Geškovski, Nikola

Preferred name

Geškovski, Nikola

Official Name

Geškovski, Nikola

Alternative Name

Geskovski, Nikola

Geskovski, N

Geshkovski, Nikola

Geshkovski, N

Гешковски, Никола

Гешковски, Н

Geskovski N

Main Affiliation

ngeskovski@ff.ukim.edu.mk

ngeskovski@gmail.com

Scopus Author ID

35487367700

Researcher ID

P-8934-2014

Now showing 1 - 10 of 36

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FT-NIR models for predicting film quality parameters in titanium dioxide-free tablet coatings
(Elsevier BV, 2025-02-01)
Gorachinov, Filip
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Koviloska, Monika
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Tnokovska, Katerina
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Atanasova, Ana
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Antovska, Packa
This study leverages Fourier Transform Near-Infrared (FT-NIR) spectroscopy to monitor the coating process of pharmaceutical tablets using PVA-based TiO2-free films, with talc and iron oxides as opacifiers. By employing a combination of multivariate analytical techniques, the correlation between film coating progression and film thickness was evaluated. Assessment of coating thickness for different coating levels was performed by optical microscopy. Additionally, using colorimetric analysis by scanner method, the color progression for different coating levels was evaluated and expressed as the a* value from CIELAB color space. The coordinate value a* showed predictable changes with the progression of the coating process and film thickness values, indicating its utility as a robust reference method for quality control and process optimization. The predictive capability of the OPLS models, validated against measured film thickness and the a* value, demonstrated low prediction errors and confirmed the models' effectiveness in distinguishing coating levels and accurately predicting film coating progression. The OPLS model used knowledge-based peaks of interest, which were further confirmed by loading and coefficient plots. The study demonstrated that film thickness, as a destructive, and a* value from CIELAB color space, as a non-destructive reference method for coating progression could be used during a controlled pharmaceutical coating process for product quality assessment and pharmaceutical process endpoint determination.
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The importance of AKR1D1 enzyme in drug metabolism
(Macedonian Pharmaceutical Association, 2022-12-31)
Shutevska, Kristina
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Zhivikj, Zoran
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Dimkovski, Aleksandar
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Evaluation of weight loss supplements toxicity in rifampicin pretreated HepG2 cells
(Macedonian Pharmaceutical Association, 2023-09)
Zhivikj, Zoran
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Shutevska, Kristina
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Bajatovska, Ana Marija
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Community pharmacy practice in Montenegro in the period January-April 2020
(Macedonian pharmaceutical association, 2022)
Djurdjic, Beti
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Maric, Savo
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PCA based screening for melamine adulteration in supplements for sport nutrition using vibrational spectroscopy tools
(Macedonian Pharmaceutical Association, 2023-09)
Shutevska, Kristina
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Bajatovska, Ana Marija
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Zivikj, Zoran
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In vitro cytotoxicity evaluation of nanoliposomes intended for brain drug delivery
(2021-09-16)
Dushko Shalabalija
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Ljubica Mihailova
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Zimmer, Andreas
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Differentiation of Cannabis seeds employing digital morphological screening and infrared spectroscopy coupled with multivariate modeling
(Elsevier, 2024-05-01)
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Trajkovska, Ana
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Cultivation of Cannabis for medicinal purposes primarily relies on seed propagation with expected variations in yield, cannabinoid content, growth rate and seed material non-uniformity. This study aims to employ digital methods for morphological analysis and infrared spectroscopy, combining them with multivariate analysis to characterize and differentiate Cannabis seeds. Morphological traits of 100 seeds from both commercial Cannabis specimens and wild-growing local varieties were analyzed using the high-throughput phenotyping software in addition to their collected infrared spectra in the mid-IR region. Subsequently, a chemometrics approach by means of Principal Component Analysis (PCA), Hierarchical Cluster Analysis (HCA), and Partial Least Square-Discriminatory Analysis (PLS-DA) was applied. The statistical indicators of the PLS-DA model (R2X=0.99, R2Y=0.63, Q2=0.64) demonstrate strong predictive capabilities for the differentiation of Cannabis seed specimens based on morphological attributes. The score scatter plot clearly shows a distinct grouping pattern, primarily driven by seed size. Wild-type seeds predominantly cluster into group 1, characterized by smaller diameters, while commercial seeds cluster into group 2. By analysing spectral data, in contrast to the expected differentiation based on secondary metabolites (cannabinoids) in the seeds, differentiation was based on the macronutrient profile with characteristic bands at 3275 cm−1, 2921 cm−1, 2852 cm−1, 1743 cm−1, 1630 cm−1, 1532 cm−1, 1459 cm−1, 1239 cm−1, 1157 cm−1, 1094 cm−1, 1018 cm−1, identified as the most distinctive spectral features. The PCA model (R2X=0.88 and Q2=0.85) was composed of 5 principal components explaining 88% of the spectral variations. The loading plot of the PLS-DA model reveals the distinctive spectral features for both groups (lipid and carbohydrate bands - group 2 samples, protein and water content - group 1 samples). The developed models have the potential for application for rapid screening of quality parameters of Cannabis seeds and their differentiation.
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Radiosensitizing properties of dual-functionalized carbon nanostructures loaded with temozolomide
(Beilstein Institut, 2025-02-19)
Milenkovska, Radmila
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In the present study, temozolomide (TMZ), a drug used for the treatment of anaplastic astrocytoma and glioblastoma multiforme (GBM), was incorporated into multiwalled carbon nanotubes (MWCNTs) and a MWCNTs–graphene (MWCNTs-G) hybrid compound, covalently functionalized with polyethylene glycol (PEG) 6000 and folic acid (FA), with an aim to prepare nanocarriers with the potential to prolong the drug circulation time, cross the blood–brain–tumor barrier (BBTB), and provide targeted and controlled drug release in the brain tumor cells. Cytotoxicity and effects on cell membrane integrity of the blank and TMZ-loaded dual-functionalized carbon nanostructures (CNs) were evaluated in vitro on a GBM cell line (U87MG), as well as their radiosensitizing properties after exposure of the pre-treated GBM cells to gamma radiation with a standard clinical dose for patients with GBM. All prepared formulations underwent biopharmaceutical and physicochemical characterization, including the formulations exposed to irradiation under the same conditions. For physicochemical characterization of the formulations, different techniques were used by which successful functionalization of the CNs and TMZ loading were confirmed and visualized; no significant changes in the structure of the CNs and TMZ after irradiation were observed. With single and dual functionalization, formulations with relatively high TMZ loading efficiency and drug content were prepared. They exhibited homogeneous particle size distributions and mean particle sizes and surface charges suitable for crossing the BBTB and targeting brain cancer cells. A biphasic drug release profile was observed for all functionalized TMZ-loaded formulations in simulated in vivo conditions, with a sustained release pointing to the potential for controlled release of TMZ in brain tumor cells. The formulations of the hybrid CN MWCNTs-G compared to the corresponding MWCNTs were characterized by a similar or slightly higher TMZ content, larger particle size, similar surface charge, and slightly faster TMZ release, which can be attributed to the planar structure of graphene that promotes TMZ binding to the surface on a larger scale. For the irradiated CNs, lower values for particle size, more positive values for surface charge, and accelerated TMZ release were observed, which could be explained by changes in the physicochemical characteristics of the prepared formulations upon irradiation. Significant concentration-dependent toxicity was observed for blank dual-functionalized CNs, being higher for MWCNTs-G-PEG6000-FA compared to MWCNTs-PEG6000-FA at the same formulation concentrations. With incorporation of TMZ into the functionalized CNs, the cell viability additionally decreased, maintaining the trend for higher cytotoxicity of the hybrid CN. Additional decrease in the viability of cells was observed when GBM cells pre-treated with the corresponding CNs were exposed to irradiation, which could be ascribed to changes in size, surface charge, and release kinetics of TMZ and to irradiation-induced changes in the microenvironment and cell membranes that promote uptake of a larger volume of carriers in the GBM cells. The higher cytotoxicity observed in the hybrid carrier formulations could most likely be attributed to the length of the hybrid carrier and the higher proportion of planar surface, which promotes more intense contact with the cells and rupture of cell membranes. Overall, the findings demonstrate the radiosensitizing properties of not only TMZ but also of CNs and point to a clinical benefit from combined treatment with carbon nanocarriers of TMZ and radiotherapy in GBM.
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Lipid nano-carriers with herbal extracts for targeted brain delivery and treatment of CNS disorders
(Macedonian pharmaceutical association, 2022)
Shalabalija, Dushko
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Mihailova, Ljubica
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Rapid quantification models for assessing melamine adulteration in sport nutrition supplements via benchtop and portable NIRS instruments
(Elsevier, 2024-09-05)
Kristina Shutevska
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Ana Marija Bajatovska
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Zoran Zhivikj
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Marija Zafirova Gjorgievska
Sport nutrition supplements (SNS) are vulnerable to adulteration with melamine, artificially augmenting their protein content as determined by conventional assay methodologies. Vibrational spectroscopy techniques are suitable for the detection of adulteration because they allow rapid analysis, require minimal sample preparation, and can perform numerous analyses in a short time. The aim of this study was to develop rapid quantification models for the determination of melamine adulteration in a variety of SNS matrices using NIRS (near-infrared spectroscopy) in combination with multivariate data processing. Moreover, a comparison of benchtop and portable NIR instruments was carried out. Employing a stepwise approach involving OPLS-DA and PLS analysis, matrix discrimination and prediction ability were investigated. The benchtop instrument effectively discriminated among matrices (R2Y = 0.964, Q2 = 0.933), while the portable device, although showing a slightly altered pattern, maintained favorable discrimination capability (R2Y = 0.966, Q2 = 0.931). The quantitative PLS models for each SNS matrix exhibited comparable statistical indicators for both instruments with reasonable errors for melamine content estimation and prediction (RMSEE: 0.3-2.4 %, RMSEP: 0.98-2.99 %). Higher estimation and prediction errors were observed for protein-containing samples in both acquisition modes, probably due to the tendency of protein agglomeration and adhesion to different surfaces, which affects the homogeneity of the powder. Despite data loss due to the narrower spectral range and lower resolution of the portable instrument, all models were found to be suitable for predicting melamine content in sport nutrition supplements.

Geškovski, Nikola

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