID: 25227473 DOI: 10.1039/c4nr03121k
    Successful application of a magnetophoretic separation technique for harvesting biological cells often relies on the need to tag the cells with magnetic nanoparticles. This study investigates the underlying principle behind the attachment of iron oxide nanoparticles (IONPs) onto microalgal cells, Chlorella sp. and Nannochloropsis sp., in both freshwater and seawater, by taking into account the contributions of various colloidal forces involved. The complex interplay between van der Waals (vdW), electrostatic (ES) and Lewis acid-base interactions (AB) in dictating IONP attachment was studied under the framework of extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) analysis. Our results showed that ES interaction plays an important role in determining the net interaction between the Chlorella sp. cells and IONPs in freshwater, while the AB and vdW interactions play a more dominant role in dictating the net particle-to-cell interaction in high ionic strength media (≥100 mM NaCl), such as seawater. XDLVO predicted effective attachment between cells and surface functionalized IONPs (SF-IONPs) with an estimated secondary minimum of -3.12 kT in freshwater. This prediction is in accordance with the experimental observation in which 98.89% of cells can be magnetophoretically separated from freshwater with SF-IONPs. We have observed successful magnetophoretic separation of microalgal cells from freshwater and/or seawater for all the cases as long as XDLVO analysis predicts particle attachment. For both the conditions, no pH adjustment is required for particle-to-cell attachment.
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